Detailed CT Dosimetry in 4 Moroccan Hospitals as a Preparation for the Development of National DRLs

Document Type : Original Paper


1 Laboratory of high energy physics Modelisation Simulation, Faculty of Sciences, University Mohammed V, Rabat, Morocco.

2 Hassan First University of Settat, High Institute of Health Sciences, Laboratory of Sciences and Health Technologies, Settat, Morocco

3 KU Leuven, Faculty of Medicine, Department of Imaging and Pathology, Medical Physics and Quality Assessment, Belgium.

4 Universitair Ziekenhuis Leuven

5 UZ Leuven · Department of Radiology, Belgium.

6 Associazione Italiana di Fisica Medica (AIFM), Milan, Italy


Introduction: Diagnostic reference levels (DRLs) can prevent excessive, unnecessary radiation exposure to patients and reduce the dose variation during different practices. This study aims to establish local DRLs for computed tomography (CT) procedures corresponding to Head, Chest, and Abdomen-Pelvis examinations (single acquisition) in Moroccan hospitals.
Material and Methods: A total of 1917 diagnostic CT examinations were included in this study: head, chest, abdomen–pelvis, lumbar, cervical, chest-abdomen–pelvis (CAP), and scanopelvimetry. Firstly, we analyzed the CT dose indicators in terms of the Volume computed tomography dose index (CTDIvol) and the dose length product (DLP) of all the examinations collected. Local diagnostic reference levels were proposed just for the head, thorax, and abdomen-pelvis due to the lack of data for the other examinations. Furthermore, we calculated the effective dose for chest examination using CT-expo software to estimate the effective and organ dose for chest CT.
Results: The estimated local DRLs expressed as the 3rd quartile using CTDIvol were 48 mGy, 14 mGy, and 12 mGy for the head, chest, and abdomen-pelvis, respectively, and 986, 496, and 651 for DLP, respectively.  Moreover, the proposed average effective dose for chest CT examinations was 6,3 mSv.
Conclusion: This work establishes local DRLs for CTDIvol and total DLP for head, chest, and abdomen-pelvis procedures and proposes effective doses for chest CT examinations in adult patients. The study shows that the results are conforming to the literature.


