Justification and optimisation of paediatric CT in prefectures around Tokyo.

[Background] Although 'justification' and 'optimisation' are recommended as principles for reducing paediatric medical exposure, it is unclear whether these are actually implemented in general hospitals. [Method] Targeting emergency hospitals in the Tokyo area, we conducted a survey on the current status of paediatric acute abdomen, including diagnostic imaging methods used by physicians (n = 169) and exposure doses from CT scans employed by radiology technologists (n = 172). [Results] Fewer than half of physicians were aware of the guidelines for acute appendicitis, and utilisation was very low at 17%. However, ultrasound was the most commonly performed first imaging test at 77%. On the other hand, among technologists, 93% were aware of Japan's diagnostic reference level (DRL), and optimisation was applied at 83% of facilities. Otherwise, there were some facilities that used high-dose settings that exceeded the DRL, indicative of a trend towards a long-tailed distribution. [Discussion] Although awareness of the diagnostic guidelines was low, they were already being justified in general hospitals. As the guidelines become more widely known, the number of CT imaging phases may be further reduced. DRL was widely used and optimised. However, some facilities used high radiation settings, and these cannot be ignored.