Purpose: To analyze radiation dose data collected from CT exams performed at Southern California Kaiser facilities for the creation and maintenance of up-to-date reference levels and dose index ranges. These ranges are used to identify and alert dose outliers for further investigation as well as compare consistency and changes before and throughout COVID-19.
Methods: Diagnostic reference levels (DRL’s) provide a means for practices to compare radiation dose data to benchmarks derived from aggregated dose data collected on a local, regional, or national level. Dose index ranges are established to provide guidance correlated to patient dose‐related issues and other regulatory‐ or accreditation‐related requirements pertaining to the performance of diagnostic CT procedures. Data was collected from 15 facilities using 58 scanners for a total of 1,316,850 scans between January 2019 and June 2021. The mean CTDIvol, dose-length product, 75th, 95th, and 99th percentiles were calculated separately for adult and pediatric patients. Dose index ranges were created for 6 categories (head, neck, abdomen, chest, pediatric head, and pediatric abdomen) based on anatomical region and procedure, defined at each percentile range.
Results: Preliminary analysis shows dose index ranges remained consistent before and throughout COVID-19. The mean CTDIvol and standard deviation year-to-year for exams of the 6 anatomical regions over the 2.5 years were as follows: head, 57 mGy (dev. 0.17%); neck, 18 mGy (dev. 0.41%); abdomen, 17 mGy (dev. 0.15%); 14 mGy (dev. 0.25%); pediatric head 41 mGy (dev. 1.75%); and pediatric abdomen 7 mGy (dev. 0.22%). The 75th percentiles calculated were in agreement with national and state published DRL’s for California for similarly grouped anatomical regions.
Conclusion: This summarized radiation dose data is key in establishing and maintaining current dose benchmarks for institutional evaluation. Well-defined reference levels and index ranges play a significant role in optimizing local practices.