Diagnostic reference levels for indication-based CT categories in pediatric CT: data from an international registry

Objectives: Computed tomography (CT) radiation doses vary depending on medical indications, protocols, and local practice. Our aim is to establish diagnostic reference levels (DRLs) for CT categories based on clinical indications in pediatric patients. Materials and methods: We analyzed CT data from an international dose registry retrospectively, including scans performed in children under 18 years at 143 facilities between January 2016 and January 2021. DRLs were calculated for volumetric CT dose index (CTDI _vol), dose-length product (DLP), and size-specific dose estimate (SSDE) across 14 CT categories, which reflect both the anatomic areas and radiation dose levels (low, routine, high dose) required by imaging indications within the anatomic areas. We compared the routine dose categories for head, chest, and abdomen/pelvis scans between facilities in the United States (U.S.) and Europe. Results: A total of 95,047 CT scans (mean age, 10.4 ± 5.6 years, 54% male), including 41 different indications, were included. DRLs increased with increasing age group (p < 0.05 for trend). For the head and the abdomen/pelvis body regions, there was greater variation between the CT categories than between the indications within the categories, suggesting these categories are valid. For example, in 10- to 15-year-old children, the DRLs for the DLP increased from 362 mGy·cm for head low dose to 2058 mGy·cm for head high dose. The U.S. DRLs were similar to the European for head categories, but were around twice as high for routine dose chest, and abdomen/pelvis. Conclusions: We have established DRLs for indication-based CT category age groups to help standardize practice. Key Points: Question CT categories are needed to reflect body regions and clinical indications with similar radiation dose requirements in pediatric patients. Findings Doses varied more between CT categories than within. DRLs for chest and abdomen/pelvis were about twice as high in the U.S. as in Europe. Clinical relevance DRLs as a function of patient age were developed for 14 broad anatomy- and indication-based CT categories in children using registry data.