Skip to main content
main-content

Über dieses Buch


This book (vol. 3) presents the proceedings of the IUPESM World Congress on Biomedical Engineering and Medical Physics, a triennially organized joint meeting of medical physicists, biomedical engineers and adjoining health care professionals. Besides the purely scientific and technological topics, the 2018 Congress will also focus on other aspects of professional involvement in health care, such as education and training, accreditation and certification, health technology assessment and patient safety. The IUPESM meeting is an important forum for medical physicists and biomedical engineers in medicine and healthcare learn and share knowledge, and discuss the latest research outcomes and technological advancements as well as new ideas in both medical physics and biomedical engineering field.

Inhaltsverzeichnis

Frontmatter

Micro- and Nanosystems, Active Implants, Biosensors

Frontmatter

Semiconductor Ethanol Sensor Inducted with Visible Light

Modern semiconductor sensors are based on an MOS (metal–oxide–semiconductor) structure and their further development is tending to combine them together with UV irradiation. In this paper, a system is presented that can pave the way towards gas analyzers that rely on visible spectrum light. The article presents a semiconductor gas sensor induced with safe optical irradiation delivered from the LED matrix to the semiconductor surface. Different irradiation wavelengths (440, 530, 600, 710 nm) under constant flux were used separately to find the condition for the best sensor response on gas sorption. An output signal was recorded in zero-level emission and in the presence of ethanol. Changes in sensor response and signal rise/relaxation time constant in the presence of saturated ethanol vapor were observed. Sensor response to the ethanol vapor was detected for each used irradiation wavelength and it is approximated by the non-linear falling regression curve with the highest sensor response at 440 nm (R = 104%). In addition, the different rise and relaxation time constant of the signal trace was detected depending on the irradiation wavelength. The time constant ratio is approximated by the non-linear rising regression curve with a maximum value at 710 nm for both signal rise (τ = 0.61) and relaxation (τ = 2.08) parts.

Yu. Dekhtyar, M. Komars, M. Sneiders

Study of the Influence of the Molecular Weight of the Polymer Used as a Coating on Magnetite Nanoparticles

Designing coated magnetic nanoparticles for nanomedicine applications, such as magnetic resonance imaging contrast enhancement, hyperthermia, and drug-delivery, has been in the focus of scientific interest for the last decade. Biocompatible polymers are used as nanoparticles coating for its physical and chemical properties that are very useful for biomedical applications. The aim of this contribution was to prepare the magnetite nanoparticles stabilized with poly (ethylene glycol) (PEG) and poly (ethylene glycol) methyl ether (mePEG) to elucidate the influence of the molecular weight on the corresponding amount of coating. The X-ray diffraction studies determined inverse spinel structure of magnetite nanoparticles, and field–emission scanning electron microscopy indicated the formation of quasi-spherical nanostructures with the final average particle size of 88–136 nm depending on the type of polymer coating. The bonding status of different polymers on the magnetite nanoparticles was confirmed by the Fourier transform infrared spectroscopy. According to the thermogravimetric analysis polymer amount in nanocomposites is related to molecular weight in the PEG-modified MNPs. The results of this study indicate the possibility of controlling the properties of theranostics nanomaterials, starting from the molecular weight of the polymer used as a coating.

Christian Chapa, Diana Lara, Perla García

Classification Algorithm Improvement for Physical Activity Recognition in Maritime Environments

Human activity recognition using wearable sensors and classification methods provides valuable information for the assessment of user’s physical activity levels and for the development of more precise energy expenditure models, which can be used to proactively prevent cardiovascular diseases and obesity. The aim of this study was to evaluate how maritime environment and sea waves affect the performance of modern physical activity recognition methods, which has not yet been investigated. Two similar test suits were conducted on land and on a small yacht where subjects performed various activities, which were grouped into five different activity types of static, transitions, walking, running and jumping. Average activity type classification sensitivity with a decision tree classifier trained using land-based signals from one tri-axial accelerometer placed on lower back and leave-one-subject-out cross-validation scheme was 0.95 ± 0.01 while classifying the activities performed on land, but decreased to 0.81 ± 0.17 while classifying the activities on sea. An additional component produced by sea waves with a frequency of 0.3–0.8 Hz and a peak-to-peak amplitude of 2 m/s2 was noted in sea-based signals. Additional filtration methods were developed with the aim to remove the effect of sea waves using the least amount of computational power in order to create a suitable solution for real-time activity classification. The results of this study can be used to develop more precise physical activity classification methods in maritime areas or other locations where background affects the accelerometer signals.

Ardo Allik, Kristjan Pilt, Deniss Karai, Ivo Fridolin, Mairo Leier, Gert Jervan

First Steps Towards an Implantable Electromyography (EMG) Sensor Powered and Controlled by Galvanic Coupling

In the past it has been proposed to use implanted electromyography (EMG) sensors for myoelectric control. In contrast to surface systems, these implanted sensors provide signals with low cross-talk. To achieve this, miniature implantable devices that acquire and transmit real-time EMG signals are necessary. We have recently in vivo demonstrated electronic implants for electrical stimulation which can be safely powered and independently addressed by means of galvanic coupling. Since these implants lack bulky components as coils and batteries, we anticipate it will be possible to accomplish very thin implants to be massively deployed in tissues. We have also shown that these devices can have bidirectional communication. The aim of this work is to demonstrate a circuit architecture for embedding EMG sensing capabilities in our galvanically powered implants. The circuit was simulated using intramuscular EMG signals obtained from an analytical infinite volume conductor model that used a similar implant configuration. The simulations showed that the proposed analog front-end is compatible with the galvanic powering scheme and does not affect the implant’s ability to perform electrical stimulation. The system has a bandwidth of 958 Hz, an amplification gain of 45 dB, and an output-referred noise of 160 µVrms. The proposed embedded EMG sensing capabilities will boost the use of these galvanically powered implants for diagnosis, and closed-loop control.

Laura Becerra-Fajardo, Antoni Ivorra

Powering Implants by Galvanic Coupling: A Validated Analytical Model Predicts Powers Above 1 mW in Injectable Implants

While galvanic coupling for intrabody communications has been proposed lately by different research groups, its use for powering active implantable medical devices remains almost non-existent. Here it is presented a simple analytical model able to estimate the attainable power by galvanic coupling based on the delivery of high frequency (>1 MHz) electric fields applied as short bursts. The results obtained with the analytical model, which is in vitro validated in the present study, indicate that time-averaged powers above 1 mW can be readily obtained in very thin (diameter < 1 mm) and short (length < 20 mm) elongated implants when fields which comply with safety standards (SAR < 10 W/kg) are present in the tissues where the implants are located. Remarkably, the model indicates that, for a given SAR, the attainable power is independent of the tissue conductivity and of the duration and repetition frequency of the bursts. This study reveals that galvanic coupling is a safe option to power very thin active implants, avoiding bulky components such as coils and batteries.

Marc Tudela-Pi, Laura Becerra-Fajardo, Antoni Ivorra

Microfluidic Diamond Biosensor Using NV Centre Charge State Detection

In this work we develop DNA sensors that are based on charge switching in colour centres in diamond. The presented method allows the combination of luminescence sensor and electrochemical sensor working on the principle of electrochemical impedance spectroscopy (EIS). The sensor employs specifically designed diamond structures grown by the means of chemical Vapour deposition (CVD). This diamond structure consists of highly boron doped diamond electrode on which an intrinsic diamond layer is deposited. This intrinsic layer is about 15 nm thick and it contains NV colour centres. The device is then embedded in polydimethylsiloxane (PDMS) microfluidic flow cell and covered by a transparent indium tin oxide (ITO) coated electrode. The switching of the NV centre charge state as a response, on diamond surface termination, is crucial tool for the sensitive charged molecules sensing. First we demonstrated high sensitivity of the near surface NV centres on a diamond biosensor surface charge termination. The measured data are supported by band bending modelling. Negative O- terminated surface results in a preferable NV centre charge state of NV0 or NV−, whereas positive H- terminated surface leads to mostly non-PL NV+ charge state. By this principle any charged molecule, such as polymer on DNA, can be detected by a customized surface functionalization. Functionality of the microfluidic diamond device is also verified by the EIS.

Marie Krečmarová, Thijs Vandenryt, Michal Gulka, Emilie Bourgeois, Ladislav Fekete, Pavel Hubík, Ronald Thoelen, Vincent Mortet, Miloš Nesládek

UWB Platform for Vital Signs Detection and Monitoring

In this paper a non-invasive method for vital signs detection and monitoring employing ultrawide bandwidth (UWB) technology is proposed. The idea behind the proposed approach is to use UWB technology to measure the variations in RF communication channel characteristics to detect vital signs. The feasibility of the proposed approach was experimentally tested with custom developed software and hardware platform, based on Decawave DW1000 M module. The platform was specifically designed and optimized to enable data acquisition of physical parameters with high sampling rate. The experiment consisted of placing UWB transmitter and receiver units in predetermined positions on the anterior and posterior thoracic wall where the transmitter generates an ultra-short UWB pulse with a minimum bandwidth of 500 MHz. From the channel impulse response (CIR) of the UWB channel measured at the UWB receiver the information about the heart muscle contraction is extracted. The heart muscle contraction detection algorithm exploits on the fact that the heart movements are periodic and therefore suitable for detection in frequency domain. The algorithm for feature extraction processes the sampled signal frequency spectrum, in order to estimate the heart rate. The obtained results showed the validity of the proposed approach and the performance of the proposed method was evaluated in comparison with commercial ECG device.

Ivana Čuljak, Hrvoje Mihaldinec, Zrinka Kovačić, Mario Cifrek, Hrvoje Džapo

Neuroengineering, Neural Systems

Frontmatter

A Novel Hybrid Swarm Algorithm for P300-Based BCI Channel Selection

Channel selection procedures are essential to reduce the curse of dimensionality in Brain-Computer Interface systems. However, these selection is not trivial, due to the fact that there are $$ 2^{{N_{c} }} $$ possible subsets for an N c channel cap. The aim of this study is to propose a novel multi-objective hybrid algorithm to simultaneously: (i) reduce the required number of channels and (ii) increase the accuracy of the system. The method, which integrates novel concepts based on dedicated searching and deterministic initialization, returns a set of pareto-optimal channel sets. Tested with 4 healthy subjects, the results show that the proposed algorithm is able to reach higher accuracies (97.00%) than the classic MOPSO (96.60%), the common 8-channel set (95.25%) and the full set of 16 channels (96.00%). Moreover, these accuracies have been obtained using less number of channels, making the proposed method suitable for its application in BCI systems.

Víctor Martínez-Cagigal, Eduardo Santamaría-Vázquez, Roberto Hornero

The Probablistic Random Forest Clinico-Statistical Regression Analysis of MER Signals with STN-DBS and Enhancement of UPDRS

In this study, we present classification and regression analysis to predict the UPDRS score and its enhancement after the microelectrode STN signal recording (MER) with DBS surgery (implantation of the microelectrode). We hypothesized that a data informed grouping of features extrapolated from MER signals of STN can envisage restore (by decreasing the tremor) and functioning the motor improvement in Parkinson’s disease (PD) patients. A random—forest is used to account for unbalanced datasets and multiple observations per PD subject, and showed that only five features of STN-MER signals are sufficient and account for prognosting UPDRS advancement. This finding suggests that STN signal characteristics are maximum correlated to the extent of improvement motor restoration and motor behavior observed in STN DBS.

Venkateshwarla Rama Raju

A Computer Simulation Test of Feedback Error Learning-Based FES Controller for Controlling Random and Cyclic Movements

Feedback control of movements by functional electrical stimulation (FES) can be useful for restoring motor function of paralyzed subjects. However, it has not been used practically. Some of possible reasons were considered to be in designing a feedback FES controller and its parameter determination, and nonlinear characteristics with large time delay in muscle response to electrical stimulation, which are different between subjects. This study focused on the hybrid controller that consists of artificial neural network (ANN) and fuzzy feedback controller. ANN was trained by feedback error learning (FEL) to realize a feedforward controller. Although FEL can realize feedforward FES controller, target movement patterns are limited to those similar to patterns used in the training. In this paper, FEL-FES controller was tested in learning both random and cyclic movements through computer simulation of knee joint angle control with 4 different training data sets: (1) sinusoidal patterns, (2) patterns generated by low pass filtered random values, (3) using both the sinusoidal and the LPF random patterns alternatively and (4) patterns that consisted of 3 random sinusoidal components. Trained ANNs were evaluated in feedforward control of sinusoidal and random angle patterns. Training with data set (1) caused delay in controlling random patterns, and training with data set (2) caused delay in controlling sinusoidal patterns. Training with data set (3) showed intermediate performance between those with data set (1) and (2). Training with data set (4) could control adequately both random and sinusoidal patterns. These results suggested that generating movement patterns using sinusoidal components would be effective for various movement control by FEL-FES controller.

Takashi Watanabe, Naoya Akaike

A Hybrid BCI-Based Environmental Control System Using SSVEP and EMG Signals

The paper developed a hybrid Brain–computer interface (hBCI) home environmental control system for paralytics’ active and assisted living, by integrating single channel Electromyography (EMG) of occlusal movement and steady state visual evoked potentials (SSVEP). The system was designed as three-level interface, besides the idle state interface, for work state there are one main interface and five sub-interfaces. The main interface included five visual stimulus corresponding to different devices such as nursing bed, wheelchair, telephone, television and lamps, the sub-interfaces present control function of those devices. Gazing at stimuli at different frequencies corresponding to a certain function can select a device or device action. Several particular occlusal patterns respectively are used to confirm the selected function, return from sub-interface to main interface and switch on/off the system. Ten healthy subjects without any training completed the virtual system verification experiment, the averaged target selection accuracy based on SSVEP achieved 96.3%. Moreover with a simple clench action for target confirmation, the false positive rate was minimized to zero, which improved the control accuracy. This indicated that Combining SSVEP and EMG can effectively enhance the security and interactivity of the environmental control system.

Xiaoke Chai, Zhimin Zhang, Yangting Lu, Guitong Liu, Tengyu Zhang, Haijun Niu

Principal Component Latent Variate Factorial Analysis of MER Signals of STN-DBS in Parkinson’s Disease (Electrode Implantation)

Although clinical benefits of deep brain stimulation (DBS) in subthalamic-nuclei (STN) neurons have been established, albeit, how its mechanisms improve the motor features of PD have not been fully established. DBS is effective in decreasing tremor and increasing motor-function of Parkinson’s disease (PD). However, objective methods for quantifying its efficacy are lacking. Therefore, we present a principal component analysis (PCA) method to extract-features from microelectrode-recording(MER) signals of STN-DBS and to predict improvement of unified Parkinson’s disease rating scale(UPDRS) following DBS (applied on 12 PD patients). Hypothesis of this study is that the developed-method is capable of quantifying the effects-of-DBS “on state” in PD-patients. We hypothesize that a data informed combination of features extracted from MER can predict the motor improvement of PD-patients undergoing-DBS-surgery. This shows the high-frequency-stimulation in diseased-brain did not damage subthalamic-nuclei (STN) neurons but protect. Further, it is safe to stimulate STN much earlier than it was accepted so far. At the experimental level, high-frequency-stimulation of the STN could protect neurons in the subsstantia-nigra (SN, an important element of the brain). Therefore, to test this hypothesis in humans, we need to perform STN stimulation at the very beginning of the disease so that we can predict the disease at an early-stage. The latent-variate-factorial is a statistical-mathematical technique PCA based tracking method for computing the effects of DBS in PD. Ten parameters capturing PD characteristic signal-features were extracted from MER-signals of STN. Using PCA, the original parameters were transformed into a smaller number of PCs. Finally, the effects-of-DBS were quantified by examining the PCs in a lower-dimensional-feature-space. This study showed that motor-symptoms of PD were effectively reduced with DBS.

Venkateshwarla Rama Raju

Functional State Assessment of an Athlete by Means of the Brain-Computer Interface Multimodal Metrics

The estimation in real time of the functional and mental state level for the athlete during the loads is essential for management of the training process. New multimodal metric, obtained by means of the brain-computer interface (BCI), is proposed. The paper discusses the results of the joint usage of data from Emotiv EPOC+ mobile wireless headset. It includes motion sensors (accelerometer) and EEG channels. The features of the Emotiv EPOC+ interface allow to record the deviation of the head from the body axis, which provides an additional channel of information about the physical and mental (psycho-emotional) state of the athlete. Based on this data a new multimodal metric is calculated. Approbation of the metric was performed for functional stress studies on group of 10 volunteer subjects, including evaluations of the TOVA-test and the hyperventilation load. The joint application of different signals modalities allows to obtain estimates level of attention for these functional studies.

Vasilii Borisov, Alexey Syskov, Vladimir Kublanov

Experimental Setup for the Systematic Investigation of Infrared Neural Stimulation (INS)

Infrared neural stimulation (INS) gains growing interest both in electrophysiological research and for potential clinical applications, promising advantages like contactless operation, superior focality and hence spatial selectivity, and lack of electrical stimulation artifacts for nerve stimulation. We established an experimental setup for systematic investigation of relevant INS parameters, since little quantitative research for deeper understanding has been performed yet. Our customized setup facilitates the use of multiple fiber-based infrared laser systems of different wavelengths for remote stimulation, multi-site low-noise EMG recording and automated laser beam characterization. Hence, this setup simplifies upcoming systematic studies on both technical and physiological conditions for laser-induced neural activation. Determination of safe margins for reliable stimulation will help to understand the underlying physiological mechanisms and establish INS as alternative method for neural activation. Here, we present our experimental setup and preliminary results of our ongoing work.

Paul Schlett, Celine Wegner, Thilo Krueger, Thomas Buckert, Thomas Klotzbuecher, Ulrich G. Hofmann

Chronically Monitoring of Optogenetic Stimulation-Induced Neural and Hemodynamic Response

Understanding the link between neuronal activity and cerebral hemodynamics, known as neurovascular coupling (NVC), is critical for studying cerebral vascular dysfunctions. Optogenetics, which involves using light to control electrical activity of opsin-expressing neurons, is an approach to monitor and modulate functions of specific neurons in neuronal networks. Recent studies suggested that optogenetic stimulation induced hemodynamic response could be a good model for studying the mechanism of NVC. The aim of the study is to develop an optogenetic platform for long-term monitoring of the cerebral hemodynamics. An implantable optrode for optical stimulation and neural recording in addition to near-infrared spectroscopy (NIRS) recording have been developed. Through fiber optics, the optogenetic stimulation was introduced into ChR2-positive glutamatergic neuron of primary motor cortex (M1). Neural and hemodynamic responses were evaluated using local field potentials (LFPs) and NIRS recordings. An in-line optical filter was applied to filter off the blue light collected from M1 and to avoid interfering the NIRS measurement. The results showed the classic waveform of evoked hemodynamic response was obtained alongside of LFPs during optogenetic stimulation. Overall, our innovative optogenetic-NIRS interface could provide long-term observation on cerebral hemodynamics during optogenetic modulation.

Chun-Wei Wu, Jia-Jin Chen

System for Motor Evoked Potentials Acquisition and Analysis

Biological signal acquisition is a fundamental part of the following signal processing methods. This study is focused on hardware and software solution for an electrophysiological measurement in neurological patients and healthy controls. This paper deals with a design and an implementation of the system for transcranial magnetic stimulation (TMS) applied over the human motor cortex, which has the diagnostic and potential therapeutic effect, respectively. The system was successfully used for examinations of 22 neurological patients (mean age 51 ± (SD) 17 years) suffering from dystonia of various distribution and etiology treated by chronic deep brain stimulation of globus pallidus interna (GPi DBS). Established values of the motor-evoked potential’s (MEP) parameters are in line with the current literature. Designed system for TMS examination is an effective tool for studying the pathophysiology of neurological diseases.

V. Čejka, A. Fečíková, O. Klempíř, R. Krupička, R. Jech

Comparison Between Support Vector Machine with Polynomial and RBF Kernels Performance in Recognizing EEG Signals of Dyslexic Children

Dyslexia is seen as learning disorder that causes learners having difficulties to recognize the word, be fluent in reading and to write accurately. This is characterized by a deficit in the region associated with learning pathways in the brain. Activities in this region can be investigated using electroencephalogram (EEG). In this work, Discrete Wavelet Transform (DWT) with Daubechies order of 2 (db2) based features extraction was applied to the EEG signal and the power is calculated. The differences between beta and theta band with responding to learning activities were explored. Multiclass Support Vector Machine (SVM) was used to classify the EEG signal. Performance comparison of Polynomial and Radial Basis Function (RBF) kernel recognizing EEG signal during writing word and non-word is presented in this paper. It was found that SVM with RBF kernel performance was generally higher than that of the polynomial kernel in recognizing normal, poor and capable dyslexic children. The SVM with RBF kernel produced 91% accuracy compared to the polynomial kernel.

A. Z. Ahmad Zainuddin, W. Mansor, Khuan Y. Lee, Z. Mahmoodin

Photothermal Inhibition of Cortex Neurons Activity by Infrared Laser

Some brain diseases are caused by neurons being abnormally excited, such as Parkinson’s disease (PD) and epilepsy. The aim of this study was to investigate the feasibility and the efficacy of infrared laser irradiation for inhibiting neuronal network activity. We cultured rat cortex neurons, forming neural networks with spontaneous neural activity, on multi-electrode arrays (MEAs). To inhibit the activity of the networks we irradiated the neurons using different intensity of 1550 nm infrared laser light. A temperature model was created using COMSOL Multiphysics software to predict the temperature change at different laser intensity irradiation. Our initial result shows that the wavelength of 1550 nm infrared laser can be used to inhibit the network activity of cultivated rat cortex neurons directly and reversibly. The degrees of network inhibition can be manipulated by changing the laser intensity. The optical thermal effect is considered the primary mechanism during infrared neural inhibition (INI). These results demonstrate that INI could potentially be useful in the treatment of neurological disorders and that temperature may play an important role in INI.

Qingling Xia, Tobias Nyberg

Automated Atlas Fitting for Deep Brain Stimulation Surgery Based on Microelectrode Neuronal Recordings

Introduction: The deep brain stimulation (DBS) is a treatment technique for late-stage Parkinson’s disease (PD), based on chronic electrical stimulation of neural tissue through implanted electrodes. To achieve high level of symptom suppression with low side effects, precise electrode placement is necessary, although difficult due to small size of the target nucleus and various sources of inaccuracy, especially brain shift and electrode bending. To increase accuracy of electrode placement, electrophysiological recording using several parallel microelectrodes (MER) is used intraoperatively in most centers. Location of the target nucleus is identified from manual expert evaluation of characteristic neuronal activity. Existing studies have presented several models to classify individual recordings or trajectories automatically. In this study, we extend this approach by fitting a 3D anatomical atlas to the recorded electrophysiological activity, thus adding topological information. Methods: We developed a probabilistic model of neuronal activity in the vicinity the subthalamic nucleus (STN), based on normalized signal energy. The model is used to find a maximum-likelihood transformation of an anatomical surface-based atlas to the recorded activity. The resulting atlas fit is compared to atlas position estimated from pre-operative MRI scans. Accuracy of STN classification is then evaluated in a leave-one-subject-out scenario using expert MER annotation. Results: In an evaluation on a set of 27 multi-electrode trajectories from 15 PD patients, the proposed method showed higher accuracy in STN-nonSTN classification (88.1%) compared to the reference methods (78.7%) with an even more pronounced advantage in sensitivity (69.0% vs 44.6%). Conclusion: The proposed method allows electrophysiology-based refinement of atlas position of the STN and represents a promising direction in refining accuracy of MER localization in clinical DBS setting, as well as in research of DBS mechanisms.

Eduard Bakštein, Tomáš Sieger, Daniel Novák, Filip Růžička, Robert Jech

Applying Weightless Neural Networks to a P300-Based Brain-Computer Interface

P300-based Brain Computer Interfaces (BCI) are one of the most used types of BCIs in the literature that make use of the electroencephalogram (EEG) signal to convey commands to the computer. The efficiency of such systems depends drastically on the ability of correctly identifying the P300 wave in the EEG signal. Due to high inter-subject and inter-session variability, single-subject classifiers must be trained every session. In order to achieve fast setup times of the system, only a few trials are available each session for training the classifier. In this scenario, the capacity to learn from few examples is crucial for the performance of the BCI and, therefore, the use of weightless neural networks (WNN) is promising. Despite its possible added value, there are no studies, to our knowledge, applying WNNs to P300 classification. Here we compare the performance of a WNN against the state-of-the-art algorithms when applied to a P300-based BCI for joint-attention training in autism. Our results show that the WNN performs as good as its competitors, outperforming them several times. We also perform an analysis of the WNN hyperparameters, showing that smaller memories achieve better results most of the times. This study demonstrates that the adoption of this type of classifiers might help increase the prediction accuracy of P300-based BCI systems, and should be a valid option for future studies to consider.

Marco Simões, Carlos Amaral, Felipe França, Paulo Carvalho, Miguel Castelo-Branco

Biomaterials, Cellular and Tissue Engineering, Artificial Organs

Frontmatter

How Does Cell Deform Through Micro Slit Made by Photolithography Technique?

