ESTIMATION OF EFFECTIVE DOSE FOR PATIENTS UNDERGOING COMPUTED TOMOGRAPHY SCANS FROM SELECTED DIAGNOSTIC CENTERS IN SOUTHWESTERN NIGERIA

Computed Tomography (CT) is a major contributor to medical radiation exposure worldwide. In Nigeria, the absence of national Diagnostic Reference Levels (DRLs) poses challenges for patient dose optimization and radiation protection. This study estimated effective doses (EDs) from common CT examinations in selected diagnostic centers/hospitals in Southwestern Nigeria and compared the results with International Standards. A retrospective cross-sectional study was conducted using convenience samples of 348 CT examinations, comprising head (n = 212), chest (n = 56), and abdomen-pelvis (n = 80) scans, obtained from one government-owned and one private hospitals. Patient dose parameters, including Dose Length Product (DLP), were extracted, and effective dose (ED) was calculated using International Commission on Radiological Protection (ICRP) region-specific conversion recommended factors. Mean EDs for head CT were 2.5±1.0 and 1.9±0.7 mSv in the government and private hospitals, respectively. Chest CT yielded mean EDs of 11.1±8.1 and 15.4±4.9 mSv, while abdomen-pelvis CT recorded the highest value of 19.3±9.8 and 48.4±17.9 mSv, respectively. The student’s t-test showed significant differences (p < 0.05) in chest and abdomen-pelvis EDs between the hospitals. The results of EDs for head CT were lower than the established values from British Columbia and Canada, whereas the chest and abdomen-pelvis doses exceeded standard values by 23-193 %. These findings demonstrate considerable inter-hospital variation and elevated radiation doses for thoracic and abdominopelvic CT examinations. Therefore, there is urgent need for the CT dose optimization and the establishment of national DRLs in Southwestern Nigeria to strengthen radiation protection and improve patient safety.