Age and size dependent diagnostic reference levels and achievable doses for 48 types of CT examinations: a multicenter cross-sectional study of one million CT examinations in China

To establish diagnostic reference levels (DRLs) and achievable doses (ADs) of 48 commonly used CT examinations including advanced CT techniques such as dual energy CT (DECT) based on patient age and size in Chinese multicenter cohort with one million CT examinations.

Radiation dose data on 48 commonly used CT examinations including conventional CT examinations, CT angiography (CTA), and DECT examinations at four Chinese university hospitals between January 2016 and December 2018 were retrospectively collected. For all CT examinations, dose indexes were analyzed based on patient age and size. ADs and DRLs for volume CT dose index (CTDI_vol), dose-length product (DLP), size-specific dose estimate (SSDE) and effective dose (ED) were analyzed.

1,001,190 CT examinations were available for dose analysis. The most common examination was non-enhanced chest CT (26.25%) with the age-based CTDI_vol AD ranging from 2.50 to 7.66 mGy and DRL from 3.67 to 10.29 mGy. Coronary CTA was the most used CTA (42.19%), with CTDI_vol AD ranging from 8.08 to 13.65 mGy and DRL from 11.73 to 22.21 mGy. DECT of extremity was the most used DECT examination (48.24%), with CTDI_vol AD ranging from 2.23 to 2.55 mGy and DRL ranged from 2.66 to 4.61 mGy. DRLs and ADs for size-based CTDI_vol, DLP, SSDE and ED increased consistently with patient size.

This multicenter study provided DRLs of 48 commonly used CT examinations including conventional CT examinations, CTA, and DECT examinations based on patient age and size. Further research is required to develop national DRLs to guide CT radiation optimization.