Several slits sort cell according to the deformability in vivo. A micro slit (0.87 mm of width, 0.010 mm height) was newly designed between a micro ridge on a transparent polydimethylsiloxane plate and micro ridges on a borosilicate glass plate. These ridges made by photolithography technique make contact each other in the perpendicular position to make the slit between the ridges. A one-way flow system was designed to observe each cell passing through the slit in vitro. Four kinds of cells were used in the test: C2C12 (mouse myoblast cell), HUVEC (human umbilical vein endothelial cell), Hepa1-6 (mouse hepatoma cell), and Neuro-2a (mouse neural crest-derived cell). The suspension of each kind of cells was injected to the slits. The deformation of each cell passing through the slit was observed with an inverted phase-contrast microscope. At the microscopic images, the outline of each cell was traced, and the area (S) was calculated. The deformation ratio was calculated as the ratio (S2/S1) of the projected area of each cell before the slit (S1) and that in the slit (S2). The velocity of the cell passing through the slit was calculated by the trace at the microscopic movie. The experimental results show that each cell deforms to the flat circular disk and passes through the micro slit. Hepa1-6 is flattened with the increase of the passing velocity, and HUVEC is elongated along the flow. The designed slit between micro ridges is effective to evaluate the deformability of cells.

Shigehiro Hashimoto, Yusuke Takahashi, Haruka Hino

Creation of Bio-Roots with Usage of Bioengineered Periodontal Tissue—a General Overview

Teeth are crucial for health and appearance. Loss of teeth leads to functional, psychological and esthetic issues. For many years, osseointegrated dental implants have been successfully used as a popular prosthetic restoration method for missing teeth. These implants have a direct connection with the alveolar bone, which can cause damage and affect the implant itself and the temporomandibular joint. Thus, those implants should be inspired by natural teeth, which possess periodontal ligament fibers—a connective tissue structure that has supportive, remodeling, sensitive and nutritive function. With advancement in the fields of tissue engineering and dental implantology, a great number of experiments is performed to reconstruct the periodontium around the titanium implants. The aim of this study was to examine studies published between 2000 and 2017, and the clinical benefits of such bioengineered implants. Research is based on full-length papers retrieved from PubMed/Medline electronic database using the key words ‘dental implants’, ‘regenerative dentistry, ‘tissue engineering’, ‘bioengineered periodontal tissue’, ‘tooth replantation’. After application of inclusion and exclusion criteria, 14 papers were selected and critically reviewed. In the following articles it was found that bioengineered dental tissue could be used as a successful therapy method with a focus on significant improvement in the quality of a patient’s life. Further studies are needed for the development of these novel approaches as they cannot be easily applied clinically for various reasons due to the complexity of wrapping periodontal ligament fibers around the dental titanium implants. In addition to this, aggravating factors for usage of such tissue engineering implants on the daily basis are most suitable in terms of costs and time required for practical applications.

Ahmed Osmanović, Sabina Halilović, Naida Hadžiabdić

In Vitro and in Vivo Hemolysis Tests of a Maglev Implantable Ventricular Assist Device

Objective: Implantation of a ventricular assist device (VAD) is a seminal therapeutic option for patients with terminal cardiac failure. A growing number of VAD patients are successfully bridged to transplantation, or can even live permanently with the device. However, the success is restricted by frequent severe complications. Haemolysis is a relevant adverse effect of several VAD types, which is the result of destruction of red blood cells, reduced by wall shear stress, flow acceleration and interaction with artificial surfaces. The CH-VAD, a small implantable continuous-flow blood pump, featuring a magnetically levitated impeller and enough hydrodynamic performance, was under development and completed for a 60-days animal implantation experiment in 6 sheep. The goal of this study is to validate the hemolysis of the pump through in vitro and in vivo studies. Methods: A series of in vitro tests was quantified experimentally by using in vitro circulation loop system according to ASTM F1841, the standard practice for the assessment of hemolysis in continuous-flow blood pumps. The hemolysis test in vivo was performed during a 60-days ovine model implantation, which was being conducted under the Institutional Animal Care and Use Committee (IACUC) protocol 05-0600 1. Results in vitro tests showed that the average normalized index of hemolysis (NIH) value of the VAD was 0.007 mg/l. The hemolysis in vivo was evaluated based on the amount of free hemoglobin in the plasma, and which showed that the free hemoglobin level in plasma peaked at 0.95 mg/l on the fifth postoperative day and then returned to an acceptable range of 6.0 mg/dL. Conclusion The magnetic levitation left ventricular assist device has good hemolytic performance. These acceptable performance results supported proceeding initial clinical trail conditions.

Keqiang Cai, Lianqiang Pan, Yuqian Liu, Guanghui Wu, Changyan Lin

Therapeutic Embolization by Cyanoacrylate Liquid Glues Mixed with Oil Contrast Agent: Time Evolution of the Liquid Emboli

Glue embolization is a minimally invasive treatment used to block the blood flow to specific targeted sites. Cyanoacrylate liquid glues, mixed with radiopaque iodized oil, have been widely used for vascular embolization owing to their low viscosity, rapid polymerization rate, good penetration ability and low tissue toxicity. In this study, we have conducted an in vitro study to quantitatively investigate the polymerization kinetics of two n-butyl cyanoacrylate (nBCA) glues (Glubran 2 and Histoacryl) mixed with an iodized oil (Lipiodol) at various concentrations. The polymerization process of the glue-oil mixture is systematically characterized upon contact with a protein ionic solution mimicking plasma and compared to the case without protein. The results provide essential information for interventional radiologists to help them understand the glue behavior upon injection, and thus control embolization.

Yongjiang Li, Dominique Barthes-Biesel, Anne-Virginie Salsac

The Biomaterial Surface Nanoscaled Electrical Potential Promotes Osteogenesis of the Stromal Cell

The calcium phosphate coating was provided onto the titanium substrate because of the nanoarc coatings technology. Both surface morphology and electrical charge of the coating were measured at the nano/micro-scaled lateral resolution. The negative electrical potential was typical for sockets, however the positive one to the peaks of the roughness. The cells were mainly attached at the negatively charged sockets. The cells expressed both osteocalcin and alkaline phosphatase that are the osteoblastic molecular markers.

Yuri Dekhtyar, Igor Khlusov, Yurii Sharkeev, Nataliya Polyaka, Vladimir Pichugin, Marina Khlusova, Fjodor Tjulkin, Viktorija Vendinya, Elena Legostaeva, Larisa Litvinova

Removal of Vascular Calcification Inducer Phosphate in Different Dialysis Treatment Modalities

Approximately 8–10% of the adult population in Europe suffers from kidney diseases. Cardiovascular complications are the leading cause of death in chronic kidney disease (CKD) patients, and vascular calcification is prevalent. High serum phosphate (P) level is a trigger of higher prevalence of vascular calcification in CKD patients. Phosphate is removed from the blood of end-stage renal disease (ESRD) patients regularly by extracorporeal renal replacement therapy, called dialysis. This paper aims to evaluate the calcification capability of CKD phosphate levels and compare the removal of phosphate during the different dialysis modalities. Human vascular smooth muscle cells and rat aortic rings were incubated in a medium containing CKD levels of phosphate. Both, calcium content measurements and histochemical staining proofed significantly increased calcification. Ten uremic patients, five males, and five females mean age 59 ± 16 years, were followed during 40 chronic midweek hemodialysis sessions. Four dialysis modalities with different settings were used once for each patient: hemodialysis (HD), high-flux hemodialysis (HF1, HF2) and postdilutional online hemodiafiltration (HDF). Total removed phosphate (TRP) was calculated by using phosphate concentration and the weight of the total spent dialysate collection. Phosphate reduction ratio (RR) was calculated by using patients’ pre- and post-dialysis phosphate concentrations in serum. Patients’ mean pre-dialysis serum phosphate levels were 1.72 ± 0.57 mmol/L, which is higher than in healthy subjects (0.81–1.45 mmol/L). Phosphate serum reduction ratios achieved during HD procedures were significantly lower from the ratios achieved during HDF and HF2 procedures. The mean total removed phosphate (TRP) values for HD were significantly lower than TRP values of other modalities (HF1, HF2, and HDF). Differences in removal values between HF1, HF2, and HDF were not significant. The results are indicating that phosphate levels presented in CKD increase vascular calcification and it is possible to remove phosphate more effectively by adjusting the dialysis treatment parameters.

Jana Holmar, Ivo Fridolin, Merike Luman, Joachim Jankowski, Heidi Noels, Vera Jankowski, Setareh Alampour-Rajabi

DNA Intracellular Delivery into 3T3 Cell Line Using Fluorescence Magnetic Ferumoxide Nanoparticles

Gene delivery is a widespread strategy in current experimental medicine. In this work, we report a method for low-toxic intracellular DNA vector delivery and post transfection localisation of this vector in mouse embryonic fibroblast cell lines. The surface of modified ferumoxide nanoparticles conjugated with Rhoda-mine B isothiocyanate (FeNV-Rh) was modified with linear polyethyleneimine and medium molecular weight chitosan to increase Accelerated Sensor of Action Potentials DNA vector adhesion. The size of the FeNV-Rh/DNA transfection complex was studied using dynamic light scattering (DLS) and scanning electron microscopy (SEM) techniques. The transfection complex internalisation of plasmid expression and FeNV-Rh, and stability of rhodamine fluorescence in intracellular space were observed at time periods 6, 12, 24 and 48 h post transfection. Results showed high transfection complex intracellular biocompatibility—cell viability after Rh-MNP labelling was higher than 97% 24 h after transfection, and higher than 95% after the next 24 h. Selective FeNV-Rh localisation in the lysosomes was quantified. More than 82% of nanoparticles were localised in the lysosomes 12 h post transfection and 94% of lysosomes had a significant and long-term deposit of nanoparticles. DNA vector expression was visible in >65% of the cells and precise protein localisation on the cell membrane was confirmed using confocal microscopy.

Ondrej Svoboda, Josef Skopalik, Larisa Baiazitova, Vratislav Cmiel, Tomas Potocnak, Ivo Provaznik, Zdenka Fohlerova, Jaromir Hubalek

Modern Semi-automatic Set-up for Testing Cell Migration with Impact for Therapy of Myocardial Infarction

Ischemic heart disease and resulting acute myocardial infarction (AMI) is one of the main causes of morbidity and mortality in industrial countries. The idea for the modern therapeutic strategy, which should activate the migration of stem/progenitor cells or reduce the migration of inflammatory cells in AMI regions, has emerged in the last 15 years, mainly as a result of physiological observation and post-mortem histology. Published data from direct measurements of cell migration are very limited. We prepared a universal set-up that can be used for the testing of cell migration in AMI micro-environment. Mesenchymal stromal cells (MSCs), the most commonly used stem/progenitor cells in experimental cellular therapy for AMI, were used in the recent set-up tests. The cells, which should be tested for their migration potential, were injected into the starting point in a special micro-chamber on the substrate, and optics of the microscope allowed a time-lapse recording of cells in micrometre resolution every 2 min. Our software tools provided precise 2D and 3D tracking of moving cells and data export for statistical analysis. Set-up should be upgraded to a fully-automatic preclinical screening tool in the future.

Larisa Baiazitova, Josef Skopalik, Vratislav Cmiel, Jiri Chmelik, Ondrej Svoboda, Ivo Provaznik

Recent Research Progress on Scaffolds for Bone Repair and Regeneration

Currently, the major areas of research in nanotechnology with potential implications in ostearticular regeneration are: nano-based scaffold construction and modification to enhance biocompatibility, mechanical stability, and cellular attachment/survival. Nanotechnologies can be used to form scaffolds and to deliver drugs and growth factors in the lesion site in order to enhance bone formation. The aim of this paper is to give an overview of some recent advances of osteoarticular tissue engineering allowed by the application of nanotechnologies.

Stefano Nobile, Lucio Nobile

µCT Based Characterization of Biomaterial Scaffold Microstructure Under Compression

Scaffolds are often designed with progressive degradation to make way for cell proliferation of seeded cells for native tissue. The viability of the scaffold has been shown to depend on, among other things, the microstructure. Common parameters, that are used to describe microstructure, are porosity, material thickness, pore size and surface area. These properties quantify the suitability of the scaffold as a substrate for cell adhesion, fluid exchange and nutrient transfer. Bone and cartilage scaffolds are often placed or operated under loads (predominantly compression). This can alter the structural parameters depending on the stiffness of the scaffold and applied deformation. It is important to know, how scaffolds’ parameters change under deformation. In this study, two scaffolds (PLCL-TCP and collagen-PLA) intended for use in bone and cartilage applications, were studied through micro computed tomography based imaging and in situ mechanical testing. The scaffolds were subjected to uniaxial compressive deformation up to 50% of the original size. The corresponding changes in the individual scaffold bulk characteristics were analyzed. Our results show an expected decrease in porosity with increasing deformation (with PLCL-TCP scaffold 52% deformation resulted in 56% decrease in porosity). Especially in the sandwich constructs of collagen-PLA, but also in PLCL-TCP composites, it was evident that different materials are affected differently which may be of significance in applications with mechanical loading. Our results are a step towards understanding the changes in the structure of these scaffolds under loading.

Markus Hannula, Nathaniel Narra, Kaarlo Paakinaho, Anne-Marie Haaparanta, Minna Kellomäki, Jari Hyttinen

Assitive Technologies

Frontmatter

Multi-gaussian Decomposition of the Microvascular Pulse Detects Alterations in Type 1 Diabetes

Among diabetic patients, microangiopathy represents a relevant cause of morbidity and mortality. Diabetes induces detrimental changes in the biomechanical characteristics of blood microvessels, and fuels the development of a dysfunctional vascularization. Since the structural properties of the circulatory system affect the microvascular pulse, the aim of this study was to detect these vascular alterations through a model-based quantitative analysis of its waveform. Baseline microvascular perfusion was recorded on the hallux with a laser Doppler flowmeter. 54 healthy subjects (age: 34 ± 26 years) and 22 type 1 diabetic (T1D) patients without known cardiovascular complications and smoking history (age: 34 ± 17 years) were compared. A novel multi-Gaussian decomposition algorithm was applied to reconstruct the heartbeat-related oscillations, which were evaluated according to normalized and physiologically-motivated shape descriptors. Eight out of the nine properties assessed significantly differed between the groups (p < 0.001), indicating that the proposed pulse modeling method is sensitive to the effects of T1D on the peripheral perfusion.

Michele Sorelli, Antonia Perrella, Piergiorgio Francia, Alessandra De Bellis, Roberto Anichini, Leonardo Bocchi

GOAL (Games for Olders Active Life): A Web-Application for Cognitive Impairment Tele-Rehabilitation

Vascular Dementia (VaD) and Alzheimer’s Disease (AD) are the major causes of advanced cognitive decline. Serious Games (SGs) are computer games, recently proposed in the healthcare sector, specifically for the evaluation and rehabilitation of psychiatric and neurological disorders. The main objective of the GOAL project is to test a suite of SGs on a group of subjects with Mild Cognitive Impairment (MCI) and Vascular Cognitive Impairment (VCI), conditions at risk of frank dementia, with the aim to characterize and quantify their functional, cognitive and motor abilities. The games were implemented using “ad hoc” ICT tools, for longitudinal monitoring and rehabilitation management directly from home. In this context, the Web-Application GOAL-App was developed for allow patients to access to scheduled physical and cognitive trainings. HTML5, JavaScript and CSS have been used to create a clear, intuitive and extremely easy to use UI. The back-end is JAVA-based. The preliminary results showed good feedback from the subjects, who regularly practiced the proposed scheduled trainings.

Leonardo Martini, Federica Vannetti, Laura Fabbri, Filippo Gerli, Irene Mosca, Stefania Pazzi, Francesca Baglio, Leonardo Bocchi

TangoTM Wellness Motivator for Supporting Permanent Lifestyle Change

We present a system designed for assisting people in obtaining healthier lifestyle. The system includes a monitoring device worn on the chest and a web portal that visualizes the measured parameters and provides the user motivating tips for healthier lifestyles. The monitored parameters include heart rate, step count, calorie consumption, activity level, heart rate variability and sleep quality. A unique feature of the system is that the communication from the wearable unit to the backend server is arranged via direct mobile network connection, thus avoiding the need for a separate gateway device. The measured data can be viewed with a web browser user interface. We evaluated the beat-to-beat heart rate estimation performance with ten subjects in a controlled exercise protocol and with three subjects in 24-h free-living conditions. The average mean absolute error of the R-R interval estimation was 8.0 ms and 6.4 ms in the two test scenarios, respectively and the corresponding coverages of the obtained R-R intervals 76% and 94%.

Antti Vehkaoja, Jarmo Verho, Mikko Peltokangas, Teppo Rantaniva, Vala Jeyhani, Jari Råglund

Measuring the Response of Patients with Type I Diabetes to Stress Burden

The article presents measurement methodology and systems for measuring and evaluating the response of patients suffering from type I diabetes to stress burden. The proposed methodology and systems have been developed to recognize the effects of strain on patients’ reaction time and their work performance. Stress burden was measured by a multi-sensory monitoring system designed for this purpose. The methods used were based on monitoring physiological stress symptoms by measuring pulse rate, respiratory rate, temperature, galvanic skin resistance, and electrical activity of muscles. It was suggested to monitor the measured parameters in waveform, from initiation of stress stimuli, throughout the period of growth, and up to the point of decline. The research was conducted under the supervision of psychologists, and the proposed methodology for measuring stress burden and its impact on physiological functions of type I diabetics involved a group of patients and a control group of healthy subjects. The proposed measurement methodology would be beneficial not only in the design of systems for detecting mental stress, but also in the treatment of patients suffering from diabetes and the assessment of their physical/mental state while performing demanding work tasks.

Vit Janovsky, Patrik Kutilek, Anna Holubova, Tomas Vacha, Jan Muzik, Karel Hana, Pavel Smrcka

Wearable Sensors and Domotic Environment for Elderly People

Technology is an important instrument for a new concept of home care and continuous monitoring. New and smaller devices and communication advances have constructed a more humanitarian model of assisted alternative to hospital. For this purpose an integral scheme must to consider physiological, emotional, social and environmental conditions that promote the multidisciplinary support for the patients. In this work we present an Integral Assistive Home Care System, specially designed for elderly or chronic illness people. The approach proposed comprises a user wearable device, a domotic system’s core installed in a personal computer (PC) and an ichnographic software (SICAA) that allows the interaction of the patient with the environment and peripheral devices. Wearable sensors system have a master module that deals with data acquisition, synchronization and wireless transmission, connected to sensors or slaves which acquire biological signals and process them to minimize the amount of data to be transmitted by Bluetooth. The biologic variables (each with its own specific acquisition and preprocessing module) acquired are temperature, heart rate and pulse oximetry, and kinetics measurements through an inertial sensor IMU. The domotic SICAA soft and control hardware was designed to achieve some automatic tasks through an ichnographic software. The programmed functions comprises: house control (that comprises blinds, lights, orthopedic bed, air conditioner, television, and intercom); medication alarm; career communication (nurse call, voice synthesizer), and computer access (internet, chat, games, and text processors). The entire system is low cost, modular and adaptable for different user’s capabilities and pathologies.

Sergio Ponce, David Piccinini, Sofía Avetta, Alexis Sparapani, Martín Roberti, Nicolás Andino, Camilo Garcia, Natalia Lopez

Videogame Implementation for Rehabilitation in Patients with Parkinson Disease

The present paper is focused on the rehabilitation of patients with Parkinson Disease (PD), using video games that respond to the movements of the player. It is important, to begin reviewing the state of the art, to delimit the characteristics of the system. Subsequently, the system was designed and implemented for use with software Unity and Arduino. Finally, the validation tests of the system were performed with patients of the PD and healthy patients. First, a review of the theoretical framework of Parkinson’s disease, rehabilitation, and videogames present today is carried out, analyzing advantages and disadvantages of the different systems existing in the market. Then, the characteristics that the game must fulfill are defined, such as the transmission technologies, methodologies to be implemented, equipment and software that will be used for the design. Next, the videogame design is done using the Unity software, the same one that allows to export it to the Android platform. The system consists in acquiring patient data using a Bluetooth module and an accelerometer, whose data results from the game are sent wirelessly to the mobile device, for the project were used a smartphone. The “Rehabilitation” application contained PlaneGame with three levels and BallGame with two levels of participation. Finally, the validation of the system and analysis of results were executed, where the tests are carried out at the “Adulto Mayor” (elderly) University. In conclusion, the results at the end of the rehabilitation sessions showed that the developed system improves the motor movements of the upper extremities, which favors raising the life quality of patients.

F. Chacha, J. P. Bermeo, M. Huerta, G. Sagbay

Design of a Multisensory Room for Elderly People with Neurodegenerative Diseases

Multisensory stimulation in older persons is an effective practice that helps to train the mind and motor skills through elements that stimulate the senses of the people. The spaces where specialists work the sensory stimulation are the so-called multisensory rooms “Snoezelen”. Initially, the use of these rooms was mainly intended for children with learning difficulties, those that had difficulties to explore their environment. Recently, last few years, there have been realized investigations of the implementation of these rooms in persons who present cognitive deteriorations from moderate to severely and neurodegenerative pathology as Parkinson’s, Dementia, Alzheimer’s, Huntington’s, Bipolar disorder, among others. This project developed and implemented a Multisensory Black Room for older patients with neurodegenerative diseases and cognitive impairment. Different sensory stimulus were used to help the cognitive and functional sphere of older people. The implemented room has some elements: stairs of colors, star curtain, fiber optic shower, textures path, virtual reality glasses and sound therapy. We test our room with a group of older people, some of them form a control group without room stimulation and the others used the room during 3 months. The results indicate that it has been possible to reduce the aggressiveness pattern and to evolve in the functional part (fine-gross motor) and focus the attention that was dispersed in patients with neurodegenerative diseases and cognitive impairment in the early and late stages. In addition, patients improve the relationship with their social and personal environment, since the initiative of the room is to provide an atmosphere of wellness and relaxation, for the patient and the specialist.

F. Duchi, E. Benalcázar, M. Huerta, J. P. Bermeo, F. Lozada, S. Condo

Feasibility Study of a Methodology Using Additive Manufacture to Produce Silicone Ear Prostheses

In the current years, many kinds of prostheses have been developed to replace parts with deformity or absent from the human body. Facial prosthesis production methods have undergone little change in the last 40 years. Today, manual techniques are used to produce prostheses, which are usually cast in wax over a replica of the patient’s anatomy. Silicone is the most appropriate structural material used in the production of atrial prostheses due to its mechanical and chemical characteristics. Recently, new technologies, such as 3D scanning and additive manufacturing techniques are being applied in the production of auricular prostheses with better cost/quality relation when compared to the manual manufacturing process. In this research, four methods to acquire the structure of a human ear were investigated (photogrammetry, 3D scanning, 3D reconstruction of computed tomography images and parameterized 3D modeling) to produce auricular prosthesis molds by additive manufacture using the fused deposition modeling (FDM) technique. The best silicone ear prosthesis produced shows an excellent esthetic result with 0.1–3% of dimensional error. Mechanical analysis of the silicone (tensile strength and hardness tests) shows that the prostheses produced have excellent mechanical resistance that is not altered by the pigmentation process. The research demonstrates the feasibility of an accessible methodology to produce ear prostheses using free software, technologies and supplies available in the market.

Barbara Olivetti Artioli, Maria Elizete Kunkel, Segundo Nilo Mestanza

Plantar Pressure Measurement Transformation Framework

Pedobarography measurements of pressure distribution across the plantar surface can be a source of valuable information for gait analysis in context of injury prevention, improvement in balance control, diagnosing disease, and gait analysis. Different applications demand different measurement types: platforms in the gait labs or in-shoe smart soles, and subsequent analysis methods vary with the application domain. Although the pedobarography is considered experimental, technology advancements in the field of IoT, and popularity of collecting different data linked to human activities and behavior, are contributing to increase in pedobarography research. Comprehensive analysis of research results is impeded since the data collecting is not standardized, and differ in volume and structure, thus not facilitating comparative analyses, as it is a case with other biomedical signals as ECG or EEG. In our research we have implemented software framework in Python language with objective to extract relevant pedobarography information using foot segmentation and data aggregation algorithms. In order to validate our solution we processed data from public plantar pressure data set and transformed it in data sets comprising pressure signals covering selected number of foot segments, down to one sensor signal. The proposed data transformation application can help in data sharing and comparison of different approaches in pedobarography.

Dusanka Boskovic, Iris Kico, Abdulah Aksamovic

Body Tracking Method of Symptoms of Parkinson’s Disease Using Projection of Patterns with Kinect Technology

The analysis of the body movement is relevant in different areas, such as therapy, rehabilitation, bioinformatics and medicine. The Parkinson’s disease (PD) is a progressive degenerative process of the central nervous system that primarily affects the movement. To measure motor disorders, body sensor networks and portable technologies are the trend for tracking and monitoring symptoms in PD. Through the use of technological tools, such as sensors, whether sensors for movement acquisition (accelerometers, gyroscopes, inclinometers) or environment sensors (sensors that record physiological properties), it is possible to track the symptoms of Parkinsonism in a person. A system has been designed using a Kinect sensor, that uses the projection of patterns technology for monitoring change in body posture, obtaining information for a set of points or joints, and variation that could have during the observed period. The designed Kinect sensor system consists of four modules: the first acquisition of the body movement of the patient with the Kinect sensor V1.0, the second feature extraction module to process captured scene by Kinect V1.0, the third recognition of the skeleton module and finally the acquired data processing module, developed with MatLab. The acquisition of the center of mass with the presented methodology, through projection of patterns used by the Kinect sensor technology, is non-invasive a method and convenient to use in people.