Main Subjects

  1. EUROSTAT, Statistics Explained. Healthcare resource statistics-technical resources and medical technology, Data extracted in August 2020. Available from:
  2. Brenner DJ. Slowing the increase in the population dose resulting from CT scans. Radiation research. 2010 Dec;174(6b):809-15.
  3. Bosch de Basea M, Salotti JA, Pearce MS, Muchart J, Riera L, Barber I, et al. Trends and patterns in the use of computed tomography in children and young adults in Catalonia—results from the EPI-CT study. Pediatric Radiology. 2016 Jan;46(1):119-29.
  4. Brenner DJ, Hall EJ. Computed tomography—an increasing source of radiation exposure. N Engl J Med. 2007 Nov 29; 357(22): 2277-84.
  5. Offre de soins de Santé- Carte sanitaire, situation de l’offre de soin, octobre 2019.available from : (Accessed February 10, 2021)
  6. Ige TA, Hasford F, Tabakov S, Trauernicht CJ, Rule A, Azangwe G, et al. MEDICAL PHYSICS DEVELOPMENT IN AFRICA–STATUS, EDUCATION, CHALLENGES, FUTURE. Med Phys Int, SI, History of Medical Physics. 2020;3.
  7. Saikouk H, Ou-Saada I, Bentayeb F, Boutayeb S, Eddaoui K. Medical physics status in Morocco: education, training and evolution. MEDICAL PHYSICS INTERNATIONAL. 2019;7(3):282.
  8. ICRP Publication 60, 1991. 1990 Recommendations of the International Commission on Radiological Protection. ICRP Publication 60. Ann. ICRP 21 (1-3).
  9. Vañó E, Miller DL, Martin CJ, Rehani MM, Kang K, Rosenstein M, et al. ICRP publication 135: diagnostic reference levels in medical imaging. Annals of the ICRP. 2017 Oct;46(1):1-44.
  10. Nenot JC, Brenot J, Laurier D, Rannou A, Thierry D. ICRP Publication 103. The 2007 Recommendations of the International Commission on Radiological Protection. 2007.
  11. Semghouli S, Amaoui B, Hakam OK, Choukri A. Radiation exposure during pelvimetry CT procedures in Ibn Sina Children's Hospital of Rabat. Radiation Physics and Chemistry. 2020 Oct 1;175:108087.
  12. Agence fédérale de Contrôle nucléaire - AFCN, SCANNERS CT, Available from : (accessed December 10, 2020)
  13. Dose Reduction in CT while Maintaining Diagnostic Confidence: A Feasibility/Demonstration Study. Radiation Safety and Monitoring Section. International Atomic Energy Agency, Vienna International Centre. PO Box 100, 1400 Vienna, Austria.
  14. European Commission. Diagnostic reference levels in thirty-six European countries. Radiation Protection No 180. 2014.
  15. ACR A. AAPM–SPR Practice Parameter for Diagnostic Reference Levels and Achievable Doses In medical X-Ray Imaging. ACR: Hong Kong, China. 2018.
  16. Stamm G, Nagel HD. CT-expo--a novel program for dose evaluation in CT. RoFo: Fortschritte auf dem Gebiete der Rontgenstrahlen und der Nuklearmedizin. 2002 Dec 1;174(12):1570-6.
  17. Gao Y, Quinn B, Mahmood U, Long D, Erdi Y, Germain JS, A comparison of pediatric and adult CT organ dose estimation methods. BMC Med. Imaging. 2017; 17(1): 1-17.
  18. Salama DH, Vassileva J, Mahdaly G, Shawki M, Salama A, Gilley D, Rehani MM. Establishing national diagnostic reference levels (DRLs) for computed tomography in Egypt. Physica medica. 2017 Jul 1;39:16-24.
  19. Nyathi M, Shivambu GI. Local diagnostic reference levels for common computed tomography procedures at a tertiary hospital in South Africa. Iranian Journal of Medical Physics. 2019;16(5):349-54.
  20. Kanal KM, Butler PF, Sengupta D, Bhargavan-Chatfield M, Coombs LP, Morin RL. US diagnostic reference levels and achievable doses for 10 adult CT examinations. Radiology. 2017 Jul;284(1):120-33.
  21. Ekpo EU, Adejoh T, Akwo JD, Emeka OC, Modu AA, Abba M, et al. Diagnostic reference levels for common computed tomography (CT) examinations: results from the first Nigerian nationwide dose survey. Journal of radiological protection. 2018 Mar 13;38(2):525.
  22. Sarma A, Heilbrun ME, Conner KE, Stevens SM, Woller SC, Elliott CG. Radiation and chest CT scan examinations: what do we know?. Chest. 2012 Sep 1;142(3):750-60.
  23. Benmessaoud M, Dadouch A, Talbi M, Tahiri M, El-Ouardi Y. Diagnostic reference levels for paediatric head computed tomography in Morocco: a nationwide survey. Radiation Protection Dosimetry. 2020 Oct;191(4):400-8.
  24. Wulandari PI, Talumantak KB, Iffah M, Ryangga D, Ariwidiastuti CI. Diagnostic reference levels: a review. J. Med. Sci. Clin. Res.. 2018;6:508-14.
  25. Ferderbar ML, Doyle TE, Samavi R, Koff D. An environmental scan of the national and provincial diagnostic reference levels in Canada for common adult computed tomography scans. Canadian Association of Radiologists' Journal. 2019 May;70(2):119-24.
