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In Morocco, the radiation doses received by adult patients are increasing due to the number of CT examinations performed and the larger number of computed tomography (CT) scanners installed. The aim of this study was to evaluate the radiation doses received by patients for the most common adult CT examinations in order to establish local diagnostic reference levels (DRLs). Data from 1016 adult patients were collected during 3 months from four Moroccan hospitals. Dose length product (DLP) and volumetric computed tomography dose index (CTDIvol) were evaluated by determining the 75th percentile as diagnostic reference levels for the most common examinations including head, chest and abdomen. The DRL for each examination was compared with other studies. The established DRLs in Morocco in terms of CTDIvol were 57.4, 12.3 and 10.9 for CT examinations of the head, chest, abdomen, respectively. For DLP, they were 1020, 632 and 714, respectively. These established DRLs for CTDIvol were almost similar to the UK DRLs at all examinations, higher than the Egyptian DRLs and lower than the Japanese DRLs at the head CT examination, lower than the DRLs from Egypt and Japan at the CT abdomen examination. In terms of DLP, the DRLs were higher than those of the British studies, lower than those of the Egyptian and Japanese studies at the head CT examination were higher at chest CT and lower at abdominal CT than those of all selected studies. The higher level of established DRLs in our study demonstrates the requirement of an optimization process while keeping a good image quality for a reliable diagnosis.

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In Morocco, the radiation protection of patients undergoing medical imaging examinations using ionizing radiation sources is now governed by specific provisions of Chapter VII of Law no142-12 (Loi no142-12 – AMSSNuR, 2015). The principle of justification of procedures and the principle of optimization of doses delivered constitute the basis of the legislation governing medical exposure. DRLs are considered as an important optimization tool encouraging healthcare professionals to optimize their practice and assure a better patient safety. In this survey, Local Diagnostic Reference Levels (LDRLs) were established for the eight most frequent examinations in Morocco. Data from 1747 patients were collected from seven regional hospitals. The proposed LDRLs were defined as the 75th percentile of the mean entrance surface dose distribution (ESD) in mGy using the indirect dosimetry method according to the IAEA Report Series No. 457. The LDRLs values reported in this study were for the eight examinations: skull (PA) 2.8 mGy, chest (PA) 0.51 mGy, abdomen (AP) 7.6 mGy, pelvis (AP) 6.45 mGy, lumbar (AP) 7.8 mGy, lumbar (Lat) 10.7 mGy, cervical (AP) 2.2 mGy, and cervical (Lat) 2.4 mGy. The DRLs reported in Morocco were compared with those of international authorities and other countries: IRSN (France), NRPB (UK), Japan, Sudan, and Iran. The present work assesses the local DRLs in Morocco and constitutes a starting point that will provide professionals with a tool to help them optimize the doses delivered to patients. Furthermore, the definition of national DRLs by radiography is an essential step in the process of optimizing medical exposures.

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