ESTABLISHMENT OF A DIAGNOSTIC REFERENCE LEVEL FOR BRAIN CT PROCEDURES IN MOROCCAN HOSPITALS.

Purpose: The aim of this study is to evaluate the patient doses during ComputedTomography (CT) brain procedures in order to establish a local diagnostic reference level (DRL) in some hospitals in Morocco. Materials and methods: This study consisted of examining a total of 146 patients in six radiology departments in Morocco. The data were collected from CT Brain examinations at least of 20 CT scans per hospital. For each examination reported, CT acquisition parameters have included number of series, use of contrast medium, tube kV, tube current and rotation time, slice thickness, the displayed CT dose index (CTDIvol) and the Dose Length Product (DLP). Results: The patients were examined with their own department protocol using multislice CT (MSCT) quadruple slice, 16 and 64 CT slice from different manufacturers. The tube current time produce isusedin two hospitals (H4-AGA-CNSS, H5-RAB-INO). The patients are exposed to a high dose up 200 mAs. One hospital uses a higher value up to 130 kV per CT brain. The tube tension defines penetration strength of the X ray beam. In terms of DLP, the average dose varies between 379,4 mGy.cm and 2434 mGy.cm. Therefore, a third quartile value of 1408 mGy.cm can be used as a first DRL local for CT brain procedure for adults. The DRL value found is higher than that found in other countries. It is 14% to 42 % higher compared to other studies. This value is as a preliminary study result, initiated to raise the attention concerning the prevention of unnecessary radiation dose for patients in CT imaging. Conclusion: Doses received by patient during CT procedures vary from a radiology service to another and even at the same service. This large variation is due to patient clinical indication, CT system modality and image acquisition parameters. The value of 1408 mGy.cm assessed as the first Moroccan DRL for CT brain procedure for adults is the highest value found so far in theliterature. Therefore, in order to reduce this dose, corrective measures are required to eliminate unnecessary radiation dose that doesn?t contribute to the overall profile of the patients. So, we recommend the normalisation of practices in the radiology departments by the development of such protocols and the promotion of educational and training programs in the field of radioprotection of patients.