Objective To analyze the layout and shielding effectiveness of medical accelerator vaults, and to provide a reference for the layout, shielding design, and optimization of protection of medical accelerator vaults. Methods Four medical accelerator radiotherapy vaults were selected. The layouts of these vaults were compared with the layout requirements in the radiation therapy protection standards. For each vault, the dose rates at four points of interest outside the shielding were calculated, including the primary shielding area, secondary shielding area, maze outer wall, and lateral shielding area. These values were then compared with the actual measurements obtained using a dose rate meter. Results All four vaults were located on the ground floor of the building and included a maze, with the auxiliary rooms all placed outside the treatment rooms. However, one vault was not located at one end of the building, and in another vault, the control room was exposed to direct irradiation of the useful beam. The calculated dose rates outside the primary shielding area ranged from 0.04 μSv/h to 0.62 μSv/h, while the measured values ranged from 0.10 μSv/h to 0.66 μSv/h, with the measured values being higher than the calculated ones. The calculated dose rates outside the secondary shielding area ranged from 0.0005 μSv/h to 0.12 μSv/h, those outside the maze outer wall ranged from 0.06 μSv/h to 0.18 μSv/h, and those outside the lateral shielding area ranged from 0.009 μSv/h to 0.15 μSv/h; the measured values were all below the detection limit. Conclusion Inadequate layouts were observed in some of the accelerator vaults. The calculated and measured dose rates at points of interest outside the vaults were both significantly lower than the shielding protection requirements in standards, indicating that the shielding designs were overly conservative. Construction units should follow the principle of optimization of radiation protection to design the layout and shielding reasonably and pay attention to the underestimation of dose rates outside the primary shielding caused by the tenth value layer.

Objective To investigate the annual effective doses to radiation workers caused by radon concentrations in the underground workplaces of medical institutions, and to provide a scientific basis for the prevention and control of indoor radon in underground places. Methods A typical sampling method was used to select 5-30 medical institutions in each of Hunan, Jiangxi, Guizhou, Hubei, and Sichuan provinces. A total of 66 monitoring points in 66 medical institutions were selected. The indoor radon concentrations in underground workplaces were measured cumulatively using CR-39 solid nuclear track detectors. The radiation dose to radiation workers was estimated according to the method outlined in the Requirements for control of indoor radon and its progeny (GB/T 16146—2015). The Kruskal-Wallis H test was used to compare the differences in indoor radon concentrations between different provinces. Results The average indoor radon concentration in the underground workplaces of 66 medical institutions was 69.8 Bq/m³, with the highest being 147.6 Bq/m³. The average indoor radon concentrations in the underground workplaces of medical institutions in Sichuan, Guizhou, Hubei, Jiangxi, and Hunan were 72.1, 83.2, 66.6, 88.4, and 61.5 Bq/m³, respectively. The annual effective doses to radiation workers caused by radon concentrations in underground workplaces were 0.57-0.83 mSv, with an average of 0.69 mSv. There was a significant difference in radon concentrations among provinces (P < 0.05). Conclusion The indoor radon concentrations and personnel exposure doses in the underground workplaces of monitored medical institutions comply with national control standards. However, continuous monitoring and necessary indoor radon prevention and control measures are still needed.

Objective To establish typical values for interventional diagnosis and treatment at our institution, use these values as a tool to evaluate patient medical exposure doses, and optimize radiation protection measures. Methods From June to December 2023, we collected information on 593 adult cardiovascular interventional diagnosis and treatment surgeries, including surgery type, equipment model, air kerma-area product (KAP), incident reference point air kerma (K_a,r), perspective time (FT), and exposure mode. Results The typical value of cardiovascular interventional diagnosis at our institution in 2023 was 27.5 Gy·cm². The typical value of cardiovascular interventional treatment was 70.0 Gy·cm². The FT, KAP, and K_a,r of interventional surgeries were significantly higher than those of interventional diagnosis (P < 0.01). There were significant correlations between FT, KAP, and K_a,r (P < 0.01). Conclusion The results of this study were slightly different from those of other studies. They provide typical data and reference values for cardiovascular interventional diagnosis and treatment dose levels in Beijing and are helpful for dose optimization between different medical institutions.

