The large use of Computed Tomography Scan (CT scan) is a principal cause of increasing medical ionizing radiation exposure. Children are considered a population at risk for the occurrence of radiation-induced pathologies, and the implementation of radiation protection measures relies on the knowledge and skills of healthcare professionals. This analytical cross-sectional study aimed to assess the knowledge of Moroccan physicians prescribing pediatric CT scan examinations on the radiation protection of patients, radiation doses, and potential health risks of radiation exposure from CT scan. A questionnaire was distributed to all clinicians on the medical staff who prescribe pediatric CT examinations in five Moroccan pediatric hospitals. The questions have a focusing on prescribers’ practices and their knowledge of patient radiation protection, radiation doses, the potential health risks of radiation exposure from CT scan, and training on radiation protection. One hundred and ninety-two questionnaires were submitted to prescribers and among them, 88% responded. The data were analyzed using the Statistical Package of Microsoft Office Excel. Knowledge gaps regarding CT scan radiation doses and associated health risks among Moroccan physicians are evident from this study results, initial and continuing training of health care staff and the implementation of referral guidelines for medical imaging could lead to improve practitioners’ knowledge of patient radiation protection.

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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.

During Computed Tomography (CT) scan examinations, it is important to ensure a good diagnosis by providing the maximum information to detect pathologies and this can be done with a reduced dose. In this respect, several methods of dose reduction have been studied and evaluated. This work investigates the effect of tube voltage while varying the tube current on image quality and radiation dose at Chest CT examination. This study was conducted on HITACHI CT 16 slice Scanner using two phantoms for evaluating the dose and image quality; a PMMA phantom and a CATPHAN 500. Two tube voltages of 120 KVp and 100 KVp have been used for some variation of the tube currents (mAs) and recording the values of the measured quantities (CTDIv, spatial resolution, contrast to noise ratio CNR and noise). The scanning with 100 KVp at Chest CT examination led to a reduction in CTDIv until 45 %, an increase of noise from 17 % to 45 %, and the Spatial Resolution fell slightly (6 and 7 pl/cm) compared to the 120 KVp. The CNR shows a slight regression from 11 to 22 % for the 120 KVp and 100 KVp. This study has shown that despite the increase in the image noise at low tube voltage 100 KVp, it is possible to reduce the radiation dose by up to 45 % without degradation of image quality at Chest CT examination. Further works will evaluate the effect of acquisition parameters in other CT examinations.

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.