Raquel Torres, Mónica Huerta, Roger Clotet, Giovanni Sagbay

A Parametrization Approach for 3D Modeling of an Innovative Abduction Brace for Treatment of Developmental Hip Dysplasia

Developmental hip dysplasia (DHD) is frequently encountered in the pediatric orthopedic practice. DHD is characterized by dislocation of the femoral head in the acetabulum. In Brazil are diagnosed three times more cases than the world average (5–8 cases for 1,000 births). The lack of treatment leads to long-term morbidity, abnormal gait, chronic pain and arthritis. Early detection and treatment with a Pavlik harness results in improved outcomes. After 6 months of age, closed or open reduction with spica casting is required for 4 months to treat a persistent hip dislocation. Plaster is used for orthopedic immobilization due the low cost, moldability and good mechanical resistance. However, there are several risks and complications due to the use of spica cast in DHD treatment: Skin problems due to lack of adequate hygiene (itching, ulceration, dermatitis and infection), formation of pressure areas, plaster fracture (11% of cases) and fever. Digitization techniques have been explored for production of customized hip abduction brace by additive manufacturing. However, it is not possible to keep a child standing still to perform 3D scanning of the hip and legs region. The goal of this research was to develop an alternative approach for acquisition of the external geometry of the infant to create 3D model of an abduction brace. The parameterization technique created includes: The creation of a virtual 3D model of a child’s body using the MakeHuman software; Articulation of the hip region of the model to the position required in the treatment of DHD with the Blender software; Definition of the parameters required for the modeling of a hip abduction brace. A DHD pediatric orthopaedist approved the methodology created. Innovations in the area of assitive technology can bring many benefits to the user in the process of rehabilitation.

Natalia Aurora Santos, Barbara Olivetti Artioli, Ellen Goiano, Maraisa Gonçalves, Maria Elizete Kunkel

Biological Effects of Electromagnetic Fields

Frontmatter

ApOtEl: Development of a Software for Electroporation Based Therapy Planning

The objective of this paper is to describe the implementation of a software application, called ApOtEl, developed for needle electrodes positioning optimization for electrochemotherapy procedures in the treatment of cutaneous and subcutaneous tumors. The software was developed using MATLAB®, and it optimizes the needle-type electrodes positioning configurations, through the study of the analytical electric field, using Laplace equation in a homogeneous bi-dimensional environment. The optimization was based on requirements chosen to guarantee the tumor total coverage and to minimize healthy neighboring tissues damage. An optimization function was created to orientate the electrochemotherapy application, and the best option available in all configurations generated by the distance variations between electrodes and positioning orientations was determined. The software provides, by the entry of tumor dimensions, the optimized distances for positioning needle-type electrodes, as well as the representation of the electric field distribution and intensity. Representation of the electrodes positioning and instructions for the procedure to facilitate the procedure planning are provided.

Luisa Endres Ribeiro da Silva, Marcos Tello, Dario F. G. de Azevedo, Ana Maria Marques da Silva

Physical Analysis of Pulse Low-Dynamic Magnetic Field Applied in Physiotherapy

This article makes an effort to explain some physical and energy aspects of practice using magneto therapy in the treatment of the musculoskeletal system (orthopaedic surgery, physiotherapy and the rehabilitation). We are presenting the principles of electromagnetic induction in muscle tissue as typical example of the parts of human body. The main accent of presenting theory is put on macroscopic physical behaviour of low-frequency electromagnetic field in living body parts. The problems are indicated with modelling. This approach use simplified model of tissue conductivity. One of the goals is to warn about different distribution of magnetic field in parts of body caused by different position, spatial orientation and metal implants too. The each metal part implanted into human body has strongly influence on distribution physical effects into. Another analyse introduces physical and energy differences among individual types of power sources of magnetic field and their dynamic behaviour.

Aleš Richter, Miroslav Bartoš, Želmíra Ferková

Clinical Engineering

Frontmatter

Analyzing Energy Requirements of Meta-Differential Evolution for Future Wearable Medical Devices

Recent advances in clinical engineering include development of physiological models to deliver optimized healthcare. Physiological model comprises a number of equations to relate biomedical signals. Each equation contains a set of coefficients. Determining the coefficients is a complex task as the models are non-linear. Therefore, development of the models must be accompanied by a development of methods to determine model coefficients. With the advent of wearable medical devices, we have to consider energy requirements of the models and the methods. Considering an illustrative case of type-1 diabetes mellitus patients, we already demonstrated that Meta-Differential Evolution outperforms analytical methods, when determining coefficients of glucose dynamics. In this paper, we analyze convergence of the Meta-Differential Evolution, running time and associated power consumption on a single board computer with a system-on-a-chip—Cortex-A8 AM335x. Based on the analysis, we recommend splitting the process of determining the coefficients into two phases. First phase determines the initial, per-patient optimized coefficients. Second phase is an energetically efficient update of these coefficients with new, continuously measured signal of the patient. Meta-Differential Evolution searches for optimal coefficients by evolving a number of generations of candidate coefficients, using a number of evolutionary strategies. We demonstrate that the proposed approach significantly reduces the number of candidate coefficients to evaluate, while achieving the desired accuracy. This positively reflects in the lifetime of wearable device’s battery. Specifically, calculating coefficient’s update took 0.05 Ws only. It shows the feasibility of using Meta-Differential Evolution with its improved accuracy for blood glucose calculations in a wearable device.

Tomas Koutny, David Siroky

Energy Consumption Profiles of Common Types of Medical Imaging Equipment in Clinical Settings

Imaging equipment such as MRIs, CT scanners and general radiography equipment consume significant amounts of energy while operating. This study describes a series of detailed energy consumption studies on these devices during clinical use at three major health care centres in Canada, one in British Columbia and two in Ontario. The study was conducted by the Canadian Coalition for Green Health Care [1], with funding provided by Natural Resources Canada [2] and BC Hydro [3]. The primary goal of the study was to accelerate the development of ENERGY STAR specifications for medical imaging equipment. Natural Resources Canada is assisting the United States Environmental Protection Agency (US EPA) [4], by collecting these data from the field. Eight testing events were undertaken, providing energy consumption data for low power energy modes, standby/idle power energy modes and active/patient scanning energy modes. Energy consumption was measured over periods ranging from three to eleven days, to provide rich information about when and how frequently the equipment was used and what the associated energy consumption profiles were. Data acquisition rates were varied to gain a detailed understanding of the temporal variations in energy consumption profiles during each use mode. Results from this study showed that there were variations in the low power mode energy consumption of greater than 25% in some cases, and that non-scanning energy consumption, either low power or stand-by modes, in some cases accounted for up to 80% of the total energy consumption of the system at some hospitals. These findings indicate that there is considerable scope for manufacturers to reduce the energy consumption levels of their devices, and for users to reduce energy consumption during clinical use through practices such as placing the system into a lower energy mode or shutting it down while not in use, where possible.

Anthony Easty, Linda Varangu, J. J. Knott, Shawn Shi, Kent Waddington

Automated Sunglasses Lens Exposure Station and the Preliminary Effects of Solar Exposure

The Laboratory of Ophthalmic Instrumentation (LIO) from the University of Sao Paulo—Brazil, is involved in research about Sunglasses and its standards, and has already contributed for changing parameters in the previous Brazilian sunglasses standard, the ABNT NBR 15111-2013. The focus of the work presented in this paper is to investigate on the long-term solar exposure effects in sunglasses lenses and to conduct this study, we have developed an automated exposure system dedicated to expose sunglasses lenses towards the sun. The system also measures the dose of ultraviolet radiation which the lenses were subjected to and other weather variables, like temperature and relative humidity of the air. In this paper, we discuss about the materials used to manufacture sunglasses lenses, about the machine we developed to exposes the lenses and the methods used to measure the lenses transmittance characteristics over the time and to determine if and how long-term solar exposure may affect the samples.

Leonardo Mariano Gomes, Artur Duarte Loureiro, Guilherme Andriotti Momesso, Mauro Masili, Liliane Ventura

Experience in the Design of Temporary External Pacemaker in the Case of the Mexican Institute of Social Security (IMSS)

The present paper shows the design and development of the external pacemaker circuit, for use in diagnose or research of diseases than affect the heart. In this case they used lineal circuit, existent in the Mexican National Market. We design and used a simple prototype for generation pulse for heart stimulation by employing the oscillators with the circuit LM555. Previous results obtained in HGR1 “Carlos Macgregor” hospital displayed good operation in the electrical impulses from the heart muscle cause your heart to beat (Contract). Build up this type of pacemaker is the objective, in this paper we show how was the development of a circuit that cold sense the heart rhythm and could supply the impulses necessaries to live. The most relevant is your use in medical persons of the hospital as diagnose and research tool.

Gustavo Adolfo Martinez Chavez

Prototype Device for Driving Suitability Tests in Sunglasses

Wearing inadequate sunglasses while driving may lead to dangerous misunderstandings in objects and traffic lights recognition. Sunglasses standards propose transmittance requirements that sunglasses should fit to be classified as suitable for driving. Transmittance tests are time-consuming and laborious. Also, it requires a spectrophotometer and a skilled technician to be performed. The aim of this study was to develop and to build an easy-to-use, quick and accurate device for luminous and traffic lights transmittance tests which runs the tests by itself in a way anyone can operate it without any training. A microcontrolled prototype was developed and built using a white LED and a four-channel sensor combination. This combination generated luminous and traffic lights weighting functions similar to standard ones. Using our prototype and a gold standard (VARIAN Cary 5000 spectrophotometer), luminous transmittance and relative attenuation quotients for traffic lights were measured in 128 sunglasses lenses. Bland-Altman method was used to assess concordance between both measurement methods. The bias was insignificant for all measurement and the limits of agreement were broad for luminous transmittance and for relative attenuation quotient for blue light detection, and narrow for the others. Thus, within the predefined tolerance, prototype measurements are equivalent to gold standard ones for relative attenuation quotients for red, yellow and green light detection. Despite not all prototype measurements being equivalent to gold standard ones, results were accurate; only 5 from 128 lenses were defectively classified as to suitability for driving (2 for luminous transmittance, 1 for red light quotient and 2 for blue light quotient). Our prototype creates means to general public to assess characteristics of their own sunglasses including whether they are suitable for driving according brazilian and ISO standards.

Artur D. Loureiro, Liliane Ventura

Using the Monte Carlo Stochastic Method to Determine the Optimal Maintenance Frequency of Medical Devices in Real Contexts

The purpose of this study was to implement and validate a Monte Carlo Algorithm (MCA) to determine the best T value (the time between two preventative maintenances) that optimizes the achieved availability of equipment types. In doing so, we (1) collected 796 maintenance works orders from 16 medical devices installed in a 900-bed hospital; (2) we fitted the probability distributions for each of the inputs of the achieved availability mathematical model (the mean preventative and corrective service time (in hours)); (3) we generated a set of random inputs following a Weibull distribution of the achieved availability mathematical model; (4) we calculated the achieved availability for every random input generated; this process was repeated for “m” iterations (an accuracy of 1%, 95% CI, alpha = 0.05); (5) the trends of the mean achieved availability for the different maintenance T intervals versus mean time to failure (MTTF) for all the equipment types were plotted; finally, (6) the best T value with the maximum value of the achieved availability of a medical device type for a specific MTTF was the optimal target. The mean simulation time for all the cases was 12 min. The MCA was able to determine the best T value, optimizing the achieved availability in 81.25% of cases. In conclusion, the results showed that, on average, the T maintenance intervals determined by the MCA were statistically significantly different from the original T values suggested either by the clinical engineering department or third-party maintenance providers (MCATmean = 1.68 times/yr, ActualTmean = 2.56 times/yr, p = 0.008).

Antonio Miguel-Cruz, Pedro Antonio Aya Parra, Andres Felipe Camelo Ocampo, Viena Sofia Plata Guao, Hector H. Correal O, Nidia Patricia Córdoba Hernández, Angelmiro Núñez Cruz, Jefferson Steven Sarmiento Rojas, Daniel Alejandro Quiroga Torres, William Ricardo Rodríguez-Dueñas

The Supportability of Medical Devices

Clinical Engineering (CE) and Health Technology Management (HTM) appears to be spending more time trying to get medical device manufacturers to provide support for inhouse servicing than ever before. Surveys conducted by AAMI in 2015 and CMBES in 2016 revealed that model-specific technical training and documentation were the top two priorities for this group of respondents. Many manufacturers and even healthcare institutions seem to minimize the value or even the existence of CE/HTM programs. It is important to note that these programs operate to save hospitals and healthcare money and also serve to provide quick and necessary support for healthcare technology in the clinical setting. They are now being challenged by many of their commercial partners. Almost every other acquisition of medical equipment now requires the need to negotiate support for inhouse services and is met with a balance of success and failure. It appears manufacturers are designing equipment without considering the customer’s option to service it. These customers include medium to large hospitals that have the capacity, economies of scale, and know-how to create and sustain CE/HTM departments. At the same time, there are many companies that provide good support for inhouse servicing. Their examples of appropriate support strategies may serve as a baseline for most other companies to make their products serviceable and to ensure CE/HTM is qualified and properly equipped to perform the required service. This paper highlights most of the issues surrounding the notion of Supportability in the CE/HTM world. These issues affect independent service organizations (ISOs) in a similar way. There are efforts to manage the supportability issue and ideas on how certain barriers might be dealt with. The paper attempts to recognize these and the rationale behind certain behaviors. There are standards and regulations, or an absence of them, which either help or hinder the issue.

M. Capuano

Smart Tourniquet System for Military Use

Extremities are the most frequently injured regions of body encountered with the combat casualties. The extremity hemorrhages constitute the leading cause of preventable deaths in the first aid period. Thus, tourniquets are indispensable devices for combat casualty care. There are some military tourniquets, which are produced worldwide and can be manually applied by the wound to prevent blood loss. However, in military applications, there is no tourniquet system comprising these features that can be used with one hand, can be applied quickly and transmits information. We have developed a tourniquet system which applies the required pressure to the extremity of the person by moving a belt connected to the pulley with a motor. When the arm or leg buttons on the device are pressed, the system is activated. Once the belt is fitted to the extremity, the system automatically starts the tourniquet process and is continued until the bleeding is stopped. The information of the blood flow and force applied are acquired via the feedback from the motor encoder and the force sensor. The system starts the tourniquet process and the bluetooth transmits the location and application time of the tourniquet. The receiver informs the headquarters via the military communication standard. In this respect, it is possible to be informed about exact location of the injured soldiers in the hot zone. In order to test the developed tourniquet, we have produced the leg phantoms which consist of femur bones and plastics similar to in actual dimensions of the human leg and artificial veins. Tourniquet operation was applied to the point where the tourniquet operated blood flow stopped. It is thought that the developed system will be used in military applications and internal security.

Erdem Budak, Faruk Beytar, Aytekin Ünlü, Osman Eroğul

Using Data Mining Techniques to Determine Whether to Outsource Medical Equipment Maintenance Tasks in Real Contexts

The purpose of this study was to determine whether the maintenance of medical equipment should be outsourced (or not). For this, we used data mining techniques called decision trees. We (1) collected 2364 maintenance works orders from 62 medical devices installed in a 900-bed hospital; (2) then we randomly selected 90% of the maintenance works orders to train 8 different decision tree schemas (J48 (pruned and unpruned), Naive Bayes tree, random tree, alternating decision tree, logistic model tree, decision stump, REP tree); (3) next, the remaining 10% of the works orders were used to test the decision tree schemas. The relative absolute error was used to evaluate what the tested decision tree schemas had learned; finally (4), we chose the decision tree schema with the lowest relative absolute error. Overall, the decision tree schemas performed well. 62.5% (5/8) of the decision tree schemas had less than 20% relative absolute error. 87.5% (7/8) of the decision tree schemas had more than 90% in the correct classification (whether to outsource maintenance tasks or not). The different tested decision tree schemas showed that the most important variables when making the decision whether to outsource maintenance tasks or not were: medical device, risk class (I, IIA, IIB, III), complexity, obsolescence, maintenance frequency, service time and outsourcing. The best decision tree schema was the logistic model tree (LMT) with 14.6628% relative absolute error and 94.7034% in the correct classification.

Antonio Miguel-Cruz, Pedro Antonio Aya-Parra, William Ricardo Rodríguez-Dueñas, Andres Felipe Camelo-Ocampo, Viena Sofia Plata-Guao, Hector H. Correal O., Nidia Patricia Córdoba-Hernández, Angelmiro Nuñez-Cruz, Jefferson S. Sarmiento-Rojas, Daniel Alejandro Quiroga-Torres

Set Up for Irradiation and Performing Spectroscopy for Human Lenses

Introduction: In the environment with natural solar irradiation, the part of the electromagnetic spectrum that should be most attentive when it comes to eye health is the ultraviolet. Studies with both animals and cells have shown that chronic exposure of the eyes to ultraviolet radiation (UVR) causes significant damage to the eyes structures, particularly the cornea, lens, and retina. Unfortunately, still today, there is controversy regarding the harm caused to the human eye due to exposure of the ocular environment to UVR. There is great methodological difficulty with the use of human lenses, which leads to the increase of controversial results. Aim: Development of a device for that the human lens can be irradiated in a solar simulator and analyzed in spectrophotometer for determination of the UVR effects in the eye. Methodology: A lens holder has been developed using a mathematical model and a 3D printer. Results: The result obtained after ZMorph 3D printer was a very light and effective holder for fitting the lenses as well as the cuvette. Conclusion: The development of this holder will allow different experimental protocols to be performed with the human lens, once this support decreases the need for excessive manipulation of the lens in relation to other supports found in the literature, avoiding the degradation of the tissue. We believe that the development of this holder will contribute in a promising way for future research with human lens, assuring reliable results. Financial support: FAPESP (2013/08038-7 and 2014/16938-0).

Fernanda Oliveira Duarte, Márcio Makiyama Mello, Mauro Masili, Liliane Ventura

Global CE Success Stories: Overview of 400 Submissions from 125 Countries

Health Technology (HT) is vital to global health care. The dependence of health, rehabilitation, and wellness programs on technology for the delivery of services has never been greater. It is essential that health technology be optimally managed. Clinical and biomedical engineers have been recognized by WHO as essential to providing this management. At the 1st International Clinical Engineering and HT Management Congress and Summit held in China in 2015, a resolution was adopted by the global Clinical Engineering (CE) country participants to identify and promote our unique qualifications, and to record the CE contributions to the improvement of world health status. A first group of CE Success Stories was captured, 150 from 90 countries—from the prior 10 years and presented to health leaders at the WHO World Health Assembly in 2016. In 2017, another 250 with a total of 125 countries were added from 2016–2017 presentations.

Yadin David, Tom Judd

Bed Management in Hospital Systems

The paper presents a design for a bed management web-application to efficiently provide for the allocation of beds inside hospitals to reduce the diversions (transfer of patient in other ward or hospital) and thus the number of outliers (patient admitted in not-right ward) which may cause a longer length of stay. Information system helps the role of Bed Manager to improve the performances of the hospital-care flow optimizing the clinical paths. The system itself analyzes the interaction between patients, admission status and personnel in order to reduce the length of stay and the cost of care for hospitals. The application is designed to be linked to an existing facility manager system to gather information about the number of beds and their physical location in each room.

E. Iadanza, A. Luschi, A. Ancora

Navigation Algorithm for the Evacuation of Hospitalized Patients

The paper presents a model to support evacuation plans design for fire emergency management in healthcare facilities. It relies on existing path analysis algorithms such as Dijkstra and fire propagation simulation, also evaluating the level of criticality typical of healthcare facilities such as patients’ speed based upon their illness and admission and architectural structure of wards. The algorithm automatically evaluates the safest evacuation path (which may not coincide with the shortest) for single typology of patient (ambulating, partially-ambulating, completely non-ambulating, auto-sufficient or not) and inpatient unit (ICU, ordinary ward, short-observation unit) in relation to the position of the fire trigger. The results of the algorithm are shown by using SVG-rendered graphic of existing hospital’s layout.

E. Iadanza, A. Luschi, T. Merli, F. Terzaghi

A Decision Support System for Chronic Obstructive Pulmonary Disease (COPD)

Obstructive chronic obstructive pulmonary disease (COPD) is a respiratory disease characterized by a chronic air flow limitation and associated with major economic and social problems. In an attempt to find a solution to these problems, numerous systems of clinical decision support for the management of patients with COPD have been developed in recent years. In particular, systems based on machine learning algorithms have been developed with the aim of monitoring the health status of patients and foreseeing and preventing exacerbations and hospital admissions. An in-depth research into scientific literature has shown that, in the state of the art, these goals have not yet been met and the performance of the current systems is not clinically acceptable. The aim of this work is the design and implementation of a new clinical decision support system that can at least partially fill the gaps present. The first step in the work was to try to replicate the performance of support systems for similar decisions, already present in scientific literature. Using the physiological parameters acquired by 414 patients using respiratory function tests, two predictive models were made using the same machine learning algorithms (neural network and support vector machine). The performance obtained was comparable to those of the scientific literature. The next step was to create a new predictive model, with superior performance to previous models. The machine learning algorithm chosen is C5.0. The performance obtained was significantly better than the two previous models. The new predictive model was implemented within a user interface, implemented in Java programming language, the COPD Management Tool. The software developed allows the evaluation and classification of the results of respiratory performance tests, with excellent performance, compared to the current state of the art and can therefore be used in many clinical applications.

Ernesto Iadanza, Vlad Antoniu Mudura

Virtual Course for the Americas: Healthcare Technology Planning and Management Over the Life Cycle

Clinical engineers are well suited as healthcare technology planning and management leaders working with stakeholders from clinical, administrative and other healthcare professions. However, education and training in this topic for healthcare professionals is limited outside the high income, developed countries. To provide accessible training and education to the low and middle income countries, a 100% virtual course, Healthcare Technology Planning and Management, was developed by the Technical Services Partnership—University of Vermont USA, a WHO Collaborating Center for Health Technology Management, to teach students on best practices to follow over the healthcare technology life cycle: assessment, replacement, budgeting, acquisition, deployment, training, patient safety, compliance and maintenance. The global state of medical devices, information systems and the convergence of technologies is part of the learning along with the setup and operation of a clinical engineering department in a healthcare system. The Healthcare Technology Planning and Management bi-lingual course was first taught on the Pan American Health Organization Virtual Campus for Public Health in 2015 to participants from the Caribbean and Latin America countries. The course was conducted a second time over a 15-week period in 2017. Overall, 96 students have successfully completed the course. The course showed significant interaction and engagement by participants in discussion boards and forums. For the next course session, it is hoped that the course will be translated to Portuguese with adaptation to Brazil to allow a three language offering. Also live workshops focused on solving real life healthcare technology challenges in the Americas are planned.

Tobey Clark, Alexandre Lemgruber, Rossana Rivas, Francisco Caccavo, Tatiana Molina Velasquez, Javier Comacho

Model HTM Application in Failure Analysis for Air Compressors in the Dental Service of Primary Health Care

This study presents a failure cause analysis in medical air compressors in dental services of primary health care in Santa Catarina, Brazil. The study classifies failures, from 2007 to 2016, associated with the three domains of the methodology developed for HTM: Human Resources (DHR), Infrastructure (DI) and Technology (DT). From these failures, 58% were associated to DT, 31% to the HRD and 11% to the DI. Data collection was from the HTM Information System of the IEB-UFSC CE and the application of HFMEA. This analysis identifies which failures are related to wear of parts due to their life cycle in DT. In the DI, the causes were the lack of electrical protection and inadequate electrical wirings with manufacturers and technical standards. In DHR, the lack of a manual purge procedure is a cause of failure. As a result, a checklist for functional equipment verification was implemented during the CE technical inspection, which identifies fault conditions and associated domains. For DT, a preventive maintenance program was implemented to replace oil and shorter its service life. In order to reduce the failures associated to the DI, adjustments were made in the compressor shelters with installation of electrical protection and resizing of the electrical system. For the failures associated with the DHR, didactic materials were developed for training with a proposal to improve operational routine, best practices and an installation program of automatic purger in units of greater demand for dental service. The results of these actions led to a reduction in the occurrence of failures and validated the application of HTM model developed for Primary Health Care is important contribution for add quality to primary health care system.

Priscila Avelar, Renato Garcia

Support in the Medical Equipment Incorporation Decision: Hyperbaric Oxygen Therapy Adjunct for Diabetic Foot Ulcers Therapy

This paper presents a study to assist of a Decision Support Systems and Clinical Engineering Health Technology Management. The methodology is based on methodological guideline for the evaluation of medical equipment addressing its main domains (Clinical, Admissibility, Technical, Operational and Economic) in order to verify the incorporation of Hyperbaric Chambers in comparison to the outsourcing service for the injuries treatment diabetes carriers in Santa Catarina, Brazil. The HBOT application is still very controversial, often generating doubts and making it difficult to make decisions about its incorporation for the public health services. As a result, the Systematic Review, Randomized Controlled Trials and clinical reports were selected in the clinical domain and the operational and technical domain, it is performed a comparative of equipment with its technological resources and service, seeking to analyze parameters that influence in its performance. In the economic domain, through the total cost of ownership, it was estimated it’s direct and indirect costs related to the equipment’s acquisition and inherent to the life cycle sustainability. HTA for medical equipment present several barriers due to the lack of evidence and quality information, it is expected that this work can generate scientific evidences of knowledge and instruments to enable new research involving hyperbaric chambers, as well as contribute to decision-making or other concomitant programs, due to the application of resources in a planned and adequate decision.

