Radioprotection 2026, 61( 2), 105 – 112 © J. Bazoma et al., Published by EDP Sciences, 2026 https:// doi. org / 10.1051 / radiopro / 2025026
Available online at: www. radioprotection. org
ARTICLE
Assessment of typical( DRL) values, size-specific dose estimates, organ doses and effective doses of adult patients undergoing computed tomography examinations in a university hospital in Brazzaville, Congo Republic
J. Bazoma 1, 2, 3, G. B. Dallou 1, 2,*, P. Ondo Meye 4, 5, R. N. Nzambi Mfoutou 1, R. R. C. Moubakou Diahou 1, 2, F. R. Moyikoua 1, 3 and C. Bouka Biona 1
1 Université Marien Ngouabi, Faculté des Sciences et Techniques, BP 69 Brazzaville, Congo. 2 Institut National de Recherche en Sciences Exactes et Naturelles, PB 2400 Brazzaville, Congo. 3 Centre Hospitalier Universitaire de Brazzaville, B. P 32 Brazzaville, Congo. 4 Direction Générale de la Radioprotection et de la Sûreté Nucléaire, Ministère de l ' Energie et des Ressources Hydrauliques, BP 1172
Libreville, Gabon. 5 Laboratory of atomic, molecular and Nuclear Physics, Department of Physics, Faculty of Science, University of Yaounde I, P. O. Box
812 Yaounde, Cameroon. Received: 23 December 2024 / Accepted: 7 August 2025
Abstract – This study aimed to assess typical values, size specific dose estimates, organ doses and effective doses of adult patients undergoing computed tomography( CT) examinations in a university hospital in Brazzaville, Congo Republic. The study involved 308 adult patients of which 51 % were female patients and 49 % were male patients. Median values of the distribution of dose-length product and volume CT dose index for each CT examination type were defined as typical values in agreement with the ICRP publication 135. Size-Specific Dose Estimates were calculated using the American Association of Physicists in Medicine methodology. Organ doses were computed following a methodology that uses dose coefficients and volume CT dose index. Effective doses were derived using the calculated organ dose values and tissue weighting factors given in ICRP publication 103. Typical values, size-specific dose estimates, organ doses and effective doses determined for female patients were greater than those determined for male patients. The study also showed that chest-abdomen-pelvis and abdomen-pelvis scans were associated with the highest effective dose while the head scan was associated with the lowest effective dose. The overall dose values determined in this study were significantly lower than those reported in selected studies reported in the literature.
Keywords: Typical values / size-specific dose estimates / organ dose / effective dose / Congo Republic
1 Introduction
Medical imaging, including computed tomography( CT), has made it possible to explore the interior of the body without opening it. CT has several advantages such as patient management in radiotherapy, and visualization of soft tissues and bony structures( Hussain, 2022). However, this device used for diagnostic purposes emits ionizing radiation( X-rays) which may be hazardous for humans( IAEA, 2018). The popularity of radiological examinations implies an increase in the collective dose of X-rays received by the patients( Gillet, 2018). It is therefore important to regularly measure
* Corresponding author: dg _ blanc @ yahoo. fr or estimate patient exposure and to analyze its evolution over time. This is mainly because the probability of radiation induced cancer increases with increasing radiation dose. Measuring or estimating patient dose is particularly necessary to ensure that medical facilities comply with regulations and use safe practices. Furthermore, studies on patient radiation dose provide valuable data for research and development of new medical imaging techniques. They help to evaluate the effectiveness of new technologies and new equipment in order to reduce patient dose while maintaining adequate image quality.
Patient dosimetry is the methodology used to measure or estimate the radiation dose received by patients during radiological procedures. Several radiation dose quantities may be used for this purpose. In CT, the main radiation quantities used are the volume CT Dose Index( CTDI vol, in
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