Objective To evaluate the current status in the implementation of GBZ/T 201.5-2015 Radiation shielding requirements for radiotherapy rooms-Part 5: Radiotherapy room of proton accelerators, identify issues in the application of its technical indicators, and provide a basis for the in-depth implementation and further revision of the standard. Methods In accordance with the Standardization Law of the People’s Republic of China and the Guidelines for Health Standards Tracking Evaluation (WS/T 536-2017), a combination of cluster sampling and stratified sampling methods was employed to select professionals involved in proton accelerator radiotherapy devices and facilities in three provinces (or municipalities directly under the central government) as the subjects of the survey. A questionnaire was developed to collect basic information about the subjects and their understanding and application of the technical indicators in the standard. A standard evaluation indicator system with a total score of 100 points was established to score the implementation of the standard (40 points), the technical content (30 points), and the effectiveness of the implementation (30 points). Results A total of 169 professionals from 107 institutions participated in the survey, with 79.88% of the respondents having at least 5 years of experience in radiation therapy and 74.56% holding intermediate or higher professional titles. The score of standard implementation was 18.3 points. The awareness rate exceeded 80%, indicating a high level of awareness about the standard. However, the scores for the dissemination and application of the standard were relatively low, accounting for 28% and 32% of their respective full marks. The technical content of the standard and the effectiveness of its implementation scored 27.0 and 26.6 points, respectively. The overall score in the evaluation of standard implementation was 72 points, with scores of 68.6, 72.3, and 75.0 for Beijing City, Shanghai City, and Jiangsu Province, respectively. Conclusion GBZ/T 201.5-2015 Radiation shielding requirements for radiotherapy rooms-Part 5: Radiotherapy room of proton accelerators is scientific and operable, and it is well-coordinated with relevant laws and standards. However, considering the development in FLASH technology and multi-chamber radiotherapy room, it is necessary to revise and improve the standard.

Objective To track and evaluate the implementation and application of the occupational health standard Radiation shielding requirements for radiotherapy room—Part 4: Radiotherapy room of ²⁵²Cf neutron afterloading (GBZ/T 201.4-2015) by radiation health technical service agencies, medical institutions, health supervision agencies, and radiotherapy facility design units, and to provide a scientific basis for the further revision and implementation of this standard. Methods Following the Guideline for health standards tracking evaluation (WS/T 536-2017) and the project implementation plan, relevant practitioners were randomly selected for a questionnaire survey. The survey primarily focused on their awareness, standard training, application, and revision suggestions of GBZ/T 201.4-2015. The results were summarized and analyzed. Results A total of 168 evaluation questionnaires were collected from relevant practitioners in 28 provinces. Only 31.6% of the respondents reported being “well familiar” or “ familiar” with the standard, 27.4% of the respondents believed that the standard was widely used, and 45.2% of the respondents believed that the standard could meet the needs of their work. Only 14.9% of the respondents had received relevant training on the standard, more than half of the respondents had not applied the standard within the past 10 years, and 45.2% of the respondents believed that the standard "needs to be revised". Conclusion Due to the small number of californium-252 neutron afterloading radiotherapy devices in operation on the market, the overall awareness of the standard is low, suggesting that relevant authorities need to strengthen training and publicity of the standard, and that certain sections of the standard need to be revised or merged.

Objective To investigate the levels of radionuclides in food in Beijing, China, and assess the committed effective dose to local residents from food intake. Methods From 2021 to 2022, a total of 65 food samples across 7 categories were collected in Beijing. The activity concentrations of radionuclides, including ¹³⁷Cs, ²¹⁰Pb, ²³⁸U, ²²⁸Ra, ²²⁶Ra, ⁴⁰K, ⁹⁰Sr, ²¹⁰Po, ³H and ¹⁴C, were measured using gamma spectrometry and radiochemical methods. By combining the monitoring results with dietary consumption data of Beijing residents and the internal dose coefficients for Chinese reference adult phantom, the committed effective dose was estimated. Results The levels of radionuclides in food in Beijing were within the normal background range, consistent with related surveys in China and abroad, with activity concentrations below national standard limits. No significant differences were found in the activity concentrations of ¹³⁷Cs, ²³⁸U, ²²⁸Ra, ²²⁶Ra and ⁴⁰K between food samples collected from key areas and those from control areas (P > 0.05). The committed effective doses calculated according to internal dose coefficients for Chinese reference adult male phantom and GB 18871-2002 were 0.26 mSv and 0.19 mSv, respectively. Based on the Chinese reference adult male phantom, the majority of the committed effective dose was attributed to ²¹⁰Pb (45.1%), ²²⁸Ra (37.1%), ²¹⁰Po (12.3%), and ²²⁶Ra (4.7%). Conclusion The levels of radionuclides in food in Beijing fluctuated within the background range, resulting in a low radiation dose burden to the population.