Flávio Mauricio Garcia Pezzolla, Priscila Avelar, Jonas Maciel, Renato Garcia

Augmented Reality Technology as a Tool for Better Usability of Medical Equipment

The use of medical equipment may be compromised by the lack of knowledge of users about important information and operational characteristics that may cause adverse events. Clinical engineering has as an important function to guide and qualify users in adapting to the use of technology to obtain safer and more reliable health technology processes. The new augmented reality tools, whose main objective is to overlap virtual information in reality through technology, are a good alternative to develop solutions focused on the orientation and qualification of users. This paper presents a proposal to develop a platform for support in the orientation and teaching of medical device users. With this augmented reality platform, through the use of mobile devices, the user can access in real-time information on procedures of adjustments, characteristics, ways of use and control of the medical equipment. This prototype developed for the pulmonary ventilator uses augmented reality in order to enhance its interactions with computer applications more naturally, it seeks to present information about the different ventilation modes, equipment initialization procedures and interactive contents to the user through links and videos. Modern pulmonary ventilators present challenges to users due to the need of knowledge, such as configurations and ways of using parameters; the patient’s trigger in the assisted ventilation mode; use of assisted aspiration; pressure alarm setting. These actions are not usually carried out adequately generating possible adverse events, being this situation one of the main objectives of the use of the technology in the platform for the user support. The preliminary results obtained in this prototype characterize this solution as a support tool for activities developed by Clinical Engineering to improve processes in health care.

Jonatas Magno Tavares Ribeiro, Juliano Martins, Renato Garcia

Hospitals With and Without Clinical Engineering Department: Comparative Analysis

In Buenos Aires province, first and second levels are provided by City government, whereas third and fourth levels are provided by 77 provincial Hospitals. The Public System is free of charge for all citizens. In these hospitals technical support of medical devices, preventive and corrective maintenance, has been and is carried out by the vendors´ technical services (manufacturers and distributors), or by companies that are dedicated to the technical service of medical equipment. These services do not include the permanent presence of technicians or engineers in the hospital. There is an exception to the procedure mentioned in 18 hospitals, which, by means of an agreement between the MoH and the National Technological University, have implemented clinical engineering departments. The department activities are carried out by graduates and undergraduate students, who perform tasks within the Hospital every weekday in an office assigned for that purpose, and with the support of the University structure. The object of this work is to establish qualitative and quantitative differences between two hospitals with the same characteristics of health services, one with department of clinical engineering and the other with contracted services, both with the modalities explained. For this purpose there were measurements of the time that medical devices have been out of use for damage, repair costs, customer satisfaction surveys of users, administration personnel and management.

Marcelo Horacio Lencina, Sergio Damián Ponce, Débora Rubio, Bruno Padulo, Gustavo Ariel Schuemer

Evaluation of Downtime of Linear Accelerators Installed at Radiotherapy Departments in the Czech Republic

The National Radiation Protection Institute (NRPI) performed the study evaluating linear accelerator (linac) unscheduled downtime and other parameters related to linac failure (e.g. treatment cancellations, patients transferred to other linac, patients treated with modified dose fractionation) at radiotherapy departments in the Czech Republic. Thirteen radiotherapy departments with at least one linac (out of 21 departments in the Czech Republic) voluntarily participated in the study covering 29 out of 47 linacs. Downtime was evaluated for a one year period from July of 2016 to June of 2017. The methodology was as follows: NRPI designed the data entry form which was sent electronically to medical physicists at participating radiotherapy departments. Data related to linac failures were filled in. The completed forms were evaluated by NRPI. Unscheduled downtime was defined as time when linac cannot be operated during operating hours. Unscheduled downtime per linac per year ranged from 4 to 222 h (mean = 73 h, median = 61 h). Downtime percentage calculated as a ratio of downtime and total sum of operating hours per year ranged from 0.2 to 7.6% (mean = 2.8%, median = 2.2%). The number of treatment cancellations per linac per year ranged from 0 to 661. Unified methodology enabled objective comparison of linac downtime at particular radiotherapy departments in the Czech Republic. The study confirmed usefulness of having minimally two matched linacs at a department. The results of this study could help radiotherapy departments negotiate better service contract (e.g. agreement on maximum guaranteed downtime).

Vladimir Dufek, Ivana Horakova

Application of Engineering Concepts in the Sterile Processing Department

This study has been performed in the Sterile Processing Department (SPD) at Women’s Hospital “Professor Doctor José Aristodemo Pinotti in the State University of Campinas. The objective of this study is to evidence the importance of using engineering concepts to manage the processes of Sterile Processing Department. By applying the value stream mapping in the SPD it was possible to identify some problems in the process such as bottlenecks and nonconformities according to the Brazilian current sanitary legislation. Engineering tools were applied to understand how the processes were performed at CAISM. Measurements were collected from specific steps throughout the process to measure the cycle time of each step and then calculating the process lead time, the process cycle efficiency and the percentage of non-value-added time. The PDCA was also applied in order to implement and monitor the changes. Additionally, new methods and culture have been adopted to create a more collaborative, efficient and engaging environment.

Hermini Alexandre Henrique, Borges Ana Carolina, Longo Priscilla

The Application of the Total Cost of Ownership Approach to Medical Equipment—Case Study in the Czech Republic

Czech hospitals purchase the most expensive medical technology using public procurement process and they often make their purchasing decisions based on the lowest bid price. However, the management of hospital in most cases is unaware that the purchase price is only a minor part of the total cost of ownership of the equipment. This study intended to assess the nature of the Total Cost of Ownership (TCO) method in applications to medical equipment in the Czech Republic, and to carry out TCO analysis for selected medical equipment units. In order to evaluate the awareness and utilization of TCO in Czech hospitals, a quantitative research method (questionnaire) was used. The questions were addressed to the investment departments of the hospitals. To accomplish the research objectives, a TCO analysis for selected medical devices (X-ray machine, SPECT/CT and ultrasound scanner) was conducted. For each piece of equipment, four cost items were considered: acquisition cost; maintenance cost; operational cost and the cost of disposal. The results of questionnaire survey demonstrate that the TCO method was unknown to most of the respondents (67%) and the respondents usually make decisions based on the purchase price of medical equipment. All respondents who have already used the TCO method indicated that this method was useful to them. The results of the case study imply that the operating cost for the selected devices over five years are comparable to the purchase price. SPECT/CT scanner was the only one unit, where the acquisition cost was higher than the operational. In case of purchase of expensive medical technology, health care facilities often make decisions on the basis of the lowest bid price. According to the calculated TCO, this parameter is not the only important cost driver in the life cycle of medical equipment in hospital.

Petra Hospodková, Aneta Vochyánová

The Profile of Clinical Engineering in Espirito Santo, Brazil

As a result of high rates of non-operating equipment due to the lack of maintenance and proper training, Clinical Engineering has been growing considerably in Brazil since the 1990s and, therefore, its demand. In the State of Espírito Santo (ES), the reality is different from found in large cities. Because of that, this article has the following purposes: to verify the presence of Clinical Engineers in ES; to analyze the team composition and the presence of predictive and preventive maintenance procedures; and to compare the proportion of CT and MRI equipment in ES with national and international data. For this, data gathering of 97 hospitals registered in the National Registry of Health Establishments was carried out to obtain a list of existing equipment in the places and the way that maintenance service of such equipment is performed, as well as the composition of the team. The results obtained shows most of the general hospitals have outsourced Equipment Maintenance Service and those responsible for Clinical Engineering do not have specialization in the area or a degree in engineering. In addition, there are 0.75 MRI equipment and 0.50 CT for each 500 thousand and 100 thousand inhabitants, respectively, in the Universal Healthcare Service, values below determined by ordinance MS 1101. Thus, these data corroborate the need of increasing the supply and training of professionals in Biomedical Engineering and Clinical Engineering areas to promote additional study in the technological management practices of such equipment.

L. A. Silva, F. L. Cunha, K. L. Oliveira

Reduced Cost Training Program in Minimally Invasive Surgery

Minimally Invasive Surgery (MIS) procedures are now considered mainstay practice in the best hospitals wordwide. Despite its benefits, high costs and increased hazards appear as disadvantages for this technology. Suboptimal surgeon performance is a major hazard in many centers and can be overcome by an adequate training program. This work describes a reduced cost Training Program (TP) composed of three levels of theory and practice activities to improve the skills of the surgeons in MIS. The basic level is composed by 1 h of lessons on the videosurgery setup, optics and instruments, and a practice lessons composed of eight exercises in inanimate models. The intermediary level consists of 1 h of theory with 6 h of practice exercises in electrosurgery (chicken leg) and 4 h of laparoscopic suture in Neoderma simulation pieces. The third (advanced) level, consists of a hysterectomy in a living animal (pig). The investment in permanent assets for the basic and intermediary levels is roughly US$ 12,000,00; and for the advanced level, US$ 180,00 are needed per procedure. This TP has been applied in a multidisciplinary program involving medicine and clinical engineering areas in a University Woman´s Hospital. Twenty-one medical residents started the program and 10 completed all levels.

A. H. Hermini, I. M. U. Monteiro, L. O. Z. Sarian, J. C. C. Torres

Evaluation of Benefit of Low Dose CT in the Diagnosis of Charcot Arthropathy

Diabetes mellitus (DM) is accompanied by many complications (nephropathy, neuropathy, ischemic heart disease etc.), while the foot ulcer falls among the most serious ones. The main problem for the right diagnosis of this syndrome is an appropriate choice of a diagnostic scenario. The aim of this study is to analyse the current possibilities of DM diagnostics using particular imaging modalities, and to compare them with a three-phase skeletal scintigraphy complemented by a low-dose CT. The principal method of this work was the cost effectiveness (C/E) analysis of individual diagnostic modalities in relation to a timely detection of the disease completed by a sensitivity analysis. The result of a multiple-criteria decision analysis calculated by means of the TOPSIS method was used as the effect for the C/E calculation. Nine basic criteria entered the analysis. The values of the final effects of individual modalities are in favour of the skeletal scintigraphy and the leucoscan plus the low-dose CT. Furthermore, total costs were calculated for individual diagnostic approaches from the perspectives of a medical facility and of a health insurance company. In both cases, the lowest costs were reached for the magnetic resonance, which has also significantly influenced the final value of the cost effectiveness. In the sensitivity analysis, variations in the skeletal scintigraphy and/or leukoscan sensitivity did not affect the final order of the diagnostic modalities provided unchanged weights of the criteria. The same conclusion was also in the case of the magnetic resonance. A change in the order was detected for the skeletal scintigraphy with the low-dose CT and for the leukoscan in the case of a decrease in specificity by 40 or more percent. The study opens a topical issue and forms a basis for a broader discussion concerning Charcot osteoarthropathy diagnostics within the professional community.

Markéta Štveráková, Michaela Steklá, Miroslav Selčan, Petra Hospodková

Development of Methodology of Evaluation for Medical Equipment Replacement for Developing Countries

Currently, decision-making in hospitals and health institutions in developing countries about the replacement or withdrawal of medical equipment mainly involves a series of subjective positions about the time at which these actions should be carried out. It is for the foregoing that not always have the technical, clinical or economic basis on the request for the withdrawal of any equipment. There are several quantitative methodologies in the world that evaluate a considerable amount of parameters about the equipment and with this determine the status in which it is, however, these methodologies are difficult to apply especially in the public healthcare system of countries in development due to the ranges of evaluation of the parameters are focused on countries that acquire the technology as it goes to market, or even are technology manufacturing countries. It is due to the above that in this project a methodology is designed to evaluate medical equipment so that it can be used in countries that do not have the degree of substitution of developed countries. It is hoped that with this methodology it will be possible to anticipate equipment obsolescence and make the corresponding substitution at the best time according to the possibilities of each institution, based on quantitative data. The methodology is based on the evaluation of eight parameters that include the technical, economic and clinical part of each equipment.

Mario Andrés Alvarado, Sandra Luz Rocha

Toward a Novel Medical Device Based on Chromatic Pupillometry for Screening and Monitoring of Inherited Ocular Disease: A Pilot Study

Chromatic pupillometry is a relatively novel research tool for retinal function evaluation and may be an appropriate and easier way to diagnose and monitor inherited retinal diseases in paediatric population. Nevertheless, although the method is clinically feasible in paediatric populations, as shown by several non-ocular studies, only few studies, on a small size sample of paediatric subjects, are available. To the best of the authors’ knowledge, no medical device based on chromatic pupillometry was CE-marked for diagnosis and/or monitoring of these conditions. Therefore, we designed a pilot study in order to evaluate clinical feasibility, reliability and utility of chromatic pupillometry. The study sample consists of sixty patients, affected by inherited ocular diseases. A pupillometric system, including definition of pupillometric protocols, have been set up. In the current paper, we present the comparison between the measurements obtained in one patient affected by Retinitis Pigmentosa and a healthy age-matched control in order to disclose differences in chromatic pupillometry parameters between case and control.

Paolo Melillo, Antonella de Benedictis, Edoardo Villani, Maria Concetta Ferraro, Ernesto Iadanza, Monica Gherardelli, Francesco Testa, Sandro Banfi, Paolo Nucci, Francesca Simonelli

Design Model for Risk Assessment for Home-Care Lung Ventilation

Introduction: The study consists of two objectives. The first objective is to assess the risks associated with the whole process of treatment using home-care lung ventilation (HLV). The main source for describing such risks were foreign studies. The other objective is to compare risk assessment methods based on the current situation in the Czech Republic and in the world. Methods: The selected methods—Failure Mode and Effects Analysis (FMEA), Health Failure Mode and Effects Analysis (HFMEA), Fault Tree Analysis (FTA) and Root Cause Analysis (RCA)—were compared using comparative analysis, and subsequently examined, in the specific area of home-care lung ventilation. Results: The final objective is to design a model for risk assessment in the field of home mechanical ventilation based on the existing knowledge. This model includes both a prospective and a retrospective analysis. Their appropriateness of use is documented in this paper; according to their specificities they are used in a variety of areas. Discussion: Implementation of risk analyses in this area can contribute to increasing the safety and quality of provided care, and at the same time help attract more support to the home-care lung ventilation program.

Ivana Kubátová, Martin Chlouba, Ondřej Gajdoš

Rapid Manufacturing and Virtual Prototyping of Pre-surgery Aids

Progressive development of rapid manufacturing and virtual prototyping have a significant influence not only in the industry and transport, but also in the medicine. Presurgical support and preparation of a surgeon with use of these technologies, especially in complex cases, can help prepare more precise plan of surgery and perform a simulated operation. The aim of these studies was to develop a methodology and manufacture an anatomical model of a kidney with a tumour, using rapid manufacturing technologies and virtual prototyping techniques. The model was a part of a presurgical support, allowing a doctor to become acquainted with an organ and a tumour and was also used for a simulative operation of partial nephrectomy. Due to the fact that model has two functions (preoperative planning and simulative operation), an important part during the production process was to consult procedures like cutting or suturing. Combination between technology of 3D printing and vacuum casting and silicon usage allowed to create a model, which imitates living tissues, especially the renal cortex and tumour. Transparency, which is a property of both models—physical and virtual—also plays a relevant role. Transparency helps surgeons in precise planning before operation. Doctors can familiarize themselves with arrangement of internal structures and pathologically altered areas. The collected information and tests performed with a cooperating hospital helped evaluation of created models, their usefulness and future implementation possibilities.

Magdalena Żukowska, Filip Górski, Gabriel Bromiński

Radiation Oncology Physics and Systems

Frontmatter

Cobalt-60 Radiotherapy Units, Assessment of the Utilization or Disinvestment in Latin America

Objectives: To assess whether the criteria for disinvestment in health technologies—clinical, technological advantage, safety, lifecycle, human factor and costs—are applicable for the withdrawal of cobalt-60 radiotherapy units (Co-60 RTUs) in Latin America, considering health outcomes, and that the economic context, replacing this technology with linear accelerators (LINACs) is not always feasible. Methods: A systematic review of articles published between 2003 and 2017 in PubMed, Cochrane Library and CRD on the current use of Co-60 RTUs and publications comparing them with LINACs has been made. With a manual search of the references of selected articles. Results: The clinical results indicate that Co-60 RTUs have a significant role in treatment of patients with tumors of head, neck, breast and some types of superficial soft tissue sarcomas of the extremities. The comparison between Co-60 RTUs and LINACs results in advantages for linear accelerators in: the variety of cancer type that can be treated, the delivery of treatment, lifecycle and safety. In terms of acquisition costs, although Co-60 RTUs are comparable to a low-energy LINACs. Considering the number of existing Co-60 RTUs in Latin America, their effectivity and safety in the treatment of some types of cancer and the shortage of skilled professionals, its use can still be beneficial. Conclusions: Whereas in Latin America more than 26% of radiotherapy equipment are Co-60 RTUs, available economic resources and staff are limited. A recommendation is to continue utilizing such equipment in some types of cancer where they can be used: head, neck, breast and superficial sarcomas extremity soft tissue and allocate the use of existing LINACs for other types of cancer and in special cases like pediatric patients.

Daniel Martínez Aguilar, Alejandra Prieto-de la Rosa, Esteban Hernández San Román, Arturo Becerril Vilchis, Francisco Ramos Gómez, Alessia Cabrera Yudiche

Incorporating the Local Biological Effect of Dose Per Fraction in IMRT Inverse Optimization

In intensity modulated radiation therapy (IMRT), the dose in each voxel of the organs at risk (OAR) can be strongly reduced compared to conformal radiation therapy (RT). Due to the sensitivity of late side-effects to fraction size, a smaller dose per fraction in the normal tissues represent an increased tolerance to RT. This expected reduction in biological effect may then be used as an additional degree of freedom during IMRT optimization. In this study, the comparison between plans optimized with and without a voxel-based fractionation correction was made. Four patients diagnosed with a head and neck (HN), a breast, a lung or a prostate tumor were used as test cases. Voxel-based fractionation corrections were incorporated into the optimization algorithm by converting the dose in each normal tissue voxel to EQD2 (equivalent dose delivered at 2 Gy per fraction). The maximum gain in the probability of tumor control (PB), due to the incorporation of the correction for fractionation in each voxel, was 1.3% with a 0.1% increase in the probability of complications (PI) for the HN tumor case. However, in plan optimization and evaluation, when tolerance doses were compared with the respective planned EQD2 (calculated from the 3-dimensional dose distribution), PB increased by 19.3% in the HN, 12.5% in the lung, 6.2% in the breast and 2.7% in the prostate tumor case, respectively. The corresponding increases in PI were 2.3%, 6.2%, 1.0% and 0.7%, respectively. Incorporating voxel-based fractionation corrections in plan optimization is important to be able to show the clinical quality of a given plan against established tolerance constraints. To properly compare different plans, their dose distributions should be converted to a common fractionation scheme (e.g. 2 Gy per fraction) for which the doses have been associated with clinical outcomes.

Brígida da Costa Ferreira, Panayiotis Mavroidis, Joana Dias, Humberto Rocha

Accurately Evaluating Settling Responses of Ionization Chambers Used in Radiation Therapy Depend on the Accelerating Tube

The growing use of multiple small fields in radiotherapy treatments such as intensity-modulated radiation therapy has increased the importance of small-field dosimetry. In this study, we investigate the settling response of a set of ionization chambers exposed to 4, 6, and 10 MV stereotactic radiotherapy X-ray fields. Previous studies had reported that lack of pre-irradiation could result in settling response errors of up to several percentage points. While the use of ionization chambers does contribute to this behaviour, the most obvious factors affecting the settling response appear to be the area of the insulator, the material used for the central collector electrode, and the accelerating tube. The results of this study show that Farmer-style ionization chambers with electrode connections that are guarded up to an active air volume settle quickly (within five minutes); moreover, the changes in their responses are small. On the other hand, small ionization chambers exhibit settling times of 11–24 min. In this study, the settling times of small ionization chambers were found to be dependent on the accelerating tube.

Tetsunori Shimono, Yasuyuki Kawaji, Tatsuhiro Gotanda, Rumi Gotanda, Hiroshi Okuda

Monte Carlo Dosimetry of Organ Doses from a Sweeping-Beam Total Body Irradiation Technique: Feasibility and First Results

Total body irradiation (TBI) is a radiation treatment often purposed to suppress the immune system prior to a bone marrow transplant. Several toxicities can arise in TBI, and high-quality dose volume data for organs at risk are required if one is considering any change from a well-established technique. We present a novel Monte Carlo (MC) dosimetry technique to acquire this data based on our current TBI technique that accounts for a sweeping-beam Cobalt-60 delivery, a stationary flattening filter, patient-specific lung compensators, and two patient treatment positions. For each patient, a virtual MC phantom is created including the planning CT image in each treatment position (supine and prone). The results from dose simulations on each phantom were summed together geometrically with a deformable registration tool. Dose volume statistics for lungs, liver, thyroid, and kidneys are obtained. The preliminary results of a retrospective study using this technique on patients who have received TBI at our clinic indicate that, for a total body prescription dose of 12 Gy ± 10%, the mean body dose ranged from 11.19 to 12.15 Gy with smaller patients receiving lower mean body doses than larger patients. The mean dose delivered to the thyroid was the highest of the contoured organs receiving up to 12.84 Gy, and the lung doses were the most heterogeneous, with standard deviations up to 0.73 Gy in individual patients. This high-quality dose data shows promise for use in both routine quality assurance of our current technique, and to provide baseline data for development of a new technique. The technique could also be adapted to TBI techniques at other clinics that include compensators, flattening filters, moving beams, and/or multiple treatment positions.

Levi Burns, Tony Teke, I. Antoniu Popescu, Cheryl Duzenli

Rapid Prototyping, Design and Early Testing of a Novel Device for Supine Positioning of Large Volume or Pendulous Breasts in Radiotherapy

Here we describe the development of a novel device for breast positioning in supine radiotherapy that reduces breast sag and skin folds for patients with large or pendulous breasts. The overall aim of this work is to provide a practical and robust means of reducing high grade skin toxicity (moist desquamation) which tends to occur in skin folds. Participants with breast cup size D or greater were recruited to this ethics board approved prototype design study. Brassiere size, cup size, breast diameter, body mass index, height, weight, skin folds and torso dimensions were measured. Participants were positioned in treatment position on a breast board, with arms above the head and skin folds were identified and measured. 3D optical surface imaging provided initial design ideas and a rapid prototyping process using 3D printing was employed to arrive at a suitable design. The final clinical device consists of a curved carbon fibre breast support scoop suspended from a rigid frame that is compatible with commercially available breast boards. In addition to reducing skin folds, the device better positions the breast on the chest wall to help minimize the volume of normal tissue being irradiated and facilitates rapid setup. We present results of preliminary testing of the device, including dose buildup incurred by the carbon fibre scoop, skin fold reduction data and treatment planning data from CT simulations with and without the device. Surface dose with the device in place remains less than 80% of the prescription dose to the breast. Skin folds were reduced and reductions in irradiated volumes of lung and body were achieved compared with clinical plans without the supportive device. The novel breast support shows great potential to address a long-standing problem for a significant population of patients undergoing radiotherapy for breast cancer.

Levi Burns, Scott Young, Joel Beaudry, Bradford Gill, Robin Coope, Cheryl Duzenli

Radiotherapy Quality Assurance Using Statistical Process Control

Statistical process control (SPC) is an analytical decision-making tool that employs statistics to measure and monitor a system process. The fundamental concept of SPC is to compare current statistics in a process with its previous corresponding statistic for a given period. Using SPC, a control chart is obtained to identify random and systematic variations based on the mean of the process and trends are observed to see how data can vary in each evaluated period. An upper and lower control limit in an SPC derived control chart indicate the range of the process calculated based on the standard deviations from the mean, thereby points that are outside these limits indicate the process to be out of control. Metrics such as: process capability and acceptability ratios were employed to assess whether an applied tolerance is applicable to the existing process. SPC has been applied in this study to assess and recommend quality assurance tolerances in the radiotherapy practice for helical tomotherapy. Various machine parameters such as beam output, energy, couch travel as well as treatment planning parameters such as minimum percentage of open multileaf collimators (MLC) during treatment, planned pitch (couch travel per gantry rotation) and modulation factor (beam intensity) were verified against their delivery quality assurance tolerances to produce SPC based tolerances. Results obtained were an indication of the current processes and mechanical capabilities in the department rather than a vendor recommended or a prescriptive approach based on machine technicalities. In this study, we have provided a simple yet effective method and analysis results to recommend tolerances for a radiotherapy practice. This can help improve treatment efficiency and reduce inaccuracies in dose delivery using an assessment tool that can identify systematic and random variations in a process and hence avoid potential hazardous outcomes.

Diana Binny, Craig M. Lancaster, Tanya Kairn, Jamie V. Trapp, Scott B. Crowe

Stereotactic Radiosurgery for Multiple Brain Metastases: A Dose-Volume Study

A substantial number of cancer patients develop brain metastases, which often present as multiple lesions. Stereotactic radiosurgery (SRS) can be used to treat brain metastases, with some incidental dose to the healthy brain. This study evaluated the effect of the number and combined volume of metastatic lesions on the dosimetric quality and the deliverability of a small sample of SRS test treatments. Five simulated static conformal arc treatments of 4–12 brain metastases were planned for linac-based multi-isocentre delivery to a head phantom. Film measurements were used to verify dose calculation and treatment delivery accuracy. Several of the treatment plans were considered clinically acceptable when local dose prescriptions (14–18 Gy) were used, but when the prescription dose to all metastases was increased to match the RTOG 0320 recommended value of 24 Gy, no plans resulted in a V12 less than 10 cm3. Agreement between planned and measured dose was poorest for the treatments of 10 and 12 metastases, due to increased disagreement in out-of-field regions. Using the multi-isocentre static conformal arc method, it is possible to deliver treatments to relatively large numbers (at least 12) and total volumes (at least 8 cm3) of brain metastases without excessive radiation doses being delivered to the healthy brain, provided that reduced prescription doses are acceptable.

