Current Trends in Computed Tomography Practices in Japan and the Role of Referring Physicians in Radiation Exposure Management.

Objective In 2020, Japan recorded the highest number of computed tomography (CT) units per million population among Organization for Economic Co-operation and Development (OECD) countries. This surplus may lead to unnecessary procedures, increased costs, and increased radiation exposure. This study estimated CT procedures per 1,000 population and analyzed their usage by sex and age using governmental surveys and health insurance claim data. Methods Data from 2008 to 2020 were obtained from the Ministry of Health, Labour and Welfare medical institution surveys. Age- and sex-specific data (2014-2022) were extracted from the Japanese National Database of Health Insurance Claims and Specific Health Checkups (NDB Open Data, Japan). The population data were sourced from the Ministry of Internal Affairs and Communications. Results The number of CT procedures performed per 1,000 population increased from 210 in 2008 to 283 in 2020. The number of CT procedures performed per unit increased from 2,170 in 2008 to 2,445 in 2020. NDB Open Data revealed an annual increase in CT procedures per 1,000 population, from 221 in 2014 to 255 in 2022. Men underwent more CT scans than women across all age groups, with CT procedures per 1,000 population increasing with age (e.g. in 2022, 27 in men 0-9 years old to 1,182 in men ≥90 years old and 18 in women 0-9 years old to 835 in women ≥90 years old). Conclusion The number of CT procedures performed per 1,000 population in Japan has steadily increased. With the highest OECD rates in 2017 and 2020, mitigating overuse requires a dose management system, referral guidelines, and education regarding radiation risks for referring physicians.