Objective To investigate the method of tube furnace oxidation combustion and liquid scintillation counting for the determination of carbon-14 in seafood, and to provide technical support for the monitoring of carbon-14 in seafood. Methods By studying the pyrolysis characteristics of five types of dried seafood samples, including yellow croaker, white shrimp, swimming crab, clam, and seaweed, a temperature control program suitable for the oxidation combustion of seafood was established. The combustion efficiency, carbon element recovery rate, and the accuracy and precision of the method were determined. Results The combustion efficiency was more than 98% for most seafood using the recommended combustion program. The recovery rate of carbon was similar to that calculated by glucose combustion; both were more than 95%. Four laboratories validated the accuracy of the method by measuring the carbon-14 activity concentration in the Chinese sugar carbon standard material. The relative errors ranged from 1.03% to 3.41% and the average relative error was 2.36%. The precision of this method was verified by measuring the carbon-14 activity concentration in yellow croaker samples. The within-laboratory relative standard deviation ranged from 5.11% to 9.35% and the between-laboratories relative standard deviation was 4.04%. Conclusion The tube furnace oxidation combustion and liquid scintillation counting method was used to determine the activity concentration of carbon-14 in seafood. The recommended oxidation combustion program is more targeted and less time-consuming. The accuracy and precision of this method meet the requirements. This method is suitable for the determination of carbon-14 in seafood.

Objective To track and evaluate the implementation of the Radiation Shielding Requirements in Room of Radiotherapy Installations—Part 1: General Principle (GBZ/T 201.1–2007) among relevant personnel in medical radiation institutions, and to provide a scientific basis for revising the standard. Methods According to the Guidelines for Health Standards Tracking Evaluation (WS/T 536–2017) and the implementation protocol of standard evaluation, an online survey was conducted among 212 relevant workers from 146 medical radiation institutions across 18 provinces in China. The data were aggregated and analyzed with the use of Microsoft Excel 2010. Results A total of 215 questionnaires were returned, of which 212 were valid. Among the valid respondents, 77.8% believe that this standard is universally applied; 96.2% believe that this standard can meet work needs; 63.7% have participated in relevant training on this standard; 74.1% use this standard once or more per year; and 10.8% believe that this standard needs to be revised. Conclusion Medial radiation workers have a high rate of awareness of the basic information and content of the standard, but the understanding and application of the standard content need to be improved. We recommend that relevant departments further strengthen the promotion of and training on the standard, revise some content based on actual situation, and improve workers’ ability to use the standard.

kV X-ray radiotherapy was the primary mode of radiotherapy widely used to treat many types of cancer, including deep tumors, before the invention of the Co-60 therapy machine and the electron linear accelerator, which gradually replaced kV X-ray radiotherapy. kV X-ray radiotherapy equipment requires less space and shielding, and still has application value in the treatment of skin lesions and superficial tumors. Especially in recent years, kV X-ray has been used in the treatment of keloid, and electronic brachytherapy equipment has been used in intracavitary, intraoperative, and superficial radiotherapy. Therefore, kV X-ray radiotherapy has seen renewed application. The quality control of kV X-ray radiotherapy equipment is the key to ensure the treatment effect and safety of patients. This paper reviews the current status of quality control of kV X-ray radiotherapy equipment and provides a reference for the formulation of quality control assessment standards for kV X-ray radiotherapy equipment.

Objective To compare the response capability of active personal dosimeters (APDs) in the pulse radiation field of interventional radiology, and to find APDs that can be used for dose optimization monitoring for interventional radiology staff. Methods Seven models of APDs and dose monitoring systems were tested in the following four types of radiation fields: continuous radiation field (Cs-137), single-pulse radiation field (80 kV, 10 mA, 10～1000 ms), multi-pulse standard radiation field (70 kV, 20～500 mA, 1～20 ms/pulse, frames per second 1～20), and multi-pulse scattering field (angiography machine, irradiation field: 15 cm × 15 cm, 22 cm × 22 cm, 27 cm × 27 cm, angiography: 65～74 kV, 6.2～8.2 mA; photography: 65 kV, 343～479 mA). Results All APDs showed good dose responses in the continuous radiation field. The ratio of the results obtained with and without phantom was 1～1.1. In the single-pulse radiation field, DMC3000 and TruDose showed good dose response, linearity, and repeatability. Under the main ray of the multi-pulse radiation field, DMC3000 and TruDose showed good dose response, linearity, and repeatability as the dose rate increased, and there were 5%～13% differences in the response ability between the two models. In angiography machine scattering field, the ratios of the results obtained from DMC3000, TruDose, and RaySafei3 to those from thermoluminescence dosimeter were 1.08 ± 0.09, 0.95 ± 0.11, and 1.13 ± 0.11, respectively. Conclusion DMC3000, TruDose, and RaySafei3 can be used in clinics as auxiliary dosimeters to optimize radiation dose monitoring and radiation protection measures for people at high risk of occupational diseases. Interventional radiology workers can implement actions to reduce the cumulative dose based on real-time dose information, thereby reducing the radiation dose.