Tanya Kairn, Somayeh Zolfaghari, Daniel Papworth, Mark West, David Schlect, Scott Crowe

Retrospective Audit of Patient Specific Quality Assurance Results Obtained Using Helical Diode Arrays

A retrospective audit was performed for existing patient specific quality assurance (PSQA) results measured on two ArcCheck helical diode arrays (Sun Nuclear Corporation). Twenty-five volumetric modulated arc therapy (VMAT) and thirty-two helical tomotherapy (HT) treatment plans were re-analysed using SNC patient software (version 6.2) and in-house gamma analysis code (developed in Python). Global gamma analyses were performed on the measured and calculated data (2%/2 mm) to identify the registration shift which provided the greatest gamma agreement index (GAI). Audit results indicated that when the ArcCheck devices were used for VMAT and HT, 1 mm longitudinal (Y) registration shifts frequently provided better GAI results than no shift. Specifically, the SNC and Python codes both identified a significant trend for longitudinal shifts for both ArcCheck devices. No significant trend was observed for roll (X) registration shifts. Measurements performed with physical shifts of the ArcCheck device improved the GAI results with no shift applied, suggesting that unless there is a co-incidental offset in the position of the radiation isocentre on both the TomoTherapy unit and the linac, there may be an actual displacement of the centre of the diode array and the marking lines on the two ArcCheck devices. This behaviour is dependent on gamma evaluation criteria used. The results of this study confirm the necessity of undertaking regular audits of QA results, as well as the need to consider sources of geometric uncertainty when selecting gamma evaluation criteria and when applying automatic geometric shifts to measured data.

Liting Yu, Tanya Kairn, Scott B. Crowe

Optimising a Radiotherapy Optical Surface Monitoring System to Account for the Effects of Patient Skin Contour and Skin Colour

Optical surface monitoring systems (OSMSs) are designed to assist patient setup and patient motion management during radiotherapy treatments. Systems use projected and reflected patterns of coloured light on the patients surface and therefore depend on the skin’s optical absorbance and reflectance properties, which can vary with surface shape and colour. This study aimed to identify optimal operating parameters for the Catalyst HD OSMS (C-rad, Uppsala, Sweden) when used to monitor the surfaces of 3D-printed objects with various convex and concave surfaces, one of which was painted in six different colours with various levels of red and black saturation (from light pink to dark grey). The degree of surface detection was assessed via the Catalyst HD interface, with different levels of gain (100–600%) and signal integration time (1–7 ms). The OSMS was able to detect horizontal and convex shapes more consistently than vertical or steeply angled surfaces. The OSMS was not able to detect the darkest surface at all, even with the highest gain and the longest integration times. Mid-grey surfaces were detectable only when the integration time was increased to 2 s. All pink surfaces were easily detectable at the shortest integration time, with the OSMS performing best when red saturation was highest. Further work is recommended, as the red undertone of all human skin may lead to improved results for real patients. However, these preliminary results indicate that careful commissioning and optimisation of OSMS systems may be required before they can be used in radiotherapy treatments for a broad patient cohort.

Candice Milewski, Samuel Peet, Steven Sylvander, Scott Crowe, Tanya Kairn

Absolute Calibration of the Elekta Unity MR Linac Using the UK Code of Practice for High-Energy Photon Dosimetry

Absolute dosimetry for MR Linacs is complicated by non-standard reference conditions, the non-suitability of the UK secondary standard chamber for use in water and the effects of the magnetic field on the response of Farmer field chambers. Measurements were made on a pre-clinical 7 MV Elekta Unity MR Linac. Reference conditions were chosen as isocentre (143.5 cm SAD), 10 cm deep, 10 × 10 cm2 field and gantry angle 90° to avoid output variation from liquid helium levels dropping in the surrounding annulus. TPR 20/10 was measured as 0.698 at isocentre. Measurements on a conventional linac demonstrated that TPR 20/10 does not vary between SAD 100 cm and 143.5 cm. The UK National Physical Laboratory (NPL) provides calibration factors, ND, for the secondary standard NE 2611A thimble chamber in terms of absorbed dose to water. ND was taken for the value of the measured TPR 20/10. Independent intercomparisons were made at 6 MV on a conventional linac between the NE2611A and two PTW waterproof Farmer 30013 chambers. The response of these chambers varies very slowly with energy hence it is reasonable to assume this introduces minimal uncertainty. Ion recombination and polarity correction factors measured on the MR Linac were unchanged by the magnetic field. An additional correction factor to account for the 1.5 T magnetic field on the Farmer chambers was measured as 0.986 taking the ratio of TP corrected readings before and after ramp-up of the magnetic field. An orientation parallel to the magnetic field (along the bore of the MR Linac) was chosen to minimise the magnitude of this factor. An independent audit was performed by the NPL using alanine pellets and Farmer chambers calibrated via a water calorimeter from the Netherlands primary standards laboratory which operates within the MR Linac. This gave agreement with our calibration to within 1.0%.

G. Budgell, P. Gohil, J. Agnew, J. Berresford, I. Billas, S. Duane

Calibration Seed Sampling for Iodine-125 Prostate Brachytherapy

Use of iodine-125 seeds for intraoperative planning and delivery of low dose rate brachytherapy treatments for prostate cancer requires that the air kerma strength of the seeds be checked against the vendor-supplied calibration certificate at the beginning of the surgical procedure. In practise, activity checks of multiple sources are difficult to achieve in surgery. This study therefore investigated the reliability of a calibration method that sampled only one seed, or a small number of seeds, by evaluating the consistency the air kerma strengths of all seeds in three small batches of 10, 20 and 30 iodine-125 seeds and calculating the probability of achieving results representative of each batch, within different levels of uncertainty. For the cartridges containing 10, 20 and 30 seeds, the mean differences between the source strengths identified by physical measurement and their decay-corrected calibration certificate values were respectively $$ 5.0\% \pm 4.4\% $$, $$ - 2.7\% \pm 3.7\% $$, and $$ 0.4\% \pm 2.8\% $$. Assays of 5 randomly sampled seeds were shown to produce results within 3% of the mean air kerma strength of each batch, with larger assays producing less uncertainty. For these seeds, there was a greater than 30% chance that a randomly selected seed would have an activity that differed by more than 3% from the mean activity of all seeds in the cartridge. Although attractive as an efficiency measure, the testing of just one seed from a cartridge of iodine-125 seeds has a significant probability of producing an activity measurement that is not representative of the activity of the other seeds in the cartridge, potentially leading to substantial inaccuracies in implant dosimetry.

Scott Crowe, Tanya Kairn

Automated VMAT Treatment Planning for Complex Cancer Cases: A Feasibility Study

Treatment plans for high-risk prostate and endometrial cancer are highly complex due to large irregular-shaped pelvic target volumes, multiple dose prescription levels and several organs at risk (OARs) close to the targets. The quality of these plans is highly inter-planner dependent. We aimed to assess the performance of the Auto-Planning module present in the Pinnacle treatment planning system (version 16.0), comparing automatically generated plans (AP) with the historically clinically accepted manually-generated ones (MP). Twenty consecutive patients (10 for high-risk prostate and 10 for endometrial cancer) were re-planned with the Auto-Planning engine. Planning and optimization workflow was developed to automatically generate “dual-arc” VMAT plans with simultaneously integrated boost. Primary target (PTV1) included the prostate and seminal vesicles or the upper two thirds of vagina; PTV2 included the lymph-nodal drainage. PTVs were simultaneously irradiated over 25 daily fractions at 45 Gy for the PTV2 and 65/55 Gy to the prostate/endometrial PTV1. For AP plans, a progressive optimization algorithm is used to continually adjust initial targets/OARs objectives. Tuning structures and objectives are automatically added during optimization to increase the dose fall-off outside targets and improve the dose conformity. Various dose and dose-volume metrics, as well as conformity indexes and healthy-tissue integral dose were evaluated. A Wilcoxon paired-test was performed for plan comparison (p < 0.05 as statistical significance). All AP plans fulfilled the clinical dose criteria for OARs and PTV coverage. Dose coverage metrics for both PTVs were very similar with AP showing slight better results for PTV1. For both anatomical sites, differences in DVHs were no significant in overall dose range for rectum, bladder and small bowel. However, AP plans provided significant better conformity and an average decrease in Integral Dose of 6–10%. The Pinnacle Auto-Planning module is capable of efficiently generating highly consistent treatment plans, meeting our institutional clinical constraints.

Savino Cilla, Anna Ianiro, Gabriella Macchia, Alessio G. Morganti, Vincenzo Valentini, Francesco Deodato

Monte Carlo Validation of Output Factors Measurements in Stereotactic Radiosurgery with Cones

The purpose of this work is to assess 8 detectors variation performance for output factor (OF) determination, in a clinical 6 MV Varian Clinac 2100C stereotactic radiosurgery mode for cone irradiation using Monte Carlo simulation as reference. We study 10 cones with diameters between 30 and 4 mm. The evaluated detectors were ionization chambers: pinpoint and pinpoint 3D (PTW), diodes: SRS, P and E (PTW), Edge (Sun Nuclear), microdiamond (PTW) and EBT3 radiochromic films (Ashland). The OF were normalized with the 30 mm cone and compared to Monte Carlo (MC). For the 8 detectors, the OF measurements reproducibility was very high: r = 0.99 and p < 0.0001. The uncertainty of the MC calculation was lower than 0.8% (type A). The results show: pinpoints (axial position) underestimate OF until −2.3% for cone diameter ≥ 10 mm and down to −12% for smaller cones. Non-shielded (SRS and E) and shielded (P and Edge) diodes overestimate OF respectively up to 3.3% and 5.2% for cone diameter ≥ 10 mm but in both case >7% for smaller cones. Microdiamond slightly overestimates OF, 3.7% for all the cones and EBT3 film is the closest to MC with maximum difference ±1% whatever the cone size. Film is the more accurate detector for OF determination of stereotactic cones but it is restrictive to use. Pinpoints and diodes, respectively due to inappropriate size of sensitive volume and composition do not seem appropriate without corrective factors below 10 mm diameter cone. Microdiamond appears the best detector for all cones despite its sensitive volume size.

Nicolas Garnier, Régis Amblard, Rémy Villeneuve, Rodolphe Haykal, Cécile Ortholan, Philippe Colin, Joël Herault, Sarah Belhomme, Mourad Benabdesselam, Benjamin Serrano

Sensitivity of Electronic Portal Imaging Device (EPID) Based Transit Dosimetry to Detect Inter-fraction Patient Variations

The sensitivity of EPID-based transit dosimetry to detect patient variations between treatment fractions is examined using gamma analysis and a structural similarity (SSIM) index. EPID images were acquired for 3-dimensional conformal (3DCRT) and dynamic intensity modulated (dIMRT) radiation therapy fields in multiple fractions. Transit images were converted to doses, transit dose in the first fraction considered the reference dose. Variations in patient position or weight were then introduced in the subsequent fractions. Positional variations were examined using a lung and a head and neck phantoms. Anatomical variations were examined using a slab phantom in three scenarios, with solid water simulating tissue, medium-density fiberboard simulating fat, and Styrofoam simulating lung. The dose difference between the first and subsequent fractions was computed using various gamma criteria and the SSIM index. Using a criterion of 3%/3 mm, EPID can detect positional variations ≥ 4 mm, and tissue and fat variations ≥ 1 cm, whereas it cannot detect lung variations up to 4 cm. The sensitivity for 3DCRT is higher than for dIMRT. EPID can detect the most variations when using 3%/1 mm. With the SSIM index, EPID can detect a 2 mm positional variation and 1 cm of lung variation. The factor that optimized the sensitivity of EPID was a reduction in the distance to the agreement criteria. Our study introduces the SSIM as an alternative analysis with high sensitivity for minimal variations.

Omemh Bawazeer, Sivananthan Sarasanandarajah, Sisira Herath, Tomas Kron, Pradip Deb

A Study of Single-Isocenter for Three Intracranial Lesions with VMAT-Stereotactic Radiosurgery: Treatment Planning Techniques and Plan Quality Determination

Objective: To compare a modified single-isocenter technique between (1) 6 MV and 6FFF and (2) fixed collimator angles and adjusted collimator angles for three intracranial lesions by using VMAT-SRS. Materials and methods: Twenty patterns of three intracranial lesions varying in size and location were generated. The VMAT plans using Eclipse version 13.6 were initially generated according to the University of Alabama, Birmingham’s (UAB’s) guidelines. Planning parameters including 6 MV, 6FFF, and collimator angles were further modified. All plans were normalized to achieve a 99% dose coverage with 20 and 24 Gy to 5 mm and 10 mm lesions, respectively. Dosimetric parameters, including CIRTOG, CIPaddick, GI, HI, mean dose to the normal brain, and V5Gy and V12Gy, were analyzed using Wilcoxon or paired t-test. Results: The 6 MV plans with adjusted collimator angle provided better CIRTOG (1.217 vs. 1.266, p = 0.007) and CIPaddick (8.30 vs. 8.13, p = 0.007), while the 6FFF plans were not statistically different. For both energies, the adjusted collimator angles were less than V5Gy (p < 0.01), V12Gy (p < 0.01) and GI (p < 0.001) compared to the fixed collimator angles of UAB protocol, while the HI index was similar. The plans with 6FFF offered superior plan quality than 6 MV for target coverage (CIRTOG 1.222 vs. 1.266, p = 0.005 and CIPaddick 0.832 vs. 0.813, p = 0.002), dose fall off (GI 7.246 vs. 8.264, p < 0.001) and normal brain sparing (V12Gy 3.802 vs. 4.224, p < 0.001 and V5Gy 22.092 vs. 24.966, p < 0.001). Conclusion: The optimization of collimator angles show an improvement in dose fall-off and normal brain sparing relative to the fixed collimator angles. Plans with 6 FFF provide a better plan quality than 6 MV.

Wisawa Phongprapun, Janjira Petsuksiri, Puangpen Tangboonduangjit, Chumpot Kakanaporn

Evaluation of Time Delay and Fluoroscopic Dose in a New Real-Time Tumor-Tracking Radiotherapy System

A combined system comprising the LINIAC TrueBeam (Varian Medical Systems, Palo Alt, CA) and a new real-time tumor-tracking radiotherapy system, SyncTraX FX4® (Shimadzu Co., Kyoto, Japan), was installed in our institution. It consists of four pairs of an X-ray tube and a flat panel detector. The system was assessed on beam-on time delay between TrueBeam and SyncTraX FX4 and fluoroscopic dose during a real-time tracking. Delay time was measured by using a tumor-tracking radiotherapy phantom (CALIB PHANTOM ASSY, Shimadzu Co., Kyoto, Japan), in the cases of flattening filtered (FF) 6 MV photon beam, flattening filter-free (FFF) 6 MV photon beam, FF-10 MV photon beam, and FFF-10 MV photon beam with the LINAC TrueBeam. Half-value layer (HVL) in mm Al, effective kVp, and air-kerma rate during fluoroscopy were measured using a solid-state detector for the tube voltage (70–110 kV) and the current (50–100 mA). The LINAC delayed from the real-time tumor tracking system on beam-on by 140.9 ± 8.5, 119.8 ± 3.8, 126.1 ± 3.2 and 116.8 ± 9.7 ms for FF-6 MV, FFF-6 MV, FF-10 MV and FFF-10 MV, respectively. The HVL, effective kVp and air-kerma rates from X-ray tube #1 (X-ray tube #1 and #2 were embedded in the patient’s head side floor) were 4.98 ± 0.00 mm, 111.2 ± 0.1 kV and 9.14 ± 0.04 mGy/min for 110 kV X-ray at 100 mA. The HVL, effective kVp and air-kerma rates from X-ray tube #3 (X-ray tube #3 and #4 were embedded in the patient’s feet side floor), were 5.20 ± 0.00 mm, 110.0 ± 0.1 kV and 11.87 ± 0.06 mGy/min for 110 kV X-ray at 100 mA. These tube voltage and current are the maximum conditions of this study. The time delay of the real-time system is longer than the old system that used image intensifiers. The air-kerma rate from X-ray tube #3 was higher than that from X-ray tube #1.

Masayasu Kitagawa, Ayaka Hirosawa, Akihiro Takemura

Stereotactic Radiotherapy for Choroidal Melanoma: Analysis of Eye Movement During Treatment, Eye Simulator Design and Automated Monitoring System Development

Malignant choroidal melanoma is a choroidal tumor arising in the layer of blood vessels located beneath the retina. It is a rare occurrence, affecting five to every million inhabitants and rapidly evolving into metastasis. The stereotactic radiotherapy is one of the possible treatments for the disease, it consists in the application of small photon beams directed to the PTV, the prescribed dose is delivered in multiple sessions. The success of treatment depends directly, among others biomedical factors, on the precision of the application and how the treatment method can hold still the patient’s eye. This study aims: (a) to analyze the eye’s movement during the treatment for choroidal melanoma and the non-invasive method for fixating the patient’s eye; (b) to develop a monitoring software for patient eye gaze; (c) design a mechanical eye to verify the monitoring system. As a result, it is expected that the system will be improved, raising the precision and accuracy of application and reducing the damage to healthy tissues and side effects. After analyzing the positions of the iris center and calculating its displacements relative to the orthophoria point the standard deviation values of 0.368 mm and 0.364 mm were found for the X-axis and Y-axis, respectively. The LED lamp is enough for a noninvasive fixation of the patient’s eye during treatment. The mechanical eye now is able to verify the monitoring system software, as both work with resolutions within the limit given by the eye movement analyzes.

F. Souza, J. Valani, O. D. Gonçalves, D. V. S. Batista, S. C. Cardoso, D. D. Pereira

Configuration of Volumetric Arc Radiotherapy Simulations Using PRIMO Software: A Feasibility Study

Volumetric Modulated Arc Therapy (VMAT) uses non-uniform intensity fields allowing volumetric complex dose distributions. The simultaneous MultiLeaf Collimator (MLC) motion and Gantry rotation pose difficulties in the dose distribution calculation by Treatment Planning Systems (TPS). Furthermore, a dedicated Quality Assurance (QA) program and patient-specific dose verifications are requested. Monte Carlo dose calculation in Radiotherapy (RT) is a gold standard due to its most detailed description of radiation-matter interaction. Recently, the PRIMO software was proposed, providing several built-in RT units models, including TrueBeam. Nevertheless, VMAT is not implemented yet. In this work, TrueBeam was simulated in PRIMO using 6 and 10 MV in Flatness Filter Free (FFF) mode and at 15 MV with Flatness Filter inserted. The results were validated by Gamma Function (2%, 2 mm) based on reference measurements in water tank. The VMAT complex dynamic delivery is divided into a customizable number of probabilistically sampled static configurations of jaws, leaves and gantry angles. In-house algorithms were developed to interpolate the LINAC geometrical information along the process once the planned information is retrieved from the TPS output DICOM file. A Graphical User Interface (GUI) was developed to assist the user to configure PRIMO to simulate complex deliveries. Static simulations in reference conditions showed always >97% of Gamma points <1 for PDD and profiles at various depths and fields sizes for the 6, 10 and 15 MV primary beam respectively. The GUI properly read, manipulated and wrote the configuration data in a “ppj” format, which was accepted by PRIMO. The dynamic jaws, MLC and gantry motion were positively assessed by visual inspection of the static beam configuration in PRIMO. Dynamic irradiations were simulated and the gamma function tests against reference dose distributions showed good agreement with typical QA criteria. A GUI to configure PRIMO for VMAT irradiations allowed to enable a flexible workflow for simulating a general dynamic treatment.

Jorge Oliveira, Alessandro Esposito, João Santos

Evaluation of Deformable Image Registration Between High Dose Rate Brachytherapy and Intensity Modulated Radiation Therapy for Prostate Cancer

High risk prostate cancer is treated with a combination of intensity-modulated radiation therapy (IMRT) and high dose rate brachytherapy (HDR-BT). Deformable image registration (DIR) techniques used for dose accumulation sums dose distributions. The accuracy of DIR would get worse when density of an organ in a pair of registering two images differs greatly each other. Needles and contrast medium are used in HDR-BT. In this study, the effect of needles and contrast medium for DIR accuracy was evaluated. Six patients with prostate cancer were enrolled, who were treated with the combination of HDR-BT and IMRT. In the HDR-BT plan, needleless image (NI) and needleless and no-contrast medium image (NCI) were created from the original HDR-BT plan image (OI) to investigate the influence of needles and contrast medium. Both DIR and rigid registration (RR) were performed on the OI, NIs and NCIs by using MIM Maestro ver. 6.7.6 (MIM software Inc, Cleveland, USA) and after that the dose distribution of HDR-BT (used as the reference image) and IMRT were accumulated. The Dice Similarity coefficient (DSC) between DIR and RR were analyzed and compared each other. The mean DSC values of the prostate with DIR on OI, NI and NCI were 0.51, 0.57 and 0.73, respectively. The DSC with DIR on NCI was higher than DSC with DIR on OI and NI. The DSC values improved by removing the contrast medium.

Noriomi Yokoyama, Akihiro Takemura, Hironori Kojima, Kousuke Tsukamoto, Shinichi Ueda, Kimiya Noto

Intensity Modulated Radiotherapy (IMRT) Phantom Fabrication Using Fused Deposition Modeling (FDM) 3D Printing Technique

Design and fabrication of patient-specific radiotherapy phantom is now more accessible and cost-effective using 3D printing technology. This study fabricates a 3D printed radiotherapy phantom for quality assurance of Intensity Modulated Radiotherapy (IMRT). Using an IMRT Thorax anthropomorphic phantom (CIRS) as a substitute for an actual patient, a 3D printed radiotherapy phantom was designed based on a patient computed tomography (CT) scan during treatment planning. Before printing the phantom, the tissue equivalence of Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA) polymers used in 3D printing was characterized by quantifying its CT number and relative electron density to water. In the 3D printed phantom fabricated, it was shown that soft tissue and lungs can be simulated using PLA 100% infill $$ \left( {\rho_{e,w}^{130kV} = 0.99} \right) $$ and 20% infill plastic $$ \left( {\rho_{e,w}^{130kV} = 0.20} \right) $$.

John Paul Bustillo, Roy Tumlos, Randal Zandro Remoto

Dosimetry and Radiation Protection

Frontmatter

CT Spectrometry with a Portable Compton Spectrometer with Stationary and Moving Tube

The knowledge of energy spectra of CT X-ray beams is essential to completely characterize beam quality and equipment performance. However, CT photon fluxes are too high to be directly measured with most of photon counting detectors. This work describes a Compton spectrometer designed at LRDMP, based on a CdTe detector with proper Al–Pb-Al collimators and shields, to obtain spectra of CT beams, from the measured spectra of 90o-scattered beams. A MatLab® computer program, including the Waller-Hartree formalism, was developed, to correct measured data, and then reconstruct the spectrum of the beam incident on the scatterer. Tests at LRDMP with direct and scattered standard CT beams showed, after data processing and normalization, similarity between correspondent spectra of reconstructed and directly measured beams. Shielding and scatterer thickness influence were carefully investigated. The system was tested in clinical measurements in a GE690 CT scanner, using CT lasers and scout radiographies for alignment. HVL values obtained from the reconstructed spectra, with the stationary tube, agree within 3% with those measured in QC tests. We also double-checked, with good accuracy, the actual scattering angle and the kVp values, through the energy shift of K lines and spectra end point, respectively. Although several exposures might be necessary to acquire each spectrum with good statistics, the total acquisition time was no longer than two minutes for each one. Furthermore, measurements with rotating tube were made, showing that accumulated spectra shape are like those obtained with the stationary tube.

Ricardo Terini, Vincent Morice, Denise Nerssissian, Elisabeth Yoshimura

Evaluation of Effective Energy Distribution of 320-Multidetector CT Using GAFCHROMIC EBT3

Knowledge of the effective energy of 320-multidetector computed tomography (CT) is important for quality assurance and quality control. Evaluation in two dimensions is necessary because the effective energy varies depending on the shape of the wedge filter located in the CT device. The purpose of this study was to measure the two-dimensional effective energy distribution of the CT using GAFCHROMIC EBT3 (EBT3), which has a weak energy dependence. The exposure parameters of the 320-multidetector CT were 120 kV, 500 mA, and 5.0 s, and the X-ray tube was stopped at the 0 o’clock position. To avoid scattered radiation, the distance between the EBT3 and other scatterers was set to 200 mm or more. The Al filter thickness was increased from 2 to 20 mm. The irradiated area was divided into 54 compartments, and the density attenuation ratio was measured. The half-value layers (HVLs) were determined using the density attenuation ratios. The effective energies were obtained from the HVLs, and the two-dimensional effective energy distribution was evaluated. Because the thickness of the wedge filter in the longitudinal direction (parallel to the bed) remained unchanged, the variation in the effective energy was negligible in this direction. On the other hand, in the lateral direction (perpendicular to the bed), because the wedge filter gradually thickened from the center to the side, the effective energy from the center to the side increased. The two-dimensional effective energy distribution of the CT could thus be measured using EBT3.

Tatsuhiro Gotanda, Toshizo Katsuda, Rumi Gotanda, Takuya Akagawa, Tadao Kuwano, Nobuyoshi Tanki, Hidetoshi Yatake, Yasuyuki Kawaji, Takashi Amano, Shinichi Arao, Atsushi Ono, Akihiko Tabuchi

Monte Carlo Calculations of Skyshine Neutron Doses from an 18 MeV Medical Linear Accelerator

Neutron skyshine doses were calculated using a Monte Carlo code, FLUKA, by changing the heights and openings of shield walls. In the calculation geometry, the distance from the floor of the room to the roof was varied from 3 to 10 m. The target into which electrons were injected was located at a height of 2.3 m. The distance between the shield wall and target was varied from 1.5 to 5.79 m. Further, the height of the atmosphere was varied from 10 to 40 m. Consequently, the dose outside the shield wall increased with the height of the atmosphere and became saturated at 30 m; the neutrons reaching the ground were observed to be scattered mostly below 30 m. For neutron skyshine, NCRP Report No. 51 provided an expression stating that the neutron dose at ground level was proportional to the solid angle of shield walls and inversely proportional to the square of the distance from the target to the ceiling plus 2 m. In the Monte Carlo results, the doses conformed to the expression below a height of 5 m and above a distance of 2.6 m from the target to the shield wall. Under other conditions, the doses became higher than those predicted by the expression, which indicated the large contribution of neutrons emitted immediately above the target to the skyshine doses.

