Assessment of Radiation Shielding Integrity and Structural Compliance in Computed Tomography Facilities in Delta State, Nigeria.

Computed tomography (CT) facilities are major contributors to medical radiation exposure, raising safety concerns for patients, staff, and the general public. Shielding design is critical, yet often applied uniformly without accounting for local workload or geometry. This study evaluated shielding efficiency in CT facilities across Delta State, Nigeria. A cross-sectional survey was conducted in six CT centers (two government, four private). Facility specifications, room dimensions, and workload data were recorded. Radiation exposure was measured at primary and secondary barriers using calibrated survey meters. Required shielding thickness was calculated using NCRP 49 methodology. Statistical analyses included descriptive statistics, ANOVA, Kruskal-wallis tests, and correlation matrices. Installed shielding (mean 2.738 mmPb) exceeded calculated requirements (mean 0.444 mmPb) by ~6.7 times, with average excess shielding of 2.294 mmPb. Shielding efficiency averaged 83.8% (range 62-95%) and positive skewness (3.113), indicating outlier exceedances. Material equivalence analysis revealed that 115.8 mm steel, or 127.9 mm glass equaled 1 mm lead. Strong correlations (r > 0.97) confirmed consistency across material equivalents, while higher design shielding strongly predicted overshielding (r ꞊ 980). Inter-facility comparisons showed significant differences in shielding efficiency and excess shielding (p ˂ 0.001). CT facilities in Delta State demonstrate conservative overshielding, ensuring safety but reflecting inefficiencies in material use. Despite adequate protection, extreme dose outliers highlight the need for site-specific shielding assessments, continuous monitoring, and optimization in line with as low as reasonably achievable (ALARA) principles.

Radiation shielding, dose optimization, computed tomography, patient safety, occupational exposure.

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