ESTABLISHMENT OF LOCAL DIAGNOSTIC REFERENCE LEVELS FOR CONVENTIONAL RADIOGRAPHY IN DELTA STATE, NIGERIA: A MULTI-CENTRE DOSE ASSESSMENT STUDY

Abstract

Diagnostic Reference Levels (DRLs) are for optimizing radiation protection. However, data from low- and middle-income countries are under-represented with no current DRLs for conventional radiography in Nigeria, to establish local multi-centre DRLs for common radiographic examinations in Delta State, Nigeria, a study in three government hospitals (761 adults, mean age 45.4±18.0 years) measured Entrance skin dose (ESD), Kerma-area product (KAP), and absorbed dose to the abdomen, chest, lumbosacral spine, pelvis and skull using a calibrated Unfor Multi-O-Meter 710L. Quality control (QC) tests were done following the IAEA protocols. The DRLs were set at the 75th percentile of the ESD distributions. All QC parameters were within the international limits. The mean ESD was significantly different between facilities (1.49–2.65 mGy). Proposed DRLs (75th percentile) are: abdomen 3.08 mGy, chest PA 0.53 mGy, lumbosacral spine 4.09 mGy, pelvis 3.99 mGy and skull 2.06 mGy which is much lower than the IAEA guidance levels (e.g., 10.0 mGy for the abdomen/pelvis). ESD correlated highly with mAs (r=0.878).These preliminary DRLs for Delta State represent evidence-based benchmarks below international levels. Even though QC was acceptable, the large inter-facility dose variation underscores the urgent need for protocol standardization and ongoing staff training in dose optimization, not just equipment compliance.