Effect of a law amendment on dosimeter wearing in medical radiation workers: observational study.

OBJECTIVES: To evaluate the impact of a law amendment that reduced the eye lens dose limit on the use of personal dosimeters among radiation workers in medical settings. MATERIALS AND METHODS: A repeated cross-sectional survey was conducted at medical institutions across three periods: before the law amendment (control) and during the promulgation and implementation periods. Surveyors (radiological technologists) at each participating medical institution recorded dosimeter-wearing status among radiation workers. Data were collected via mail or email and analysed. The observed workers included physicians, nurses, and radiological technologists. RESULTS: The surveys were collected from 1194 workers in the control period, 1374 in the promulgation period, and 1194 in the implementation period, totalling 3762 workers. Post-law amendment, the overall wearing rate of primary personal dosimeters significantly increased from 64.6% to 77.9% (p < 0.001). Significant increases in wearing rates were observed among physicians and radiological technologists (p < 0.001). Among occupations, physicians showed the lowest wearing rates across all periods (control: 35.8%, promulgation: 56.7%, implementation: 62.6%), whereas radiological technologists showed the highest (control: 92.7%, promulgation: 98.5%, implementation: 99.5%). Regarding physician specialities, orthopaedic surgery exhibited the lowest compliance (control: 11.3%, promulgation: 35.4%, implementation: 24.7%). The proportion of workers without provision of a personal dosimeter declined from 5.9% to 1.9% (p < 0.001). CONCLUSIONS: Despite overall improvement following the law amendment, low compliance among physicians, particularly in orthopaedics, indicates the need for targeted interventions. CRITICAL RELEVANCE STATEMENT: Although dosimeter-wearing rates improved after Japan's eye dose limit revision, persistent low physician compliance-especially in orthopaedics-highlights the need for targeted strategies to strengthen radiation protection in clinical practice. KEY POINTS: The effect of reduced eye dose limits on dosimeter use remains unclear. Personal dosimeter usage increased significantly after the law amendment. Compliance remained low among orthopaedic physicians despite regulatory tightening. Targeted interventions are needed for low-compliance groups to ensure radiation protection.