Objective To evaluate the radiation dose levels induced by secondary neutrons at different locations inside proton therapy treatment rooms, and analyze the distribution characteristics of neutron energy spectra by combining experimental measurements with simulations, and to provide a theoretical basis and technical support for radiation protection design and management in proton therapy. Methods Multiple representative measurement points were established in the treatment rooms of two hospital-based proton therapy centers. The DIAMON neutron spectrometer was employed to perform in-situ measurements of secondary neutron doses and energy spectra. Three-dimensional simulation models of treatment rooms were constructed using the FLUKA code to simulate the generation and transport of secondary neutrons. Results Measurements showed that the neutron dose was highest near the target region, reaching up to 4293.750 µSv/h. The doses at the maze entrance were the next highest, ranging from 422.091 to 489.268 µSv/h, while the doses in the middle section of the maze ranged from 2.860 to 6.727 µSv/h. The neutron energy spectra exhibited a triple-peak pattern. Conclusion Significant accumulation of secondary neutrons was observed near the target and in the maze regions during proton therapy, with intermediate-energy neutrons being the dominant dose contributor. The consistency between measurements and simulations validated the reliability of the model, which can provide a basis for optimizing treatment room shielding and controlling occupational exposure for staff.

Objective To investigate and analyze the occupational stress levels and influencing factors among radiation workers in China, and provide a reference for alleviating occupational stress and promoting mental health. Methods Using the general situation questionnaire, Effort-Reward Imbalance questionnaire, and radiation protection knowledge questionnaire, a convenience sampling method was adopted to investigate the occupational stress of 243 radiation workers in Liaoning, Fujian, Guangdong, and Xinjiang provinces. The independent samples t-test, one-way analysis of variance, chi-square test, and binary logistic regression were used to analyze the influencing factors. Results The average score of Effort-Reward Imbalance was 0.97 ± 0.22, and 100 (41.15%) radiation workers had occupational stress. There were significant differences in the detection rate of occupational stress among radiation workers of different ages, working years in radiation positions, monthly incomes, daily sleep durations, and daily working hours (P < 0.05). Logistic regression analysis identified daily working hours as a factor contributing to occupational stress. Conclusion The occupational stress among radiation workers in China is relatively severe. It is recommended to pay attention to the associated risks and implement targeted intervention measures to reduce the impact of occupational stress.

With the widespread application of proton therapy in tumor radiation treatment, the health effects of secondary neutron radiation on patients and medical personnel have become a key concern in radiation protection. Currently, there is no commonly accepted technical standard for neutron dose measurement in proton therapy, making it difficult to compare neutron doses across studies and hindering the standardized development of radiation protection strategies. This paper provides a systematic review of commonly used neutron dose measurement methods and Monte Carlo simulation approaches. This article also explores the key challenges and potential improvements in neutron dose measurement in proton therapy.

Objective To analyze the impact of different maze structures of medical electron linear accelerator on the radiation level at the entrance of the treatment room. Methods The Monte Carlo simulation method was used to compare the radiation field distribution in two accelerator rooms with different maze widths and to conduct a detailed analysis of the radiation levels. Results The radiation level at the entrance of the accelerator room with a wide maze was significantly higher than that at the entrance of a compact maze. The neutron radiation level at the entrance of the narrow maze model decreased by 38.6% compared to the wide maze model, and the level of X-ray radiation also showed a declining trend. Conclusion When designing medical electron linear accelerators, a compact maze structure should be adopted to reduce the setting of unnecessary space, thereby lowering the radiation level at the entrance of the treatment room and enhancing the effectiveness of radiation protection.

Objective To investigate the current situation of occupational stress among radiation workers in nuclear power plants in China, to explore the factors influencing occupational stress, and to provide a reference for improving occupational stress. Methods A convenient sampling method was adopted to investigate the occupational stress of 100 radiation workers in two nuclear power plants in Fujian and Liaoning, using the general situation questionnaire, effort-reward imbalance questionnaire, and the radiation protection knowledge questionnaire. Independent samples t-test, one-way analysis of variance, chi-square test, and binary logistic regression analysis were used to examine the current situation of occupational stress and the influencing factors. Results The average value of effort-reward imbalance was 0.99 ± 0.15 and 47 (47%) radiation workers had occupational stress. There were significant differences in the detection rate of occupational stress among radiation workers with different ages, years of radiation work, monthly incomes, sleep durations (day), and exercise habits (P < 0.05). Logistic regression analysis showed that monthly income, sleep duration (day), and exercise habits were the influencing factors for occupational stress. Conclusion The occupational stress of radiation workers in nuclear power plants is a serious issue influenced by many factors. Attention should be given to this issue, and targeted interventions should be implemented to improve the social and working environment of this occupational group and reduce the level of occupational stress.