Nobuteru Nariyama

Evaluation in the Use of Bismuth Shielding on Cervical CT Scan Using a Female Phantom

Computed Tomography (CT) has become an important tool to diagnose cancer and to obtain additional information for different clinical questions. Today, it is a very fast, painless and noninvasive test that can be performed high quality images. However, CT scans usually require a higher radiation exposure than a conventional radiography examination. The aim of this study is to determine the dose variation deposited in thyroid and in nearby radiosensitive organs, such as: lenses, pharynx, hypophysis, salivary gland, spinal cord and breasts with and without the use of bismuth shielding. A cervical CT scan was performed on anthropomorphic female phantom model Alderson Rando, from the occipital to the first thoracic vertebra, using a GE CT scanner, Discovery model with 64 channels. Dose measurements have been performed by using radiochromic film strips to recorder the individual doses in the organs of interest. After the phantom cervical CT scan, the radiochromic film strips were processed for obtaining digital images. Digital images were worked to obtain the dose variation profiles for each film. With the data obtained, it was found the organ dose variation. The results show us that the thyroid received the highest dose, 24.59 mGy, in the phantom, according to the incidence of the primary X-ray beam.

Fernanda Stephanie Santos, Priscila do Carmo Santana, Thessa Cristina Alonso, Arnaldo Prata Mourão

Temporal Characterization of the Flat-Bed Scanner Influencing Dosimetry Using Radiochromic Film

Radiochromic films (RFs) have been developed for the measurement of the absorbed dose of low-energy photons. RFs are self-developing and radiation sensitive, and the amount of darkening is proportional to the absorbed dose. RFs are easy to handle due to their insensitivity to interior room light. However, the precision of the measurement has been questioned because of the change in density caused by the scan timing of the image acquisition using a flat-bed scanner. In this study, the density change of a flat-bed scanner was investigated using the temporal and the repetition scans. To obtain the image density, Gafchromic XR-QA2 films (XR-QA2s) were irradiated at 0 and 20 mGy (air-kerma) using 75 kVp (30 keV). The XR-QA2s were scanned every hour (0–6 h) from power activation to investigate the temporal light source change of a flat-bed scanner (EPSON ES-10000G). In addition, ten consecutive scans were performed every hour. The scan parameters were RGB (48-bit) mode, 100 dpi, and reflection mode. Image data of the XR-QA2s were divided into R, G, and B modes, and the R (16-bit) mode was used. The temporal light source change after power activation was small. However, in ten consecutive scans, the density of the first scan was the highest. The densities decreased with more scans. This result indicated that the precision of the dose measurement has about a 3% error due to the repeated scans. To obtain an accurate dose measurement, the image data obtained under the same conditions, such as the same time from power activation or same number of consecutive scans, must be used.

Rumi Gotanda, Toshizo Katsuda, Tatsuhiro Gotanda, Nobuyoshi Tanki, Hidetoshi Yatake, Yasuyuki Kawaji, Tadao Kuwano, Takuya Akagawa, Akihiko Tabuchi, Atsushi Ono, Shinichi Arao

The Relationship Between Eye Lens Doses and Occupational Doses for Different Centres of Interventional Cardiology

This study shows the level of eye lens doses and the relationship between eye lens doses Hp(3) and doses above the apron Hp(10) for 14 interventional cardiologists in 3 different centres of interventional cardiology. The doses were measured repeatedly with TLDs simultaneously placed above the apron and close to the left eye. For each patient’s procedure, the kerma-area product value (PKA) was known; values of Hp(3) and Hp(10) above the apron were normalized to total patients’ doses for procedures performed by a given cardiologist in the measuring period. The Hp(10)/PKA values for IC 1: IC 2 : IC 3 were as follows: 0.19 : 0.69 : 0.35 μSv/Gy*cm2 respectively. The Hp(3)/PKA values for IC 1 : IC 2 : IC 3 were as follows: 0.15 : 0.34 : 0.29 μSv/Gy*cm2 respectively. The values in IC 1 were 2–4 times lower than in IC 2 and IC 3. The expected annual Hp(3) doses were estimated; the highest was almost 16 mSv, the lowest 2 mSv. The results show different approaches to occupational radiation protection by cardiologists in the three centres (the use of an automatic contrast medium injector, shielding placed on patients to absorb scatter radiation from patients) as well as different approaches by cardiologists within the same centre. The local practice in IC 1 was more dose-saving than in the other centres. The values of Hp(10)/Hp(3) were reproducible for each cardiologist, so the Hp(10) value could be used for a retrospective estimation of the eye lens dose when needed, even when the eye lens dosimeter was not worn.

Lucie Sukupova, Zina Cemusova

Radiotherapy Dose Measurements Using a Fluorescing Quinine Solution

Quinine solutions fluoresce when exposed to ionising radiation, through the production and absorption of Čerenkov radiation. This study evaluated the feasibility of using ‘household’ tonic water as a radiotherapy dosimeter. Tonic water samples were irradiated with static beams for a variety of energies and dose rates: 6 and 10 MV photons at 600 MU/min; 6 MV flattening-filter-free photons at 1400 MU/min; 6, 9, 12, 15 and 18 meV electrons at 400 MU/min and 6 meV electrons at approximately 2474 MU/min (used for total skin electron irradiation). A sliding window IMRT field was delivered using a 6 MV photon beam at 600 MU/min, to assess dynamic response. Fluorescence was successfully recorded using a monochrome low light CCD camera placed on the treatment couch as well as the treatment room visual monitoring system in the linear accelerator control area. Energy dependence and dose rate independence were observed. While limitations in the bit-depth and focal length of the camera prevented precise quantitative analysis of depth dose profiles for conventional dose rates (≤600 MU/min), performance for higher dose rates (in terms of signal-to-noise in depth dose profiles) was comparable to radiochromic film. Potential use includes measurement of dose in the build-up region, efficient checks of beam energy and tomographic reconstruction of 4D dose delivery, though further optimisation of fluorescent signal acquisition is required.

Scott Crowe, Steven Sylvander, Tanya Kairn

Linac Leakage Dose Received by Patients Treated Using Non-coplanar Radiotherapy Beams

As non-coplanar beams are increasingly used to deliver cranial and extra-cranial stereotactic radiotherapy treatments, radiation leakage from the accelerating waveguide, bending magnet and other components of the medical linear accelerator (linac) that are not conventionally brought into proximity to the patient becomes increasingly concerning. In this study, the leakage dose in the patient plane was measured using optically stimulated luminescence dosimeters placed along the treatment couch, at 10 cm intervals. A Varian iX linac was operated in 6 and 10 MV photon mode, with all jaws and multi-leaf collimators closed. Dose measurements were made (a) using a “standard” setup, with couch and gantry at zero degrees and (b) using a worst-case non-coplanar setup, with the couch at 90° and the gantry at 30° (rotated over the couch). Results indicated that the leakage dose in the patient plane was uniformly low (less than 2 cGy/10,000MU) at all measurement positions for both energies, using the standard setup. However, when the gantry and couch were rotated, there was a systematic increase in dose to 4.2 cGy/10,000MU at a point 80 cm from isocentre (below the bending magnet). While these doses are within recommended out-of-field dose limits for static beam treatments, if IMRT/VMAT factors are applied then the leakage dose to the patient from non-coplanar treatments may become unacceptable. Specific checks of out-of-field dose from non-coplanar beam directions are advisable prior to acceptance of new or modified linacs.

Tanya Kairn, Scott Crowe, Samuel Peet

Optically Stimulated Luminescence Dosimeters as an Alternative to Radiographic Film for Performing “Head-Wrap” Linac Leakage Measurements

The linac “head-wrap”, where a new or modified linac is covered with radiographic film as a means to identify regions of increased radiation leakage, is an important part of the linac acceptance/commissioning process. However, as radiographic film and developing equipment decrease in availability and increase in cost, a simple, reusable, non-chemical solution becomes increasingly desirable. This study investigated whether discrete dose points measured using optically stimulated luminescence dosimeters (OSLDs) could be used to detect regions of increased radiation, as a substitute for radiographic film. After establishing the ability of the OSLDs to detect leakage and differentiate between high and low leakage doses, via a set of proof-of-concept measurements made in known high and low leakage regions on a Varian iX linac, a systematic evaluation of leakage at the surface of the linac head was undertaken. 60 OSLDs were positioned at regular intervals over the linac head by a member of the research team who was unfamiliar with the expected patterns of linac leakage. The OSLD measurements were able to detect linac head leakage and quantify high and low doses (from 0.6 to 44.7 cGy per 10,000 MU) with sufficient geometric precision to guide the use of an ionisation chamber to measure leakage doses in the patient plane. Reusable point dosimeters such as OSLDs are a promising solution to the problem of diminishing availability of film stock for linac head-wrap tests.

Tanya Kairn, Holly Stephens, Scott Crowe, Samuel Peet

Measurement of Percentage Depth-Dose Profiles in Very Small Fields

This study aimed to develop a method for accurately measuring small field percentage depth-dose (PDD) profiles. An SNC 3D Scanner cylindrical water tank (Sun Nuclear Corp, Melbourne, USA) was used in combination with an unshielded PTW diode 60017 (PTW Freiburg GmbH, Freiburg, Germany) to measure PDDs in very small radiation beams from a Varian Truebeam STx linac (Varian Medical Systems, Palo Alto, USA). Two PDD measurement methods were investigated; (a) a ray-tracing technique, where a complex automated process was used to continuously drive the diode into the centre of the field while varying the measurement depth, and (b) a conventional technique, where the centre of each field was identified using orthogonal profile scanning and then the tank platform was iteratively shifted to place the diode at the centre of the field before PDD scanning. For both methods, the effects of the low measurement signal were mitigated by scanning very slowly (2 s integration times). The field size was reproducible within 0.1 mm even after collimator and carousel repositioning. Differences of up to 3% were identified between the PDDs measured using the conventional and ray tracing methods. Comparison of these results with PDDs from larger fields suggested that the ray-tracing method was over-measuring the dose (or under-measuring depth) in the very small fields. Although time consuming, the use of a PDD measurement technique where the centre of the field is identified manually is advisable, unless the reliability more sophisticated ray-tracing techniques can be convincingly established.

Shadi Khoei, Mark West, Tanya Kairn

Long-Term Reliability of Optically Stimulated Luminescence Dosimeters

Optically stimulated luminescence dosimeters (OSLDs) can be used as accurate and re-usable dosimeters for radiotherapy applications. OSLDs have been observed to decline in sensitivity with repeated use and it is important to determine whether this decline in sensitivity is associated with a decline in reliability. This study used three batches of OSLDs (purchased in 2012, 2014 and 2016) that had been repeatedly re-used in a mature in vivo dosimetry programme over a period of up to five years and evaluated the consistency of their response over repeated irradiation-readout-bleaching cycles. Each irradiation delivered 105 cGy to all OSLDs, using a 12 meV electron beam from a Varian iX linear accelerator. The five- and three-year-old OSLDs respectively displayed 86% and 89% of the sensitivity of the one year old OSLDs, but when a correction factor for each OSLD was derived based on the first measurement result and applied to each subsequent reading, all OSLDs were able to measure the 105 cGy test dose accurately, within standard deviations of 2.0% for the OSLDs from 2012 and 1.3% for the OSLDs from 2014 and 2016. If a mean calibration value was applied to the readings from each batch of OSLDs, instead of applying a measurement-derived sensitivity correction factor to each individual OSLD reading, the standard deviations increased to an unacceptable 6.1, 5.6 and 2.9%. Well-used three- and five-year-old OSLDs were shown to be capable of providing measurements with similar accuracy to a more recently-purchased batch of OSLDs, when measurement-derived sensitivity correction factors were applied to each result. If this extra step is included in the OSLD measurement process, then the same OSLDs may be reliably used for years without needing to be retired and replaced.

Tanya Kairn, Samuel Peet, Liting Yu, Scott Crowe

Feasibility Study of Alanine Dosimeter for Carbon-Beam Dosimetry

Alanine dosimeters are useful tools for measuring both kilo-gray level doses and radiation therapy level doses. The National Metrology Institute of Japan is planning to develop a dose measurement service for carbon-beam therapy. The purpose of this study was to verify that the alanine dosimeter could be used for carbon-beam dosimetry. We irradiated the alanine dosimeter with 60Co-gamma rays and a carbon beam using a range of 10–30 Gy. For the gamma-ray irradiation, the alanine dosimeter was placed in a 5 g cm−2 water phantom. For the carbon-beam irradiation, the spread out Bragg peak of the 290 meV/u carbon ion was used, and the dosimeter was located at the centre of the peak region. The alanine spectra obtained under the carbon-beam irradiation were almost the same as the spectra under the gamma-ray irradiation. The alanine dosimeter irradiated with the carbon beam show a smaller signal than that obtained under the gamma-ray irradiation for the same dose. The alanine signal increased as the dose increased over the entire dosage range for both the gamma-ray and carbon-beam irradiation. This result suggests that the alanine dosimeter has potential for carbon-beam dosimetry.

H. Yamaguchi, M. Shimizu, Y. Morishita, K. Hirayama, Y. Satou, M. Kato, T. Kurosawa, T. Tanaka, N. Saito, M. Sakama, A. Fukumura

Local Dose Survey on Paediatric Multi-detector CT: A Preliminary Result

For paediatric patients, where there exists a wide range of patient size, and where radiation risk is two to three times more prevalent than on adults, the need of a more stringent care on dose optimization becomes more crucial and demanding, particularly on computed tomography (CT) procedures. To first investigate the need of optimization, a preliminary dose survey was carried out by recording dose data from head, chest, and abdomen MDCT procedures for paediatric patients. The survey from a total of 343 paediatric CT patients was conducted on March-September 2017 at Harapan Kita Maternal and Children’s Hospital as Indonesia’s primary referral hospital for paediatric patients. Results per age group were compared with available works from other regions or countries to first indicate the need for optimization. The preliminary result indicated that head scans for 10–15 years old patients require optimization. The evaluation of protocol selections is proposed as an appropriate action.

L. E. Lubis, A. F. Jundi, A. Susilo, A. Evianti, D. S. Soejoko

Advantages in the Application of Conductive Shielding for AC Magnetic Field in MRI Exam Rooms

Due to the increasing demand for installation of Magnetic Resonance Imaging (MRI) equipment in clinics and hospitals, and the difficulty to choose the location for installation of these equipment because of their high sensitivity to 60 Hz magnetic field sources, this study was carried out to present a practical solution for shielding 60 Hz magnetic field in the hospital environment. MRI is a technique that produces 3-D (volumetric) tomographic images of high resolution without using ionizing radiations. The quality of images is greatly influenced by magnetic fields of the environment, especially of 50/60 Hz, which results in the need of shielding the space where the equipment are installed. This study proposes the use of aluminum in the construction of the MRI room shield for the many advantages presented by this material when compared to ferromagnetic materials: it is lighter, easier to handle, bend, rivet or weld, it does not rust and dispenses sturdy supports for fixing on walls, resulting in the best cost-benefits ratio in short and long terms. We performed computational simulation and experiments with shields of rectangular geometries assembled with aluminum and ferromagnetic materials. The aluminum shield has proved to be advantageous, since it presents shielding effectiveness to 60 Hz magnetic field similar to those of Fe–Si GNO under certain conditions, and radio frequencies shielding also, with lower cost in the installation and maintenance of shielding in MRI rooms.

Rafael Navet de Souza, Sergio Santos Muhlen

Development of Optical Computed Tomography for Evaluation of the Absorbed Dose of the Dyed Gel Dosimeter

Optical computed tomography (optical CT) is a reading device of the dyed gel dosimeters. We are developing the optical CT for the evaluation of three dimensional radiation absorbed dose distribution in the dyed gel dosimeters. We made dyed gel with leuco crystal violet and the dyed gel will be contained in vials. The dyed gel dosimeters were irradiated with 10 MV X-ray beam at 100–2000 MU. The optical CT we developed was consists of a liquid crystal monitor VL-176SE (FUJITSU, Japan) as a light source and a camera uEye XS (iDS, Germany). The dyed gel dosimeter was rotated by a step of every 0.9° with the stepper motor ST-42BYH 1004-5013 (MERCURY MOTOR, China) in a water tank and be taken 400 projections per rotation. Volume data was reconstructed from the projection images with the image processing software Plastimatch. The correlation between the absorbed dose and signal values of the dyed gel dosimeters in the reconstructed image was analyzed. The developed optical CT could reconstructed the images of the dyed gel dosimeters and the signal values of the dyed gel dosimeters in the reconstructed images had linear response related to the dose up to 20 Gy.

Takuya Wada, Kazuya Nakayama, Akihiro Takemura, Hiroaki Yamamoto, Hironori Kojima, Naoki Isomura, Kimiya Noto

Assessment of Neonatal Entrance Surface Doses in Chest Radiographic Examinations at East Avenue Medical Center

A significant development in the initial diagnosis and evaluation of illnesses of neonates is the use of a chest x-ray. The technology is essentially useful to hospitalized and prematurely-born neonates suffering from respiratory and cardiovascular complications. Neonates are known to be more radiosensitive than adults because of the high mitotic rate of neonatal cells. They are also at a higher risk of inducing stochastic effects due to their long life expectancy. Despite such risk, physicians still require neonates to undergo radiographic examinations to monitor treatment progress while in the Neonatal Intensive Care Unit (NICU). Therefore, the radiation doses they receive during a radiographic examination should be kept at a minimum without compromising the diagnostic image quality. In this study, the entrance surface dose (ESD) for neonates undergoing diagnostic chest radiography in the NICU at East Avenue Medical Center was measured. The ESD for chest anteroposterior (AP) and lateral (LAT) projections ranges from 0.022 to 0.080 mGy and 0.023–0.080 mGy, respectively. Reference levels set by international organizations were used for benchmark comparisons with the results of the present study.

Franklyn Naldo, Bayani San Juan, Melanie Marquez

The Metrological Electron Accelerator Facility (MELAF) for Research in Dosimetry for Radiotherapy

The Metrological Electron Accelerator Facility (MELAF) of the Physikalisch-Technische Bundesanstalt (PTB) offers access to well characterized high-energy (0.5–50 MeV) electron and photon radiation fields also for external researchers. This work outlines the capabilities of the facility to foster new collaborations. As example, the experimental determination of ionization chamber typical correction factors for Magnetic-Resonance guided Radiotherapy (MRgRT) is presented.

Andreas Schüller, Stefan Pojtinger, Markus Meier, Christoph Makowski, Ralf-Peter Kapsch

Incidence of Burnout Among Medical Dosimetrists in Portugal

Burnout is a pathologic response to chronic occupational stress resulting from the lack of coping strategies that assist the individual to comply with the working demands. Burnout is a cause of serious consequences for both the individual and the organization. Given the lack of studies on the incidence of this disease in medical dosimetrists in Portugal, this study aims to compensate for this gap. The method used for data collection was a survey divided into three parts. The first part was designed to evaluate the sociodemographic and professional conditions of the sample. The second part of the survey was based on the Copenhagen Burnout Inventory (CBI) and the third part was based on the Maslach Burnout Inventory (MBI). The survey was distributed to all medical dosimetrists working in public and private institutions in Portugal which gave the authorization to participate in this study. We evaluated 17 medical dosimetrists (physicists and radiation therapists), engaged in six Portuguese public and private institutions. Our results reveal an incidence of burnout between 35.3% (CBI) and 88.2% (MBI), manifested by worrying results on the sub-scales of personal burnout, work-related burnout, emotional exhaustion and personal accomplishment. For this study, the questionnaires were adapted and tested, having been considered valid for the Portuguese population, however, more detailed formal validation should be carried out in future studies.

Dina Gonçalves, Ana Sucena

CT Extended Hounsfield Unit Range in Radiotherapy Treatment Planning for Patients with Implantable Medical Devices

Radiotherapy (RT) treatment planning is based on computed tomography (CT) images and traditionally uses the conventional Hounsfield unit (CHU) range. This HU range is suited for human tissue but inappropriate for metallic materials. To guarantee safety of patient carrying implants precise HU quantification is beneficial for accurate dose calculations in planning software. Some modern CT systems offer an extended HU range (EHU). This study focuses the suitability of these two HU ranges for the quantification of metallic components of active implantable medical devices (AIMD). CT acquisitions of various metallic and non-metallic materials aligned in a water phantom were investigated. From our acquisitions we calculated that materials with mass-density ρ > 3.0 g/cm3 cannot be represented in the CHU range. For these materials the EHU range could be used for accurate HU quantification. Since the EHU range does not effect the HU values for materials ρ < 3.0 g/cm3, it can be used as a standard for RT treatment planning for patient with and without implants.

Zehra Ese, Sima Qamhiyeh, Jakob Kreutner, Gregor Schaefers, Daniel Erni, Waldemar Zylka

3D Absorbed Dose Reconstructed in the Patient from EPID Images for IMRT and VMAT Treatments

A back-projection method has been used in this study to reconstruct the 3D absorbed dose matrix in the patient from EPID images for IMRT and VMAT fields. Images were acquired with the Clinac 23iX aS-1000 imager (Varian) and a 6 MV beam. Then a calibration step was performed to transform the grey levels of the pixels into absorbed dose in water via a response function. Correction kernels were also used to correct for the scatter within the EPID. The dose was then back-projected into the patient for all EPID parallel planes for each gantry angle. Finally the total dose was obtained by summing the 3D dose associated for each gantry angulation. First, the 3D dose reconstruction algorithm was tested for 20 IMRT and VMAT prostate and head and neck treatments in a homogeneous cylindrical phantom. Then the algorithm was used for IMRT brain cancer plans on 20 real patients. The EPID reconstructed 3D dose distributions were then compared to the planned dose from TPS (Treatment Planning System, Eclipse Varian) with a 3D global gamma index of 3% and 3 mm criteria. The percentage of points of which the gamma index was larger than unity was greater than 97% for all IMRT treatments both in the phantom and in the patients and over 96% for all VMAT treatments checked in the cylindrical phantom. Our 3D reconstruction algorithm, validated for homogeneous medium, can be used to verify the dose distribution for IMRT and VMAT fields using in vivo EPID images.

Fouad Younan, Jocelyne Mazurier, Frederic Chatrie, Ana Rita Barbeiro, Isabelle Berry, Denis Franck, Xavier Franceries

Implementation of a Novel Uncertainty Budget Determination Methodology for Small Field Dosimetry

This paper presents the implementation of a novel methodology for the determination of the uncertainty associated to the process of beam measurement in small fields. Field output factors were measured for different fields sizes in a 6 MV photon beam. The uncertainties related to the detector’s positioning were taken into account, as well as its characteristics. Contributions of the beam limiting device, scanning system, instrumental and correction factors introduced for field output factor calculations were also analyzed. A broad range of detectors, including ionization chambers with different active volumes and one stereotactic diode for radiosurgery were used. Expanded uncertainty levels under 3% for k = 3 were obtained with the stereotactic diode for all the studied field sizes. Ionization chambers’ uncertainty levels were substantially larger in most cases.

David Eduardo Tolabin, Rodolfo Alfonso Laguardia, Sebastian Bianchini

Fundamental Research and Experimental Work on Properties of Tungsten Micro- and Nanoparticle Structured Composite Material

Tungsten micro- and nanoparticle structured composite have been demonstrated recently as a promising material for protection of the radiation therapy patient against radiation. The shielding properties of the composite to a great extent depends on the homogeneity. The present research concentrates on the experimental investigation of the homogeneity of the synthesized composite in dependence on the material mixing methods, particle size, and concentration. The material radiation attenuation properties were explored as well. It was observed that the tendency to form agglomerates becomes greater if tungsten particle size decreases. The best particle distribution uniformity in the composite was obtained with ultrasound disperser. Most effective radiation absorption was observed for the samples with a particle size of 500 nm and 50 nm.

G. Boka, Y. Dekhtyar, S. Bikova, Y. Bauman, P. Eizentals, A. Svarca, M. Kuzminskis

Assessment of Low Doses During Diagnostic Procedures Using BeO Detectors and OSL Technique

Advances in imaging techniques with the use of radiation increased the quality and power of medical diagnostic. At the same time, concerns about the doses to patients arose in the radiation protection community. According to UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation), the second main contribution to the population annual dose is from exposure in medical procedures. Although the doses are relatively low in diagnostic, the number of exams for the same patient is growing, bringing especial attention to doses to children or to radiosensitive regions in the body. International organizations recommend the establishment of reference levels in diagnostic procedures and the tracking of the patient exposures. Considering this, we studied the use of optically stimulated luminescence (OSL) and thermoluminescent (TL) techniques together for assessment of skin doses in simulated (pediatric phantom) and real patients during diagnostic procedures. BeO and LiF detectors were used in mammography and radiographic procedures, and in CT examinations. The results of TL and OSL were compared to each other and to international reference levels, when it was possible. Both detectors were able to evaluate doses in the range of 15 µGy to 100 mGy. BeO detectors presented compatible results with LiF detectors for doses in the range of few mGy and low uncertainties in the range of µGy, for both, adults and pediatric patients. We can conclude that the advantages of OSL technique combined to intrinsic characteristics of BeO (tissue equivalence and flat energy response for photons up to 100 keV) can be explored for assessment of patient doses in diagnostic procedures.