  26. Narciso LD, Lima NW, Dartora CM, Marques da Silva AM. A contribution to the establishment of diagnostic reference levels in computed tomography in Brazil. InWorld Congress on Medical Physics and Biomedical Engineering. 2015; 737-40.
  27. GUIDANE NATIONAL DIAGNOSTIC REFERENCE LEVELS UK, FROM 19 AUGUST 2019. Available from: (accessed August, 2019).
  28. Bolowia N. Establishment of computed tomography diagnostic reference levels in Tobruk. J. Med. Diagn. Meth.. 2018;7.
  29. Foley SJ, McEntee MF, Rainford LA. Establishment of CT diagnostic reference levels in Ireland. The British journal of radiology. 2012 Oct;85(1018):1390-7.
  30. Fukushima Y, Tsushima Y, Takei H, Taketomi-Takahashi A, Otake H, Endo K. Diagnostic reference level of computed tomography (CT) in Japan. Radiation protection dosimetry. 2012 Aug 1;151(1):51-7.
  31. Etard C. Doses délivrées aux patients en scanographie et en radiologie conventionnelle. IRSN Rapport DRPH. 2010;12:2010.
  32. Korir GK, Wambani JS, Korir IK, Tries MA, Boen PK. National diagnostic reference level initiative for computed tomography examinations in Kenya. Radiat Prot Dosimetry. 2016; 168(2): 242-52.
  33. Santos J, Foley S, Paulo G, McEntee MF, Rainford L. The establishment of computed tomography diagnostic reference levels in Portugal. Radiation protection dosimetry. 2014 Feb 1;158(3):307-17.
  34. Treier R, Aroua A, Verdun FR, Samara E, Stuessi A, Trueb PR. Patient doses in CT examinations in Switzerland: implementation of national diagnostic reference levels. Radiation protection dosimetry. 2010 Dec 1;142(2-4): 244-54.
  35. Simantirakis G, Hourdakis CJ, Economides S, Kaisas I, Kalathaki M, Koukorava C, et al. Diagnostic reference levels and patient doses in computed tomography examinations in Greece. Radiation protection dosimetry. 2015 Feb 1;163(3):319-24.
  36. Sohrabi M, Parsi M, Sina S. A New Dual-purpose Quality Control Dosimetry Protocol for Diagnostic Reference-level Determination in Computed Tomography. Health Physics. 2018 Aug 1;115(2):252-8.
  37. Shrimpton PC, Hillier MC, Meeson S, Golding SJ. Doses from computed tomography (CT) examinations in the UK-2011 review. Public Health England Report PHE-CRCE-013. Chilton, UK: Public Health England; 2014.
  38. Lahham A, ALMasri H, Kameel S. Estimation of female radiation doses and breast cancer risk from chest CT examinations. Radiat Prot Dosimetry, 2018; 179(4): 303-9.
  39. Nishizawa K, Maruyama T, Takayama M, Okada M, Hachiya JI, Furuya Y. Determinations of organ doses and effective dose equivalents from computed tomographic examination. Br J Radiol, 1991;  64(757): 20-8.
  40. Origgi D, Vigorito S, Villa G, Bellomi M, Tosi G. Survey of computed tomography techniques and absorbed dose in Italian hospitals: a comparison between two methods to estimate the dose–length product and the effective dose and to verify fulfilment of the diagnostic reference levels. Eur. Radiol.. 2006; 16(1): 227-37.
  41. Aldrich JE, Bilawich AM, Mayo JR. Radiation doses to patients receiving computed tomography examinations in British Columbia. Can Assoc Radiol J, 2006; 57(2): 79.
  42. Tsai HY, Tung CJ, Yu CC, Tyan YS. Survey of computed tomography scanners in Taiwan: dose descriptors, dose guidance levels, and effective doses. Med. Phys. 2007; 34(4): 1234-43.
  43. Akpochafor MO, Omojola AD, Obed RI, Adeneye SO, Adewa OJ, Ekpo MAEl. In-house-developed phantoms for organ dose measurements using bovine tissues: A comparison study with CT-Expo simulation software. J Radiat Cancer Res. 2019; 10(2): 108.
  44. Franck C, Smeets P, Lapeire L, Achten E, Bacher K. Estimating the patient-specific dose to the thyroid and breasts and overall risk in chest CT when using organ-based tube current modulation. Radiology. 2018; 288(1): 164-9.
  45. Ngaile JE, Msaki PK. Estimation of patient organ doses from CT examinations in Tanzania. J. Appl. Clin. Med. Phys.. 2006; 7(3): 80-94.
  46. Akpochafor MO, Omojola AD, Habeebu MY, Ezike JC, Adeneye SO, Ekpo MA, et al. Computed tomography organ dose determination using ImPACT simulation software: Our findings in South-West Nigeria. Eurasian Journal of Medicine and Oncology. 2018;2(3):165-72.
  47. Sulemana H, Inkoom S, Sosu E, Schandorf C. Estimation of absorbed and effective doses in organs through computed tomography examinations using automatic exposure control and fixed tube current techniques: A phantom case study. Iranian Journal of Medical Physics. 2020;17(1):58-65.
  48. Oyedokun O, Arogunjo A, Fatukasi J, Egberongbe A. Diagnostic Reference Level of Computed Tomography Examinations and Need for Dose Optimization in Ondo State, Nigeria. Iranian Journal of Medical Physics. 2020;17(4):266-72.