Diagnostic reference levels for specific clinical indications of computed tomography scans

Diagnostic reference levels (DRLs) are relevant tools for radiation dose optimization. This study performed a regional survey to evaluate dose values based on specific clinical indications (CIs) for adult Computed Tomography (CT) examinations in Northwestern Nigeria. Ten groups of CIs for diagnostic CT in adult patients were considered based on frequency. Data was collected for CT examinations covering the head, chest, and abdomenopelvic regions performed between 2019 and 2020, per center and CIs. Distributions of Volume CT Dose Index (CTDIvol) and examination Dose-Length Product (DLP) were assessed for each CI and gender. 993 single acquisition examinations were analyzed. Median CTDIvol values were closely gabbed in both genders for all examinations whereas median DLP values were higher for male compared to female patients for head and chest examinations, however, higher in female for abdominopelvic examinations. Median DLP difference in head CIs range from 0.7% in head trauma (1277 vs 1267 mG.cm) to 14% in dementia (1188 vs 1022 mG.cm), 17% in lung tumor (352 vs 292 mG.cm) to 20% in chest lesion with CKD (314 vs 251 mG.cm), and 8.4% in kidney stone (424 vs 463 mG.cm) to 18% in urothelial malignancy (423 vs 517 mG.cm) in abdominopelvic examinations. Analysis revealed no significant difference in median dose values among both genders, male and female for all CIs, F(2, 27) = 3.354, p =.997 for CTDIvol and F(2, 27) = 3.354, p =.998 for DLP. This study provides clinical indication-based dose reference values useful for optimizing clinical CT examinations.