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. Result 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. Conclusion 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).