Anna Luiza M. C. Malthez, Ana Clara Camargo, Ana Paula Bunick, Danielle Filipov, Celina Furquim, Elisabeth Yoshimura, Nancy Umisedo

Development of a Patient Dosimetry Record System in an Oncological Hospital in Mexico

Medical imaging studies represent an important tool for patient diagnosis. However some may be harmful due to the amount of ionizing radiation used in them, this is the main reason why it is necessary to keep track of the dose received by each patient. There are many countries in which, as a norm, a dosimetry record of each patient who has undergone imaging studies using ionizing radiation is taken. Mexico is trying to implement this kind of registration, however, commercial systems are still not available. The aim of this article is to describe the development and implementation of a system that allows doctors to assess and monitor the total effective dose of each patient. This system is aimed to work under the consideration of certain requirements and as long as the right protocols are taken.

Reyna O. M. González, Gerardo A. D. Enríquez, Sandra N. L. Rocha, Rafael S. Samra, Jorge L. P. Castillo, Yolanda N. Villaseñor, Hector E. Galván

Electronic Portal Imaging Devices Using Artificial Neural Networks

The aim of this work was to use the Artificial Neural Network (ANN) in External Beam Radiation Therapy (EBRT), especially for pre-treatment patient-specific quality assurance of Conformational Radiation Therapy (CRT) and Intensity-Modulated Radiation Therapy (IMRT) using Electronic Portal Imaging Device (EPID). The EPIDs need frequent calibration and complex setting in order to be used with dedicated dosimetry software. The idea was to create a model with ANN algorithms allowing the reconstruction of the 2D dose distribution comparable with a corresponding Treatment Planning System (TPS) solution. The supervised ANN algorithms work with two phases—learning and recognition. Learning was performed using data sets regarding CRT and IMRT composed of 8 and 11 input/output respectively. To compare ANN predicted and planned results the global gamma index was used, obtaining a $$ \gamma_{{(2\% ,2\,\text{mm})}} = 99.78\% $$ and $$ \gamma_{{(2\% ,2\,\text{mm})}} = 99.7\% $$, respectively. This first work showed the capability of ANN to reconstruct the absorbed dose distribution based on EPID signals.

Frédéric Chatrie, Fouad Younan, Jocelyne Mazurier, Luc Simon, Laure Vieillevigne, Régis Ferrand, Ana Rita Barbeiro, Marie-Véronique Le Lann, Xavier Franceries

Study of the X-Ray Attenuation as a Function of the Density and Thickness of the Absorbent: Cortical Bone and BaSO4

In the present paper a non-metallic material to attenuate X-rays is proposed, mainly for medical imaging applications in order to reduce the radiation dose received by patients due to dispersion. For this purpose, the filing of cortical bone and barium sulfate (BaSO4) were characterized using X-ray diffraction, energy-dispersive X-ray analysis and Raman spectroscopy techniques. Attenuation capacity of the X-rays was determined using an X-rays equipment (10–30 kV) and a Geiger-Müller detector, bearing in mind that the intensity of the transmitted radiation depends on the thickness and density of the material, having a 1 mm lead sheet as reference. In addition, a radiation attenuation comparison dose emmited by a dental X-ray generator using TLD-100 thermoluminescent crystals and periapical radiographic plates is presented, identifying that BaSO4 is the material that attenuates the better this type of radiation compared to cortical bone.

Andrea Vargas-Castillo, Angel M. Ardila

Development of 3D Printed Phantom for Dose Verification in Radiotherapy for the Patient with Metal Artefacts Inside

One of the problems performing IMRT dose planning or plan verification using anthropomorphic phantoms for head and neck cancer patients is the presence of possible artefacts (dental crowns, metal dental implants, dental restoration materials.) inside the oral cavity. In many cases these artefacts are not accounted but may cause deviations from patient treatment plans due to enhanced scattering dose from the metal artefacts. Exploiting 3D printing technologies 3D dosimetry phantom corresponding to patient-specific anatomic structures with precisely positioned artefacts can be produced. Application of such 3D phantom in radiation therapy may contribute to more accurate dose planning and thus more efficient patient treatment. In this work we propose newly developed patient-specific 3D printed phantom of lower jaw with teeth which can be used for patient specific QA in IMRT. Developing this phantom DICOM image of the real patient was used for 3D reconstruction of patient’s lower jaw with teeth. 3D shape of this anatomic structure was printed out using Zortrax M300 3D printer. High Impact Polystyrene (HIPS) which is characterized as having satisfactory bone tissue equivalency was used as printing material. Keeping in mind a real patient, possibility of covering of corresponding teeth with a metallic crown in the 3D printed jaw construction was foreseen. Prepared construction was fixed in dose gel matrix, thus forming dosimetry phantom for the evaluation of possible radiation treatment errors caused by artefacts located in this anatomic region of the patient. Investigation of 3D printed lower jaw phantom has shown its feasibility for the assessment of dose distortions related to the presence of metal artefacts in the mouth of the patient. Also potential for the application of 3D printed phantoms in radiotherapy quality assurance has been shown.

Diana Adlienė, Evelina Jaselskė, Benas Gabrielis Urbonavičius, Jurgita Laurikaitienė, Viktoras Rudžianskas, Tadas Didvalis

Advances Technologies in Cancer Research and Treatment

Frontmatter

Magnetic Resonance Cancer Nanotheranostics

It is well known that the magnetic spin effects during nanotherapy can cause tumor cell apoptosis and necrosis based on redox reactions. The current study was carried out on C57Bl/6 mice with Lewis lung carcinoma. The magnetic nanocomplex administration combined with the impact of magnetic resonance system (1.5 T) showed maximal antitumor and antimetastatic effects. The electron spin resonance spectra have been used as diagnostic markers and recorded a change in the tumor redox state based on chemical species such as NO-FeS-proteins and ubisemiquinone. The technology of magnetic resonance nanotheranostics could potentially allow to improve the antitumor effect of chemotherapeutic agents in disseminated cancer therapy.

V. E. Orel, M. Tselepi, T. Mitrelias, A. D. Shevchenko, O. Y. Rykhalskiy, T. S. Golovko, O. V. Ganich, A. V. Romanov, V. B. Orel, A. P. Burlaka, S. N. Lukin, C. H. W. Barnes

Development of a Spherical Ultrasound Transducer for Transcranial Low-Dose Ultrasound Hyperthermia Used in Brain Tumor Nanodrug Delivery

Previous studies showed that low-dose focused ultrasound hyperthermia (UH) could enhance the delivery and therapeutic efficacy of nanodrug for brain metastasis of breast cancer. In this study, our purpose is to design an ultrasound transducer that can be used for clinical application for brain tumor nanodrug delivery. Computer simulation has been used to calculate the pressure field, temperature distribution and thermal dose in the brain for different parameters of a spherical array ultrasound transducer. An ultrasound transducer with 112 disc elements (1 MHz, 2 cm in diameter) was constructed and its heating ability was characterized using a skull phantom filled with hydrogel. The simulation results showed that the position of peak pressure was slightly offset when the transducer was mechanically moved 3 cm away from the center point in all directions. There was no significant side-lobe developed when the transducer was moved away from the center 2 cm. Temperature distribution showed that the heating zone was an ellipsoid with temperature higher than 42 °C for a maximum intensity of 121 W/cm2. Phantom experiment showed that the 42 °C color-changeable hydrogel would turn to be white at the focal point when the transducer was moved 2 cm in all directions with an electrical power 55 W. A spherical ultrasound phased array was developed and characterized, and the results showed that this ultrasound transducer has the potential used in transcranial short-time ultrasound hyperthermia for brain tumor nanodrug delivery.

Chun-Chiang Shen, Gin-Shin Chen, Yung-Yaw Chen, Win-Li Lin

An in Vitro Phantom Study to Quantify the Efficacy of Multi-tine Electrode in Attaining Large Size Coagulation Volume During RFA

The present study aims at evaluating the efficacy of commercially available RITA’s StarBurst® XL multi-tine electrode in attaining large size coagulation volumes (≥3 cm in diameter) during radiofrequency ablation (RFA) application. In vitro studies have been conducted on the cylindrical shaped polyacrylamide based tissue-mimicking phantom gels utilizing different active lengths of the multi-tine electrode, viz., 2 cm, 3 cm, 4 cm and 5 cm. A temperature-controlled RFA has been performed at a target tip temperature of 95 °C for 5 min. The variations in the power supply, the target tip temperature and the size of coagulation volume have been reported for different active lengths of the multi-tine electrode. The study revealed that the increase in active length of the multi-tine electrode results in more energy deposition and consequent rise in the coagulation volume during RFA procedure. Further, a simplified novel statistical correlation between the coagulation volume and active length of the multi-tine electrode has been proposed.

Sundeep Singh, Ramjee Repaka

Temperature-Induced Modulation of Voltage-Gated Ion Channels in Human Lung Cancer Cell Line A549 Using Automated Patch Clamp Technology

In cancer cells specific ion channels exhibit altered channel expression, which can drive malignant and metastatic cell behavior. Hence, therapeutic strategies modulating ion channels prove to be promising in cancer therapeutics. Alterations in temperature, even small deviations from normothermia, may cause changes in electrophysiological processes, since activation and conductivity of various ion channels are temperature-dependent. In this pilot study, we focused on a basic understanding of the effects of temperature-alterations on voltage-gated ion channels of A549 cells using an automated patch-clamp system. The measurements were carried out in whole-cell voltage-clamped configuration applying test pulses between −60 and +60 mV. For positive voltages the ion-current curves showed an instantaneously increased conductance, followed by a slow current increase provoked by later activating voltage-gated ion channels, indicating the time-delayed response of additional channels. To investigate the temperature-dependent electrophysiological behavior, six cells (passages 7–10, n = 34) were examined at room temperature and normal body temperature. Compared to normal body temperature, reduced temperatures revealed a higher whole-cell current at negative voltages (63.4% (±18.5%), −60 mV) and lower currents (52.6% (±27.3%), +60 mV) at positive voltages, indicating a hypothermia-induced modulation of voltage-gated channels in the lung cancer cell line A549.

Sonja Langthaler, Katharina Bergmoser, Alexander Lassnig, Christian Baumgartner

Biological Effects of Ionizing Radiation

Frontmatter

A Volumetric Delta TCP Tool to Quantify Treatment Outcome Effectiveness Based on Biological Parameters and Different Dose Distributions

Intra-tumor variability of oxygenation and clonogenic cell density causes tumor non-uniform spatial response to radiation. Strategies like dose redistribution/boosting, whose impact should be quantified in terms of tumor control probability (TCP), have been proposed to improve treatment outcome. In 1999, Sánchez-Nieto et al. developed a tool to evaluate the impact of dose distribution inhomogeneities, compared to a reference homogeneous dose distribution, in terms of TCP. DVH data were used to calculate the so-called ∆TCP, defined as the difference in TCP arising from dose variations in individual DVH-bins. In this work, we develop an open source tool to calculate volumetric ∆TCP and evaluate the impact on TCP of: (i) Spatial dose distribution variations with respect to a reference dose; (ii) Spatial radiosensitivity variations with respect to a reference radiosensitivity; (iii) Simultaneous variation in dose distribution and radiosensitivity. ∆TCP calculations can be evaluated voxel-by-voxel, or in a user defined subvolume basis. The tool capabilities are shown with 2 examples of H&N RT treatments and subvolume contours data providing information about tumor oxygenation status. ΔTCP values are computed for a homogeneous dose to a well oxygenated tumor volume (with a homogeneous 5% vascular fraction), as reference condition, with respect to the same dose now considering 3 oxygenation levels and 3 cell density values (104, 106 and 107 cells/mm3, respectively). ΔTCP values are also computed for the comparison of a homogenous dose distribution vs a redistributed dose distribution delivered to the non-homogeneous tumor.

Daniella Fabri, Araceli Gago-Arias, Teresa Guerrero-Urbano, Antonio Lopez-Medina, Beatriz Sanchez-Nieto

Nuclear Medicine and Molecular Imaging

Frontmatter

Establishment of an Analysis Tool for Preclinical Evaluation of PET Radiotracers for In-Vivo Imaging in Neurological Diseases

Aim: Analysis of in vivo acquired data remains a challenging issue in preclinical studies using positron emission tomography (PET). The aim of this study is the implementation of a tool which should allow a semi-automated analysis of PET data independently from the administrated radiotracer and the imaging modality for preclinical investigations. By registering anatomical data sets, it additionally shall offer a more detailed data analysis allowing a statistical analysis also for smaller sub-regions. Materials and methods: Data used for primarily implementation of the tool were acquired on a Siemens µPET scanner (Inveon®) and were based on the investigation of the glucose metabolism in a subarachnoid hemorrhage (SAH) model in Sprague Dawley rats in vivo using FDG-PET. We used the software programs Matlab (version 2016a) and Fiji for data analysis and visualization. In addition, statistical tests were performed in order to determine regions with trending/significant differences in the SUV of sham and SAH animals. Results: Following data import, data were separated into predefined time periods and artefacts were eliminated. Afterwards, a volume of interest (VOI) was defined by the threshold of the Standardized-Uptake-Value (SUV). Before masking each data set with its segmented VOI, all data sets were intensity-normalized, eliminating the full body intensity differences caused by the different amount of injected activity. After masking, data sets of the sham operated animals were registered on the best orientated sham data set, reduced on the VOI and shifted into the center of the 3D space. By averaging aligned data sets based on all data sets from seven sham rats, we generated a FDG-template of a Sprague-Dawley rat brain. This PET data template was the basis for the evaluation of registered data sets. Afterwards, an anatomical MR-based atlas of the brain of Sprague-Dawley rat was co-registered on the template for a better sub-classification of the acquired data. Conclusion: These preliminary data show that the described method represents a very promising tool for data analysis in the preclinical evaluations of PET radiotracers for neurological applications.

Fabian Schadt, Samuel Samnick, Ina Israel

Radio-Guided Surgery with β− Radiation: Tests on Ex-Vivo Specimens

Radio-Guided Surgery (RGS) is a surgical technique aimed at assisting the surgeon to reach as complete a resection of the tumoural lesion as possible. Established methods to date make use of $$ \gamma $$-emitting tracers to radio-mark the neoplastic tissue. However, in case of uptake from healthy organs around the lesion the large penetration of photons yields a non-negligible background that can limit the RGS application. The adoption of $$ \beta^{ - } $$ radiation has been proposed to overcome this limit. To validate the entire RGS procedure, from the evaluation of the tracer uptake of the tumor, to the assumptions on the bio-distribution and the signal detection, tests on ex vivo specimens of meningioma brain tumour were performed. Meningioma was selected due to the well known high receptivity to a $$ \beta^{ - } $$ emitting radio-tracer already in use in the clinical practice: 90Y-labelled DOTATOC. Patients were enrolled according to the tumour Standard Uptake Value (SUV $$ > $$ 2) and the expected Tumour to Non-tumour Ratio (TNR $$ > $$ 10) estimated from 68Ga-DOTATOC PET images. After injecting the patients with 93–167 MBq of $$ ^{90} Y - DOTATOC $$, 26 samples excised during surgery were examined with a dedicated $$ \beta^{ - } $$ detecting probe to assess the sensitivity of millimetre-sized tumour remnants in case of administration of low activity value compatible with those injected for diagnostic exams. Even injecting as low as 1.4 MBq/kg of radio-tracer, tumour remnants greater than 0.06 ml would be discriminated by the healthy tissue in few seconds.

C. Mancini-Terracciano, V. Bocci, M. Colandrea, F. Collamati, M. Cremonesi, R. Faccini, M. E. Ferrari, P. Ferroli, F. Ghielmetti, C. M. Grana, M. Marafini, S. Morganti, S. Papi, M. Patané, G. Pedroli, B. Pollo, A. Russomando, M. Schiariti, G. Traini, E. Solfaroli Camillocci

Investigation of Time-Activity Curve Behavior in Dynamic [11C]-(R)-PK11195 PET in Cortical Brain Regions: Preliminary Results

Dynamic Positron Emission Tomography (PET) allows quantification of underlying physiological processes in a tissue or organ of interest by modeling the radioactivity concentration measured in time (time-activity curve, i.e. TAC). Although the [11C]-(R)-PK11195 PET radiotracer binds to activated microglia and therefore images neuroinflammation, its quantification is still challenging. The aim of this study was to investigate a novel method for analyzing [11C]-(R)-PK11195 TAC behavior from dynamic PET. Seven healthy subjects underwent dynamic 60 min [11C]-(R)-PK11195 PET scans, and TACs were generated for 30 brain cortical regions using the AAL-Merged atlas. The proposed method supposes healthy subjects have similar TACs, which allows the construction of a “healthy template”. Then, TACs of patients can be compared to the healthy template to determine the likelihood that their behavior is abnormal. To evaluate the differences between a healthy region and an inflamed region, a cut-off value for abnormality was created. The method was then tested on a multiple sclerosis (MS) patient. The proposed method was able to identify a number of brain cortical regions with distinct behavior in one MS patient as compared to the healthy template. Further studies are required to evaluate the applicability of the proposed method with additional MS patients, and with data acquired in different scanners and reconstructed with other algorithms.

Giordana Salvi de Souza, Ana Maria Marques da Silva

Image Quality Performance of a Dedicated Cardiac Discovery NM 530c SPECT: Impact of Time Acquisition and Reconstruction Parameters

The aim of this study is to evaluate the impact of acquisition time and reconstruction parameters in image quality in a dedicated cardiac Discovery NM 530c CZT SPECT scanner. Anthropomorphic torso phantom with a cardiac insert and a cold lesion starting with 84 kBq/ml, 62 kBq/ml and 3 kBq/ml in myocardium, liver and background, respectively, simulated high-dose stress 99mTc acquisition. During two half-lives, images were acquired hourly to simulate lower doses, using both 3 and 5 min time acquisition. Reconstruction parameters were used separately per type of acquisition (low-dose and high-dose), according to manufacturer recommendation. Image quality and cold lesion visibility were evaluated using normalized standard deviation (NSD), ventricle-wall cavity contrast (VCC), contrast-to-noise ratio (CNR), and lesion effective contrast (EC). Variations in acquisition time did not affect quality parameters and lesion visibility for the appropriate reconstruction parameters, mainly in higher activities. However, image quality indicators are highly sensitive to the reconstruction parameters, producing significant differences (p < 0.05) in NSD, VCC, CNR and EC. Concluding, the reconstruction parameters need to be chosen carefully, considering patient´s characteristics and administered activity, in order to produce the best relation image quality/lesion visibility and dose.

Mariana Saibt Favero, Ana Maria Marques da Silva

Innovative Biomedical Engineering Research in Asia

Frontmatter

A Surgical Robotic System for Transurethral Resection

Transurethral surgery is a noninvasive interventional procedure that delivers a tubular surgical instrument via the urethra to access surgical sites in the prostate or bladder for abnormal tissue resection. In the clinical practice, a rigid resectoscope is inserted via the urethra to access the surgical site. The resectoscope is manually operated by the surgeon. Due to the limited field of the view (FOV) of the resectoscope, difficult hand-eye coordination, hand tremor, and lack of depth perception, the procedure is laborious, having a risk of perforation and damage to healthy tissue. We develop a master-slave robotic system for transurethral resection. The system is composed by a user console and a slave robot. The user console provides surgical vision and intuitive human-robot interaction interface, and the slave robot performs the surgery accordingly. The slave robot further consists of a 6 DOFs (degree of freedom) serial robot arm and a 1 DOF end-effector. The robot arm is used to accurately position and orient the resectoscope inside the body. The end-effector is designed to hold the resectoscope and precisely implement the linear motion of the cutting loop by reproducing the user’s operation at the console side. Preliminary experiments were performed to evaluate the proposed system and the results have confirmed its effectiveness.

Junchen Wang, Jiangdi Zhao, Xuquan Ji, Xuebin Zhang, Hanzhong Li

Sophisticated Hydrodynamic Simulation of Pulmonary Circulation for the Preclinical Examination of Right Heart Circulatory Assist Device

To evaluate systemic circulatory support devices such as left ventricular assist system, surgical heart valve prosthesis, and transcatheter aortic valve, various in vitro hydrodynamic tests have been performed. As these devices are being applied to the pulmonary circulatory support in recent years, novel evaluation platform for right heart support is increasingly demanded. This study aims to develop a pulmonary mechanical circulatory simulation system to assess the hydrodynamic performance of newly designed artificial cardiovascular devices. For the construction of the system, we developed the pneumatically-driven polymer right atrial and ventricular models with the pulmonary arterial valve chamber, silicone-made peripheral pulmonary artery model, and a venous reservoir. A woven polyester vascular graft and commercially available mechanical bileaflet valve were installed into the valve chamber. Then, the right ventricular pressure and pulmonary arterial pressure were regulated by the peripheral resistive unit. As a result, we successfully obtained the standard conditions of our mechanical circulatory system to be 28/3 (systolic/diastolic) mmHg of right ventricular pressure, 29/7 mmHg of pulmonary arterial pressure, 6 mmHg of mean right atrial pressure, and 3.0 L/min of pulmonary flow rate. To carry out the sophisticated assessment for the support of the pulmonary surgical and percutaneous treatments, we are preparing the next step with the reproduction of respiratory changes in pulmonary peripheral resistance, and the patient-specific shape vascular model including catheter access vessels. Under the highly simulated both pulmonary anatomical morphology and hemodynamic function conditions, effective preclinical examination of newly designed surgical or percutaneous pulmonary circulatory support devices can be performed.

Yusuke Tsuboko, Yasuyuki Shiraishi, Akihiro Yamada, Kiyotaka Iwasaki, Mitsuo Umezu, Tomoyuki Yambe

Healthcare Facilities—Emergency Preparedness Assessment and Training

Frontmatter

Education Successes Applied to Disaster Preparedness, Meeting Infectious Diseases and Malnutrition Challenges

Hurricanes, floods and earthquakes have devastated part of the Caribbean and Latin America Region: “Maria” hurricane in Puerto Rico, flooding disaster in Peru, the several serious earthquakes in Mexico, Colombia, Chile, Argentina, occurred recently; it is required to ensure the effective functioning of the health systems at the potential situation of an emergency. Natural disasters and other emergencies around the world put the populations at risk; they may cause diseases and/or the disruption of health systems, facilities and services. The health risks of a disaster can be mitigated by building capacities of individuals, community and the country with developed or developing economies to protect health, Preparedness should address all the health disciplines. Responding to the effects of climate change on 2017 the National Institute of Health of Peru trained health workers from the 6 regions seriously affected by dengue disease, the result improved the effectiveness of the regional laboratories through the on time distribution and correct use of supplies to respond to the emergency. On 2014, the Philippines trained to prepare health professionals working in hospitals to detect and safely manage Ebola virus disease (EVD): public, private and local government hospitals were engaged. The confidence in managing EVD increased significantly (P = 0.018) with 96% of participants feeling more prepared to safely manage EVD cases. In other country like Ethiopia the adequate preparedness in emergencies and disaster response improved the capacities and better understanding of context specific causes of acute malnutrition and contributed to prevent the increase of severe acute malnutrition in the Horn of Africa in 2011 and other places in 2013 and 2014.

R. Rivas, Y. David, T. Clark

The Valley of Death in Medical Technology Transfer Why It Exists and How to Cross It

Frontmatter

Experience from Industrial Graduate (PhD) Schools

Traditionally, research education is performed within the universities, and the PhD students are working within a research group. However, technical development and also research is performed within companies, and the need to keep up with the latest findings in research and to strengthen the competence within the private business sector is increasing. At Mälardalen University, we have experience from working in several Industrial Graduate Schools. The collaboration with the companies gets intensified and deepened trough such programmes, and the university tends to keep the good contact with previous PhD students and their companies also many years after their graduation. The Graduate Schools also give the companies good insight in the university world. Presently, we are involved in two Graduate Schools, and several of the PhD projects are focusing within Biomedical Engineering. Further, one of the graduate schools is linked to the research profile Embedded Sensor Systems for Health, which is supported from the same financier. Companies are involved also in the research profile, and through these activities, the Industrial PhD students form a critical mass and can exchange both experience and knowledge with other companies and with university researchers.

Maria Lindén, Mats Björkman

Women in Medical Physics and Biomedical Engineering

Frontmatter

Gender Balance in Medical Physics—Lost in Transition?

Before the toppling of the communist regime in Romania in 1989, the gender distribution in physics college students was bent towards males with an approximate two-thirds to one-third ratio. A recent statistical analysis made among researchers that have applied for research grants in the area of health science (including medical physics) shows that the number of male applicants is around double the number of female applicants. However, a look at the current gender balance among clinical medical physicists shows a clear bend towards females. Theoretically, this could result in an increased number of female researchers in medical physics, though practically this does not happen due to the large clinical workload in the Romanian hospitals which limits the time and effort necessary for scientific explorations. This fact leads us to the actual category of skilled people who undertake research: the academic staff. Among them, the gender balance is off, as the male to female ratio is nearing 3. Given these facts, it is interesting to think about the choices made by males and females after graduation, entering the workforce. Despite the general decline in science students over the last few decades, medical physics keeps being an attractive educational offer presented by several Romanian universities. An interesting shift is that among current medical physics students, the large majority are female both at undergraduate and postgraduate levels. Does this mean that in 20 years we will see a dominance of females in higher academic positions and research grant applications? Can we afford to just let nature take its course, or do we have to actively intervene to encourage women to choose an academic and research career after graduation?

Loredana G. Marcu, David Marcu

Crude Oil in Drinking Water: Chitosan Intervention

Water pollution affects drinking water from rivers, streams, lakes and oceans all over the world. In many developing countries, it is usually a leading cause of death by people drinking from polluted water.