Objective To compare the results of accumulation and continuation methods in indoor radon measurement. Methods The radon concentrations in 30 households in 7 provincial capital cities of China were simultaneously measured using both accumulation and continuation methods. Results The radon concentration measured by accumulation method in 30 households ranged from 21 to 323 Bq/m³, with a median M(P₂₅, P₇₅) of 70.5 (43.8, 111). The radon concentration measured by the continuation method ranged from 16.1 to 258 Bq/m³, with a median M(P₂₅, P₇₅) of 100 (51.3, 141). The average relative percent deviation between the two measurement methods was 41.8%. There were significant differences among the measurement results at 8, 16, and 24 h by the continuation method. Pairwise comparisons showed there were statistical diffferences between 8 h and 16 h, as well as between 8 h and 24h; however, no statistical significance was found (P < 0.05), between 16 h and 24 h. Conclusion The overall continuous measurement results of the 30 households were higher than those of cumulation method. The comparison between accumulation and continuation measurement results did not show a high level of correlation (r=0.49). The continuation method is significantly affected by environmental factors, and the length of the measurement period can affect the measurement results. The selection of indoor radon measurement methods should consider the purpose, sample size, and environmental conditions.

OBJECTIVE: We aimed to analyze the current indoor radon level and estimate the population risk of radon-induced lung cancer in urban areas of China. METHODS: Using the passive monitoring method, a new survey on indoor radon concentrations was conducted in 2,875 dwellings across 31 provincial capital cities in Chinese mainland from 2018 to 2023. The attributable risk of lung cancer induced by indoor radon exposure was estimated based on the risk assessment model. RESULTS: The arithmetic mean (AM) and geometric mean (GM) of indoor radon concentrations were 65 Bq/m³ and 55 Bq/m³, respectively, with 13.6% of measured dwellings exceeding 100 Bq/m³ and 0.6% exceeding 300 Bq/m³. The estimated number of lung cancer deaths induced by indoor radon exposure was 150,795, accounting for 20.30% (95% CI: 20.21%-20.49%) of the lung cancer death toll. CONCLUSION This study provided the most recent data on national indoor radon levels in urban areas and the attributable risk of lung cancer. These results served as an important foundation for further research on the disease burden of indoor radon exposure and radon mitigation efforts.
Radon/analysis* ; China/epidemiology* ; Air Pollution, Indoor/analysis* ; Lung Neoplasms/etiology* ; Humans ; Cities/epidemiology* ; Air Pollutants, Radioactive/adverse effects* ; Neoplasms, Radiation-Induced/etiology* ; Risk Assessment ; Radiation Monitoring

In recent years, occupational stress has become a focus of public attention in public health in China and abroad. Radiation workers are exposed to ionizing radiation in their daily work, which further exacerbates their levels of occupational stress. This not only affects their physical and mental health, but also increases the potential for radiation incidents or accidents. Based on the literature on occupational stress among radiation workers in China throughout the years, this article provides a summary, conclusion, and systematical analysis of the research status of occupational stress among radiation workers, with a detailed sorting of the data. It explores key research issues and directions and provides reference for future work.

Objective To investigate the indoor radon concentration and its changing trend in northeastern China. Methods We measured indoor radon levels cumulatively for over three months by solid state nuclear track detection in a total of 261 houses in multi-story or high-rise buildings in Shenyang, Changchun, Harbin, Heihe, and Yichun in northeastern China. The measurement lasted one year in Changchun for seasonal changes. Results The average indoor radon concentration in the five cities was 88 Bq/m³, ranging from 12 to 558 Bq/m³. The indoor radon concentrations were ≤ 100 Bq/m³ in 75.1% of the houses, and ≤ 300 Bq/m³ in 97.7% of the houses. The indoor radon concentration increased with the age of buildings. The indoor radon concentration was highest in winter, and it was higher in summer than in autumn and spring. Conclusion The indoor radon concentration in northeastern China increased compared with the data of 1980s and 1990s. It is highest in the winter heating season, and higher in summer than in spring and autumn. Indoor radon exposure deserves attention.

Since the implementation of the Measures for the Management of Radiation Workers’ Occupational Health in November 2007, it has played an extremely important role in protecting the occupational health of radiation workers. There are more than 700 000 radiation workers in about 100 000 workplaces with potential radiation exposure, as well as a large number of miners exposed to high levels of radon. As the radiation health monitoring project suggests, measures of occupational health management such as personal dose monitoring and occupational health examination of radiation workers have been widely implemented and achieved good results in the protection of radiation workers. However, the risks of chromosomal aberration and specific turbidity of the eye lens of radiation workers have increased in high-risk positions such as interventional radiology, nuclear medicine, and industrial flaw detection. The control of high radon exposure in miners needs to be strengthened. It is necessary to adapt to the new situation in view of new challenges and actively promote the revision of the Measures for the Management of Radiation Workers’ Occupational Health, so as to further improve the occupational health management of radiation workers in China.