3rd International Conference on Radiation Safety & Security in Healthcare Services

Computed tomography (CT) is mainly associated with high radiation dose exposure to patient and potential for increased risk of cancer. The increasing number of CT head examinations worldwide shows the need for optimization and strategy for dose reduction technique. Thus, the aim of this study is to evaluate the influence of pitch factor in reducing CT dose particularly CT head examination. In this study, the scan acquisition parameter and the CT dose parametric information were collected retrospectively from 16-slice CT scanner (Toshiba Activion) console display. Effective dose (E) was estimated using effective dose per dose-length product (E/DLP) conversion factor, k = 0.0021 mSv/mGy.cm. This experiment involved two sets of study, the pre-intervention (n = 163, 58 ± 18 years, 120 kV, 200 mAs, pitch = 0.688) and post-intervention (n = 165, 57 ± 19 years, 120 kV, 200 mAs, pitch = 0.938) on January 2017 and March 2017, respectively. The mean CTDI_vol values recorded for pre- and post-intervention were 70.00 ± 8.84 mGy and 51.30 ± 0.72 mGy, respectively. Generally, the mean E value for pre-intervention and post-intervention were 2.75 ± 0.35 mSv and 2.16 ± 0.17 mSv, respectively. It is interesting to note that by increasing the pitch factor in CT head examination has significantly reduced the CT head dose exposure without adversely affecting image quality. The mean DLP value for post-intervention is 1030.10 mGy.cm and has been set as institutional DRL. In conclusion, it is recommended for radiology personnel especially radiographer and radiologist to be aware certain acquisition parameters i.e. pitch factor that work for the optimization process.

This main goal of this study was to evaluate image quality in single-energy (SE) and dual-energy (DE) CT imaging with the presence of barium and iodine. A fabricated polymethyl methacrylate abdomen phantom with 32 cm diameter size was used to mimic human abdomen. Two different contrast agents: barium and iodine, were scanned separately. The imaging parameters for SECT were set at tube voltage 80, 120 and 140 kV while the imaging parameters for DECT were set at fixed tube voltage 80/140 kV. Both scan modes were set at the different pitch: 0.6 and 1.0 mm, and the slice thickness was set at 3.0 and 5.0 mm with automatic exposure control for the tube current. The CT images obtained from both scanning were analysed to evaluate the signal-to-noise ratio (SNR). Barium and iodine gave highest SNR of 39.30 and 182.68, respectively, at a tube voltage of 140 kV, a pitch of 1 and a slice thickness of 3 mm for SECT. In DECT mode, the highest SNR for barium and iodine were 36.74 and 112.15 respectively at pitch 1 and slice thickness of 3 mm. There was no significant difference between SNR of barium and iodine obtained with both CT imaging modes with p-values of 0.75 and 0.12, respectively.

The CT dose index (CTDI) and dose length product (DLP) are the most frequently used indicators to represent radiation doses in CT examination. However, the limitation of both is that they only estimate dose based on the scanner output information for specific standardized condition and phantom sizes. This study was aimed in evaluation of the radiation dose based on the SSDE method for adult abdomen CT study at AMDI, Universiti Sains Malaysia, Penang. A total of 91 CT procedures were selected consisting only adult patients undergo CT thorax-abdomen-pelvis (TAP) examination. As recommended by American Association of Physicist in Medicine (AAPM), the individual dimensions of each patient were determined. The conversion factors for SSDE were multiplied with the displayed CTDI_vol. The comparative study between displayed CTDI_vol with SSDE-calculated dose were done and percentage difference were then determined. From the results, significant differences were observed between SSDE-calculated and displayed dose with variations of 3–47% for method of AP and LAT summation, and 1.96–46% with method of effective diameter. The SSDE calculated doses were significantly higher than the displayed dose values by CT scanner. Therefore, evaluation of patient dose by individual specific size is critical for optimization of radiation exposure in CT imaging.

Patient exposure from digital dental radiography has increased rapidly and contributes to one of the major sources for radiation doses received in diagnostic radiology. Therefore, assessment on patient dose is crucially important for dose optimisation and justification. However, there are currently no national diagnostic reference level (NDRL) has been established in Malaysia for dental radiography. This study was aimed to evaluate the patient doses received from digital dental radiography which includes orthopantomogram (OPG), cone beam computed tomography (CBCT), and cephalometric examinations at Advanced Medical and Dental Institute (AMDI), Malaysia and serves as preliminary work in establishment of local DRL. The data of dose-area product (DAP) values for all dental examinations performed were gathered started from May 2015 until March 2017. For comparative study, the third quartiles for each examination were determined and compared with the international DRL. A total of 684 cases, consisting of OPG (67%), CBCT (6%), and cephalometric examinations (27%) performed during that period. The DAP values were ranged between 47.4 and 363.2 mGy cm² for OPG, 392.4 and 1254.4 mGy cm² for CBCT, and 17.4 and 33.3 mGy cm² for cephalometric procedure. From the results, it showed that patient dose mainly depends on image acquisition protocol. Patient dose assessment is significant for radiation protection management in clinical practice.