Eileen E. C. Agoha

Women in Biomedical Engineering and Medical Physics in the Czech Republic

In last decades the effort to increase the number of women applying for studies at technical universities, and consequently for a job in the field of technology, can be seen in European countries. We analyzed the situation in the Czech Republic and found differences in ratio of females in individual engineering disciplines. We can see a positive trend in biomedical engineering and medical physics where the percentage of female students almost reached 50% in bachelor and master study. However, in PhD study and in research in general the number of females is lower. Successively, it is also lower in jobs in the health care sector. Although the jobs are on the border between engineering and life sciences, they are considered more as engineering jobs. And employment of women in any field of engineering is still considered nontraditional. We discuss the position of females as employees and present their potential advantage in biomedical engineering and medical physics jobs. As a potential support to professional development we propose mentoring and show its positive impact on personal and professional growth.

Lenka Lhotska

Emerging Technology in Diabetes Care Advances Real-Time Diabetes Monitoring Systems

Frontmatter

A Combined-Predictor Approach to Glycaemia Prediction for Type 1 Diabetes

Glycaemia prediction plays a vital role in preventing complications related to diabetes mellitus type 1, supporting physicians in their clinical decisions and motivating diabetics to improve their everyday life. Several algorithms, such as mathematical models or neural networks, have been proposed for blood glucose prediction. An approach of combining several glycaemia prediction models is proposed. The main idea of this framework is that the outcome of each prediction model becomes a new feature for a simple regressive model. This approach can be applied to combine any blood glycaemia prediction algorithms. As an example, the proposed method was used to combine an Autoregressive model with exogenous inputs, a Support Vector Regression model and an Extreme Learning Machine for regression model. The multiple-predictor was compared to these three prediction algorithms on the continuous glucose monitoring system and insulin pump readings of one type 1 diabetic patient for one month. The algorithms were evaluated in terms of root-mean-square error and Clarke error-grid analysis for 30, 45 and 60 min prediction horizons.

Kyriaki Saiti, Martin Macaš, Kateřina Štechová, Pavlína Pit’hová, Lenka Lhotská

Improving Prediction of Glycaemia Course After Different Meals—New Individualized Approach

Motivation and objectives: Diabetes is one of the biggest medical problems nowadays, having different forms and different mechanism of development but the ultimate result is the same—hyperglycaemia. Hyperglycaemia leads to development of chronic diabetic complications, which are the most frequent cause of worsening patient’s life quality and often shortening life expectancy. All diabetes mellitus (DM) type 1 patients and some of DM type 2 patients require full insulin substitution. It is not simple to adjust insulin dose to different meals and different daily activities. To help patients with this challenge we started to develop an application for smart phones having new features in comparison with existing applications. We concentrated on individual response to different types of meals (division based on glycaemic index), to physical activity and individually different basal metabolic rate. Material and methods: So far 24 patients, mostly insulin pump users, were enrolled. Patients used during the study at least 4 weeks RT-CGM and during this period they were asked to document all food and drinks containing carbohydrates by smart phone camera. Patients wrote during this time a detailed logbook as well. The detailed nutritional analysis of patient’s food was done as well as evaluation of other condition (level of depression, measurement of basal metabolic rate). Results: The quality of photos was problematic but the biggest problem was to analyze mixed meal from the photography. It was not possible without at least short patient’s description. Patient’s diet was unhealthy (high fat content etc.) and patients despite remedial nutritional reeducation made mistakes in carbohydrates counting which was reflected in their glycaemia profiles. Conclusion: It seems that using photos with brief notes is an acceptable solution and adding a personalized database of favourite meals with correct nutritional data (which we are developing now) may be very helpful. Then the patient only confirms selected meal and does not need to insert all data again. Based on data from the insulin pump and the glucose sensor and inserted information about the planned meal from the patient, the application can recommend the prandial bolus to be injected before meal.

Lenka Lhotska, Katerina Stechova, Jan Hlúbik

The Status of Bioengineering, Biomedical Engineering and Clinical Engineering Education in Latin America. “Curriculum, Accreditation, Innovation and Research”

Frontmatter

Innovative Biosensor of Circulating Breast Cancer Cells; a Potential Tool in Latin America Oncology Rooms

The detection of circulating tumoral cells represents the possibility for therapy monitoring as well as prevent metastasis in oncology patients. Portable and economical technologies are required in most of the oncology rooms of third level Latin America hospitals. In this work an innovative biosensor of circulating breast cancer cells on the basis of bioimpedance spectroscopy measurements assisted with magnetic nanoparticles is presented. The technical proposal involves a microfluidic system for cancer cells separation by immunomagnetic technique and its detection by multifrequency bioimpedance measurements. An experimental proof of concept to detect a typical breast cancer cell line was developed to evaluate the sensitivity of the system. The results shown the technical proposal feasibility as portable, inexpensive and non-invasive biosensor of circulating tumoral cells, as well as its technical feasibility for implementation in oncology rooms of Latin America third level hospitals.

César A. González, Herberth Bravo

Application of EM Field Medical Diagnostics

Frontmatter

Prototype of Simplified Microwave Imaging System for Brain Stroke Follow Up

Stroke could be detected by Microwave Imaging method (MWI) in the future. At ELEDIA@CTU laboratory was designed prototype of MWI system for stroke follow up/detection. The system was able to detect five from six strokes which were then reconstructed by existing algorithm for difference Microwave Imaging. These results were very valuable for next research where for example new antenna elements need to be design as well as realistic phantom of human head.

Jan Tesarik, Luis F. Diaz Rondon, Ondrej Fiser

Samples of Dry Head Tissues Phantoms for Brain Stroke Classification

Phantoms are necessarily for testing of MWI method. At ELEDIA@CTU laboratory phantom for testing of brain stroke classification are designing. For that purpose, new materials/substances were tested. It was prepared a few series of phantom samples with different weight percentages of given materials. Fabricated samples were measured by dielectric probe. Measured dielectric parameters shown that some of samples can mimic head tissues like skin, skull and CSF. Results of this contribution will be used for fabrication of dry heterogeneous human head phantom.

Jan Tesarik, Tomas Pokorny, Lukas Holek

High-Water Content Phantom for Microwave Imaging and Microwave Hyperthermia

The main goal of this contribution is the investigation, design, and evaluation of an agar-based high-water content phantom for microwave imaging and hyperthermia. The contribution attempts to specify preparing procedure to get the most uniform results and describes the problems during the fabrication of the phantom, solves the problem with air bubbles. The effect of the size of PE powder particles to dielectric properties (40–48 and 150 μm) was evaluated. Dielectric properties of agar phantoms with different compositions of grape sugar and polyethylene powder were compared for lowering the relative part of the complex permittivity over the frequency range of 10–2995 MHz. Proposed phantom also consists of agar powder, distilled water, sodium chloride and TX-151. The relative permittivity was decreased to the value under 60 at frequency 434 MHz for muscle phantom with available equipment and fabrication (with 13.23% PE powder, 40–48 μm).

Michaela Kantova, Ondrej Fiser, Ilja Merunka, Jan Vrba, Jan Tesarik

Processing of Standard MR Images Prior Execution of the MR-Based Electrical Properties Tomography (MREPT) Method

Magnetic resonance-based electrical properties tomography (MREPT), uses information of the $$ B_{1}^{ + } $$ field distribution in MRI, and computes electrical properties relative permittivity and electrical conductivity via the Helmholtz equation. The method can be done using standard MRI sequences, boosting the method into a more realistic clinical environment. MRI images need to undergo certain image pre-processing to correct ailments like noise and phase shifting. Recent publications on the topic report encouraging results and give a detailed explanation on the theory in which the process is based. However, little or none explanation is given to the processing to which the standard MRI images need to undergo in order for the method to be correctly implemented. Emphasis will be put on processing and corrections that needed to be applied to the retrieved MRI images to arrive to the results that are here reported.

Luis F. Díaz Rondón, Jan Tesarik

Metamaterial Sensor for Microwave Non-invasive Blood Glucose Monitoring

In our previous paper, a metamaterial and microstrip transmission line sensors for non-invasive blood glucose level monitoring were designed. In this paper two different models of dielectric properties of blood glucose solutions are used to evaluate sensors’ sensitivity by means of numerical simulations. Model A is adopted from professional literature and the model B was created by our group using information about dielectric properties of blood plasma-glucose solutions, recently published dielectric properties of red blood cell cytoplasm-glucose solutions and an electromagnetic mixing formula. Both sensors shows smaller sensitivity for the model B than for the model A. Due to non-linear dependency of dielectric properties on glucose concentration predicted by model B a lower sensitivity for high glucose concentrations was observed. The metamaterial sensor shows approximately 10-times higher sensitivity than the microstrip sensor of the same length.

Jan Vrba, David Vrba, Luis Díaz, Ondřej Fišer

Intelligent Methods and Modeling in the Biomedical Engineering

Frontmatter

A New Numerical Model of the Intra-aortic Balloon Pump as a Tool for Clinical Simulation and Outcome Prediction

Counterpulsation is the form of circulatory support provided by the intra-aortic balloon pump (IABP), a device widely used in the clinical setting to assist the left ventricle by mechanical control of blood volume displacement within the aorta. The principles underlying the IABP function are well established but the interactions with the cardiovascular system make its performance rather complicated and still not completely understood. Here we propose a novel IABP numerical model as a tool with potential for clinical application in terms of simulation and outcome prediction in critical patients. The analysis of IABP assistance is presented in terms of the effects on stroke volume, mean aortic diastolic pressure, aortic end-systolic pressure, aortic end-diastolic pressure, endocardial viability ratio and pressure-volume loop shift. Balloon inflation/deflation rate and timing are also considered. The new model was implemented in CARDIOSIM© software simulator of the cardiovascular system.

Silvia Marconi, Carla Cappelli, Massimo Capoccia, Domenico M. Pisanelli, Igino Genuini, Claudio De Lazzari

Proposal of Electrode for Measuring Glucose Concentration in Blood

The article deals with the design of the electrode system and the appropriate measuring circuit for the measurement of blood glucose concentration, since the determination of the level of blood glucose is an integral part of many medical procedures for determining the state of the human organism. The aim of the concept is to create two functional devices with different design of the electrode system and to perform a series of measurements to verify the functionality and the data statistically process. There was used the principle of resistive sensing of non-electric quantities, so the designed systems using gold electrodes working as electrolytic sensors. The problem relating to the measuring circuit, which is the same for both electrode systems, has been solved by a microampere meter which can convert the generated signal to a suitable measured electrical signal. The signal is formed by the reaction of glucose and enzyme, the resulting value being directly proportional to the glucose concentration. At this work, created systems fully meet specified conditions and requirements. The research confirmed the functionality of the designed units. On the basis of obtained data is possible to compare and evaluate the constructed electrode systems and to make the basis for further development in the subject matter.

Klara Fiedorova, Martin Augustynek, Tomas Klinkovsky

Evaluation Application for Tracking and Statistical Analysis of Patient Data from Hospital Real Time Location System

In the recent time, an importance of the Real-time Locating systems (RTLS) in the hospital environment is increasingly important. Such systems are essentially utilized for the localization of either unmovable objects, or patients in the hospital environment. It is supposed that patients who underwent some trauma and surgery may have influenced their cognitive functions in a sense of lost concentration, and orientation is space. Such disorders may endanger the patient’s health. In cooperation with the Trauma Center of University Hospital we have designed a localization system constituting the patients IR tags which are detected by the IR anchors placed in every hospital room. Data from such system represents the patient’s movement and localization completed by sophisticated system of alarms. In this context we have developed the SW application which is connected with the RTLS database where the patient’s localization data are stored. This application is fully integrated into the RTLS system. The SW application evaluates time data represents spent time in every room. The patient’s data are consecutively refreshed and updated in the SW application to receive current information.

David Oczka, Marek Penhaker, Lukáš Knybel, Jan Kubíček

Baby Cry Recognition Using Deep Neural Networks

Infant cry recognition is a challenging task as it is hard to determine the speech features that can allow researchers to clearly separate between different types of cries. However, baby cry is treated as a different way of communication of speech. The types of baby cry can be differentiated using Mel-Frequency Cepstral Coefficient (MFCC) with appropriate artificial intelligence model. Stacked restricted Boltzmann machine (RBN) is popular in providing few layers of neural networks to convert the high dimensional data to lower dimensional data to fine tune the input data to a better initialized weight for the neural networks. Usually RBN is used with another deep neural network to form the deep belief networks (DBN), and the studies in this direction is heading towards the convolutional-RBN variant. The study on RBN to pre-train Convolutional neural networks (CNN) without convolution function in the RBN meanwhile is scarce due to the Back propagation and principal component analysis can be applied directly to the CNN. In this paper, we describe the hybrid system between RBN and CNN for learning class specific features for baby cry recognition using the feature of Mel-Frequency Cepstral Coefficient. We archived an 78.6% of accuracy on 5 types of baby cries by validating the proposed model on baby cry recognition.

Boon Fei Yong, Hua Nong Ting, Kwan Hoong Ng

Clinical Engineering Innovation Leading to Improved Clinical Outcomes

Frontmatter

Healthcare Technology Management (HTM) by Japanese Clinical Engineers: The Importance of CEs in Hospitals in Japan

Japanese clinical engineer (CE) is a significant and unique profession compared with other nations with its dual clinical and technology focus and national licensing. The CE system of licensing was established in May 1987 under the Clinical Engineers Act. CEs are required to complete 3 to 4 years in designated schools and pass a national examination. It is a professional medical position responsible for the operation and maintenance of life-support and non-life-support medical device systems under the direction of physicians. In Japan, CEs support and operate various life-support medical devices. Technology developments have led to significant improvements in performance, making devices easier to break and requiring specialized maintenance. Some of our healthcare technology management (HTM) initiatives include: 1. Rental equipment: oversee use and conduct in-house testing and repair, avoiding faulty units. 2. Ventilator maintenance: a multi-year track record of assessing and replacing defective parts in-house, contributing to prompt repairs and reduced costs. 3. Battery-equipped devices: created a more efficient system for charge management. 4. Intermittent pneumatic compression device dedicated tester: reducing the incidence of thromboses and embolism in patients.

Jun Yoshioka, Keiko Fukuta, Hiroki Igeta, Takeshi Ifuku, Takashi Honma

Partial Findings of the Clinical Engineering Body of Knowledge and Body of Practice Survey

Clinical Engineering has been fundamental to health care for decades, providing expertise in the interaction between medical devices and the health care system. Because the skills and activities required from clinical engineers around the world are not homogeneous, the Clinical Engineering Division at IFMBE decided to promote a global survey to identify the body of knowledge and body of practices they adopt. The survey was aimed at collecting data about employers and professional status, background knowledge, activity responsibilities, and the time spent in the multiple classes of activities. Survey results suggest the profession is still associated to certain traditional characteristics, such as the predominance of professionals with background in electrical, electronic, or mechanical engineering and the prevalence of hospitals and clinics as employers. The questionnaire seems adequate to reveal which skills and activities are considered the most relevant by clinical engineers, but more responses are required before a solid Body of Knowledge and Body of Practice can be defined.

S. J. Calil, L. N. Nascimento

Global Clinical Engineering Innovation, Overview and New Perspectives

Health Technology (HT) is vital to health care and wellness programs. The dependence on HT services and the expectation for novel approaches has never been greater. Patients, payers, and administrators are demanding innovative HT and optimal services. Clinical Engineers (CEs) are critical members of the healthcare team and are responsible for current and emerging strategies for HT management. But is their role recognized? An IFMBE Clinical Engineering Division (CED) survey determined it was generally unrecognized and collected further data with a landmark survey of success stories. 400 stories from 125 countries qualified as evidence-based CE contributions. A subset of innovation stories were subsequently extracted to see how innovation approaches and solutions could be effectively shared with stakeholders. These stories demonstrated significant benefits from HT innovation and evidenced a compelling case for CEs to embrace innovation as brand for their work and a path to enhance recognition within the global health community.

Mario Castañeda, Thomas Judd

Recent Advances in EEG Signal Processing

Frontmatter

Feature Extraction and Visualization of MI-EEG with L-MVU Algorithm

The feature extraction of Motor Imagery Electroencephalography (MI-EEG), as a key technique of brain computer interface system, has attracted increasing attention in recent years. Because of the high temporal resolution of MI-EEG, researchers are usually bedeviled by the curse of dimensionality. Some manifold learning approaches, such as Isometric Mapping (ISOMAP) and Local Linear Embedding (LLE) etc., have been applied to dimension reduction of MI-EEG by modeling the nonlinear intrinsic structure embedded in the original high-dimensional data. However, these methods are difficulty to exactly represent the nonlinear manifold, affecting the classification accuracy. The Maximum Variance Unfolding (MVU) can solve this problem, but it is unsuitable for online application due to the computation complexity. In this paper, a novel feature extraction approach is proposed based on the Landmark version of Maximum Variance Unfolding (L-MVU). First, the MI-EEG signals are preprocessed according to the event-related desynchronization (ERD) and event-related synchronization (ERS). Then, L-MVU is used to extract the nonlinear features, and a joint optimization of parameters is performed by using the traversing method. Finally, a back-propagation neural network is selected to classify the features. Based on a public dataset, some experiments are conducted, and the experiment results show that L-MVU can preserve more information and perfectly extract the nonlinear nature of original MI-EEG, and reduce the redundant and irrelevant information by introducing the landmark points as well, yielding a higher classification accuracy and a lower computation cost. Furthermore, the proposed method has a better effect on feature visualization with an obvious clustering distribution.

Ming-ai Li, Hong-wei Xi, Yan-jun Sun

Influence of Parameter Choice on the Detection of High-Dimensional Functional Networks

The detection of directed interactions within networks derived from spatially highly resolved data, such as functional magnetic resonance imaging (fMRI) has been a challenging task for the last years. Commonly this is solved by restricting the analysis to a small number of representative network nodes (e.g. fMRI voxels), to regions of interest (e.g. brain areas) or by using dimension reduction methods like principal or independent component analysis. Recently, these problems have successfully been encountered by combining multivariate autoregressive models and parallel factor analysis. This approach involves a cascade of analysis steps, entailing a number of parameters that have to be chosen carefully. Yet, the question of an appropriate choice of analysis parameters has not been clarified so far—in particular for temporally varying models. In this work we fill this gap. Synthetic data with known underlying ground truth structure are generated to evaluate the correctness of results in dependence on the parameter choice. Resting state fMRI data are used to assess the influence of the involved parameters in the clinical application. We found that model residuals offer a good means for determining appropriate filter algorithm parameters; the model order should be chosen according to two aspects: the well-established information criteria and the fit between Fourier and estimated spectra.

Britta Pester, Karl-Jürgen Bär, Lutz Leistritz

Embedded Sensor Systems for Health Technology Applications at Home and at Work

Frontmatter

Extraction of Diagnostic Information from Phonocardiographic Signal Using Time-Growing Neural Network

This paper presents an original method for extracting medical information from a heart sound recording, so called Phonocardiographic (PCG) signal. The extracted information is employed by a binary classifier to distinguish between stenosis and regurgitation murmurs. The method is based on using our original neural network, the Time-Growing Neural Network (TGNN), in an innovative way. Children with an obstruction on their semilunar valve are considered as the patient group (PG) against a reference group (RG) of children with a regurgitation in their atrioventricular valve. PCG signals were collected from 55 children, 25/30 from the PG/RG, who referred to the Children Medical Center of Tehran University. The study was conducted according to the guidelines of Good Clinical Practices and the Declaration of Helsinki. Informed consents were obtained for all the patients prior to the data acquisition. The accuracy and sensitivity of the method was estimated to be 85% and 80% respectively, exhibiting a very good performance to be used as a part of decision support system. Such a decision support system can improve the screening accuracy in primary healthcare centers, thanks to the innovative use of TGNN.

Arash Gharehbaghi, Ankica Babic, Amir A. Sepehri

Physiological Data Monitoring of Members of Air Forces During Training on Simulators

Many complex situations can be induced to the members of air forces during training on simulators, which may result in mentally vigorous situations or even overload. The aim of the paper is to describe the current state and our contribution to development of systems for measurement of the physiological data of basic member of air force including mission commander, pilots, air traffic controllers and ground support staff. The reason for physiological data monitoring is to test the possibility of usage them to estimate the physical and psychological state of the team members. The base for the design of physiological data monitoring was the FlexiGuar system, originally developed at the FBMI CTU. The core of simulators for training of military personnel in aviation was Lockheed Martin’s Prepar3D simulation software. Two airplane cockpits were used as simulators for training of two pilots, air traffic control simulator, i.e. a control tower simulator, and an airport ground station for the preparation of aviation ground staff. The proposed systems are used for simultaneous measurement of the working performance and physiological data of members of the four‐member team during their training. The physiological data, heart rate, body temperature, movement activity and perspiration intensity, are transferred to the commander visualization unit for further evaluation. Designed systems and methods could help to monitor, on the base of physiological data and data from simulators, the stress load of team members.

Jiri Kacer, Vaclav Krivanek, Ludek Cicmanec, Patrik Kutilek, Jan Farlik, Jan Hejda, Slavka Viteckova, Petr Volf, Karel Hana, Pavel Smrcka

Application of Smart Sock System for Testing of Shoe Cushioning Properties

Appropriate choice of shoes with required cushioning characteristics is rather an urgent problem for people from very different groups, such as sportsmen, elderly people, people with foot disorders and locomotion problems. Present research is devoted to further development of wireless DAids™ Pressure Sock System and its application for shoe cushioning estimation. In particular, a new version of pressure sensors with improved sensitivity and working range is designed and tested. Based on above-mentioned developments, the possibility of shoe cushioning testing using DAid™ Pressure Sock System was studied. For this purpose, gait records of several test subjects who used sets of shoes with different cushioning properties, as well as bare walking, were made. Data analysis showed that the developed system gives the possibility to recognize different shoe cushioning. Several approaches to data processing to increase the sensitivity of such recognition are discussed. The comparison showed the potential ability of the developed system to test wirelessly shoe cushioning in real outdoor conditions. Such ability also provides the possibility to monitor and estimate degradation of cushioning quality of shoes under deterioration and environment.

Alexander Oks, Alexei Katashev, Peteris Eizentals, Zane Pavare, Darta Balcuna

Wireless Assistance System During Episodes of Freezing of Gait by Means Superficial Electrical Stimulation

Parkinson’s disease in an advanced stage presents the symptom of freezing of gait, approximately 80% of patients may have a freeze after 17 years of illness, provoking falls and injuries in the 60% of them, the medication is obsolete before this symptom. In search of new methodologies and instruments to help improve the lifestyle of these patients, a non-invasive wireless system is proposed to detect freezing and restart walking by means of superficial electrical stimulation during an episode. A sensor based on a triaxial accelerometer placed on the posterior secondary nerve was used to acquire and store the data of the right lower extremity during the presence of a freezing episode. The data was processed on a smartphone with Android operative system using the tool of discrete wavelet transform developed in Java. The transcutaneous electrical stimulation is applied near the posterior tibial nerve of the lower extremities to continue the walk, which presents better results compared to the vibratory stimulation presented in an earlier version from the authors. The results show feasible diagnostic tests for the validation of the system, such as precision, sensitivity and specificity.

B. Barzallo, C. Punin, C. Llumiguano, M. Huerta

Practical Performance Assessment of Dry Electrodes Under Skin Moisture for Wearable Long-Term Cardiac Rhythm Monitoring Systems

The use of wearable dry sensors for long term recordings of electrocardiographic bipolar leads located in comfortable areas of the body, is a requirement for detecting certain heart rhythms. Knowledge of the skin-electrode electrical performance of dry electrodes is necessary when seeking to improve various processing stages for signal quality enhancement. In this paper, methods for the assessment of skin-electrode impedance (Zse) of dry electrodes and its modelling are presented. We need to know the behavior of dry electrodes when they are moistened with skin sweat, either at the time of exercise or when it comes to warm climates, under the following posed hypothesis: the impedance magnitude of dry electrodes under study would be significantly lower after they have been moistened with sweat, and comparatively could reach levels of impedance characteristics presented by standard pre-gelled ECG electrodes. Measurements were carried out on selected dry-electrode materials such as silver, stainless steel, AgCl (dry), polyurethane and iron (Fe). These presented, |Zse| values between 500 kΩ and 1 MΩ within the main ECG frequency range (1–100 Hz), under no sweat conditions, and values of few kiloohms under artificial sweat conditions. However, in spite of the sweat conditions, open bandwidth ECG traces were of similar quality and stability, within tolerance; with dry AgCl electrode material presenting the best ECG trace performance.

Antonio Bosnjak, Omar J. Escalona

Integrated Precision Medicine Technologies

Frontmatter

A Multimodal Machine Learning Approach to Omics-Based Risk Stratification in Coronary Artery Disease

This study aims at developing a personalized model for coronary artery disease (CAD) risk stratification based on machine learning modelling of non-imaging data, i.e. clinical, molecular, cellular, inflammatory, and omics data. A multimodal architectural approach is proposed whose generalization capability, with respect to CAD stratification, is currently evaluated. Different data fusion techniques are investigated, ranging from early to late integration methods, aiming at designing a predictive model capable of representing genotype-phenotype interactions pertaining to CAD development. An initial evaluation of the discriminative capacity of the feature space with respect to a binary classification problem (No CAD, CAD), although not complete, shows that: (i) kernel-based classification provides more accurate results as compared with neural network-based and decision tree-based modelling, and (ii) appropriate input refinement by feature ranking has the potential to increase the sensitivity of the model.

Eleni I. Georga, Nikolaos S. Tachos, Antonis I. Sakellarios, Gualtiero Pelosi, Silvia Rocchiccioli, Oberdan Parodi, Lampros K. Michalis, Dimitrios I. Fotiadis

Backmatter

Weitere Informationen