Background The monitoring of external radiation individual doses for radiation workers is a statutory task and serves as an important basis for the diagnosis of occupational diseases in this occupational group. Ensuring the accuracy and reliability of monitoring data is crucial for safeguarding the health of radiation workers.

Objective To evaluate and compare the capabilities and levels of external radiation individual dose monitoring conducted by radiation hygiene service institutions in Shanghai, to standardize relevant workflows, and to improve the accuracy and reliability of the monitoring service.

Methods From 2021 to 2023, annual intercomparisons of external radiation individual dose monitoring capabilities were organized for radiation hygiene service institutions in Shanghai. The study subjects were 19 to 21 radiation hygiene service institutions registered in Shanghai for each year and they all participated in the intercomparisons. The monitoring subjects included 16 district-level centers for disease control and prevention (CDCs) and 13 third-party testing agencies. Monitoring capabilities were analyzed based on single-group performance, comprehensive performance, and Q-value. In the intercomparison, a thermoluminescent dosimetry system was used to perform irradiation tests on thermoluminescence dosimeter made of lithium fluoride (magnesium, copper, phosphorus), LiF (Mg, Cu, P), and monitoring data for X-rays and γ-rays at different doses and radiation conditions were analyzed following a standard procedure specified by GBZ 207−2016. Statistical methods included t-test and Kolmogorov-Smirnov test, with statistical significance set at P<0.05.

Results From 2021 to 2023, the number of participating institutions was 19, 21, and 19, respectively, with an overall pass rate of 94.9% (56/59). Two institutions failed in 2022 and one in 2023. The number of institutions meeting the excellent standard in single-group and comprehensive performance was 9, 12, and 13, respectively, and the number of institutions ultimately rated as excellent was 3, 7, and 8,respectively, with an overall excellence rate of 30.5% (18/59) and an excellence conversion rate of 52.9%. The pass rates for single-group and comprehensive performance were both 98.3%. The number of groups with negative deviation was 1.86 times that of groups with positive deviation for X-rays, and 1.10 times for γ-rays. For X-rays, there was a statistically significant deviation between doses of less than 1.0 mSv and more than 1.0 mSv (P=0.01), while there was no significant difference in the single-group performance deviation between X-rays and γ-rays at the same dose. There was a statistically significant difference between the reported and reference values for X-rays in 2021 and 2022 (P<0.05), but no significant difference in 2023 (P>0.05); there was no significant difference between the reported and reference values for γ-rays over the three years (P>0.05).

Conclusion Over the past three years, the external radiation individual dose monitoring capability intercomparison results of radiation hygiene service institutions in Shanghai have shown that the pass rate remains at a high level, with the excellence rate increasing year by year. However, some institutions still need to improve their monitoring capabilities, and further cooperation among institutions and training for technical staff are needed to enhance the capabilities and standardization of external radiation individual dose monitoring in Shanghai.