Artifacts arising from metallic implant had been a concern for Computed Tomography (CT) imaging in obtaining optimal image quality. The main aim of this study was to evaluate the metal artifacts severity from two different types of orthopedics screw and to optimise CT imaging parameters for metallic implants. A water-based abdomen phantom of diameter 32 cm (adult body size) was fabricated using polymethyl methacrylate (PMMA) materials. The fabricated phantom was scanned with dual-energy CT at 80 and 140 kV, and single-energy CT at 120 kV. Two types of orthopedic screws; titanium alloy (grade 5) and stainless steel (grade 316L) was used in this study. A phantom with orthopedics metal screw was scanned at various pitch (0.35, 0.60, 1.20) and slice thickness of 1.0, 3.0, 5.0 mm. The tube current was applied automatically using tube current modulation. In this phantom study, the severity of stainless steel and titanium alloy was analysed. Results showed that the signal-to-noise ratio (SNR) of titanium alloy was higher than the SNR of stainless steel. The optimal image quality of metallic implant was obtained at imaging parameters of pitch at 0.60 and 5.0 mm slice thickness. The use of optimum CT imaging parameters for orthopedic screw resulted in an improved CT image, as the SNR increases. This finding proves that optimum CT imaging parameters are able to reduce the metal artifacts severity on CT images. Therefore, it has potential for improving diagnostic performance in patients with severe metallic artifacts.

Personnel dose monitoring among nuclear medicine worker is the most vital component in the occupational safety. Generally, most of these workers are monitored by using variable type of personnel dosimeter such as optically stimulated luminescence (OSL), radio-photoluminescence (RPL), thermoluminescence dosimeter (TLD) and film badge. Therefore, we aimed to estimate whole body exposure of workers using OSL and RPL and evaluate the performance of both dosimeters in occupational dosimetry. 22 subjects (5 physicists, 6 pharmacists and 11 technologists) were participated in this study where both dosimeter was placed on mid-chest area for a period of 3 month. For analysis purpose, the RPL was sent to APM Nuclear Technology while OSL was analyzed by in house physicist using OSL reader (Microstar, Japan). Mean dose value Hp(10) of the nuclear medicine worker using OSL and RPL result obtained were 0.23 ± 0.11 mSv and 0.19 ± 0.07 mSv, respectively. As indicate from the result, there was a significant difference of dose between OSL and RPL. The range of dose value recorded for OSL and RPL measurement was 0.20 mSv to 0.26 mSv and 0.17 mSv to 0.21 mSv, respectively. The finding of this study shows that OSL was much more sensitive than RPL by a factor of 1.2. Therefore, OSL will enhance occupational safety program by minimizing radiation risk among radiation worker.

The main goal of this study was to determine the mass attenuation coefficient of paraffin wax and sodium chloride as tissue equivalent materials in medical imaging. In this study, a series of attenuation coefficient was evaluated for a mixture of paraffin wax and NaCl to be established as tissue equivalent materials. Five samples with difference paraffin-to-NaCl ratio were prepared. The attenuation coefficient of each sample was evaluated within energy range of 0.662 and 1.33 MeV. The measurements were performed with a NaI(Tl) detector for gamma spectrometry. The attenuation coefficient values obtained from this experiment were compared with mass attenuation coefficient obtained from the XCOM software and ICRU Report 44. The mass attenuation coefficients of the selected sample and human soft tissue are 0.151 cm²/g and 0.149 cm²/g respectively at energy of 150 keV. A sample with 25% of NaCl used was selected as an ideal tissue-equivalent material in this study.

Ministry of Health has joined the program of the Regional Security of Radioactive Sources (RSRS) to improve the Physical Protection and Security Management (PPSM) system of radioactive sources in medical institutions in Malaysia. This study is aimed to identify the compatibility of PPSM system components, used in medical institutions in Malaysia based on documents from the IAEA as well as to evaluate the effectiveness of its execution. Universiti Kebangsaan Malaysia Medical Centre, Ampang Hospital, Universiti Sains Malaysia Hospital, Advanced Medical and Dental Institute and Gleneagles Intan Medical Centre was chosen as a location for research. The system was assessed through questionnaires, interviews, observations and document review. From the results, it shows the effectiveness of implementing PPSM system still at a moderate level in all medical institutions in Malaysia. Improvements can be made through collaboration with the ministry and the management of medical institutions in which several components in the PPSM system has been identified as the details of the source of radioactive material, the security plan and security functions as well as to provide exposure to the employees by continuously organizing extensive courses, seminars and workshops.