Empirical Analysis of Radiation Dose Patterns and Optimisation Gaps in CT Chest Examinations Across South South Nigerian Teaching Hospitals

CT chest examinations deliver significant radiation doses and their dose patterns across Nigerian teaching hospitals have not been empirically analysed at a regional level despite rapid growth in CT utilisation across the South South zone. This study empirically analyses radiation dose patterns and identifies optimisation gaps in CT chest examinations at teaching hospitals in Rivers, Delta, Edo, Cross River, Bayelsa, and Akwa Ibom States. A prospective multi-centre dose audit recruits 300 consecutive adult CT chest examinations per included hospital, recording volume CT dose index, dose-length product, scan length, tube current modulation activation status, and reconstruction algorithm type. Mixed-effects regression modelling in R identifies patient-level, protocol-level, and site-level predictors of dose variation. Available CT chest dose literature from South South Nigeria identifies substantial inter-hospital dose variability, with DLP values ranging from 2.4 to 7.8 times national reference levels, primarily attributable to absent tube current modulation and fixed manual technique use. The European CT diagnostic reference levels and IAEA patient dosimetry guidance provide the analytical benchmarks. Findings are expected to quantify the contribution of protocol-level factors to observed dose variation, filling a gap in regional CT dose evidence. Recommendations address a South South Nigeria CT protocol harmonisation initiative, mandatory iterative reconstruction implementation, and CT clinical governance benchmarking across teaching hospitals. Keywords: CT chest, radiation dose, dose optimisation, South South Nigeria, multi-centre audit.