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Diagnostic reference levels (DRLs) for chest radiography, non-contrast head computed tomography and mammography examinations in Nigeria: review of national data


Aims and objectives

To establish the national diagnostic reference levels (DRLs) for chest radiography, non-contrast head computed tomography (CT) and mammography examinations of adults in Nigeria.

Materials and methods

The study consisted of review of published studies on DRLs in Nigeria found in the internet using Google search engine from 2005 to 2019. Only publications containing substantial parts of the exposure parameters were used for the studies.


For chest radiography, the mean parameters for posterior–anterior (PA) view were, tube voltage 80 (33–100) kV, tube current 30.8 (0.05–100) mAs, film–focus distance (FFD) 140 (62–178) cm, mean entrance dose 2.6 (0.12–7.7) mGy and mean effective dose (MED) 0.05 (0.018–0.16) mSv. For head CT, tube voltage 120 (100–140) kV, tube current 390 (215–550) mA, CT dose index (CTDI vol) 67 (25–88) mGy, dose length product (DLP) 1410 (320–1903) mGy cm and MED 2.8 (1.8–3.99) mSv. For breast mammography, tube voltage 23.90 (20.5–31) kV and 23.80 (20.03–31) kV, tube current 110.54 (60–417) mA and 110.46 (35–417) mA, entrance skin dose 0.83 (0.08–5.36) mSv and 3.12 (0.26–21.26) mSv, and mean glandular dose (MGD) 1.32 (0.02–6.41) mGy and 2.03 (0.07–8.59) mGy for craniocaudal and mediolateral views, respectively. For both breasts combined, the mean entrance skin dose is 2.5 (0.30–5.1) mSv while the MGD is 1.66 (0.31–2.5) mGy.


Patients in Nigeria receive comparative higher radiation doses for chest radiography and head CT but are exposed to lower radiation doses for breast mammography than obtained in the European Union (EU).

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The authors are grateful to the following persons, Mr. Patrick Madubuko of Department of Haematology Nnamdi Azikiwe University, Nnewi Campus and Dr. Okechukwu Oguzie of Military Hospital Lagos who greatly assisted in this study. Mr. A.O. Eze who ensured that this study was concluded. The authors are also grateful to Chief Isaac Asomgba, Mrs Esther Asomgba, Mrs Medline Nwabueze and Mrs Jane Nkechinyere Eze for their numerous assistance that made the completion of this study possible. The assistance of the secretarial staff of Mr AC Daniel and company at Nnewi, Anambra State is also highly appreciated. The authors are also grateful to Mr Ozoemenam Ugochukwu of Department of History and International studies, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria, for his logistic assistance throughout this study.

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Correspondence to Kenneth Chukwudi Eze.

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The authors did not receive support from any organization for this work. The authors have no relevant financial or non-financial interests to disclose.

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This is an observational study consisting of a review of already published studies. The Nnamdi Azikiwe University, Awka, Research Ethics Committee confirmed that no ethical approval was required.

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Informed consent was waived or not required. This study consisted of secondary analysis of already existing data.

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Eze, K.C., Uduma, F., Omidiji, O.A. et al. Diagnostic reference levels (DRLs) for chest radiography, non-contrast head computed tomography and mammography examinations in Nigeria: review of national data. Chin J Acad Radiol 5, 99–106 (2022).

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  • Diagnostic
  • Reference Level
  • Radiography
  • Mammography
  • Computed Tomography