Development of diagnostic reference levels and acceptable quality dose for computed tomography in an Indian tertiary care center

Background Computed tomography (CT) contributes substantially to medical radiation exposure, making diagnostic reference levels (DRLs) important for dose optimization. This study aimed to establish preliminary institutional DRLs and evaluate acceptable quality dose (AQD) at an Indian tertiary care center. Methods A cross-sectional observational pilot study included 58 CT examinations performed on a Siemens SOMATOM Definition Flash 128-slice scanner. Computed tomography dose index-volume (CTDIvol) and dose-length product (DLP) were analyzed for topogram and tomogram phases across the abdomen, cardiac, head, shoulder, spine, and thorax regions. The 75th percentile was used to propose institutional DRLs. Image quality was independently assessed by a radiologist using a five-point scale. Results Tomogram dose metrics varied substantially by anatomical region. The proposed CTDIvol DRLs ranged from 1.90 mGy for the shoulder to 74.06 mGy for the spine, with corresponding DLP DRLs ranging from 52.73 to 2461.19 mGy·cm. Adults had significantly higher tomogram doses than pediatric patients, whereas sex-based differences were not statistically significant. All scans received an image-quality score of 3, indicating diagnostically acceptable quality. Conclusions These findings provide preliminary institutional benchmarks for CT dose optimization and identify high-dose regions requiring protocol review. Larger, multi-center datasets are needed to validate the proposed DRLs and strengthen application of the ALARA principle.