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Design and test of proportional counter for measurement of tritium in air

Yang LYU ; Baoji ZHU ; Yuanqiao LI ; Xiaoxia LYU ; Heng ZHU ; Lijun XU ; Min LIN

Chinese Journal of Radiological Health.2024;33(6):626-630. doi:10.13491/j.issn.1004-714X.2024.06.002

Objective Ionization chamber detector is commonly used for direct and continuous measurement of tritium concentration in the air. However, the measurement sensitivity is low due to the limitations of weak current measurement technology. It is necessary to develop a proportional counter for measuring tritium in the air. Methods This study involved the design of a proportional counter, considering various factors such as materials and structure. The stability, plateau curve, detection efficiency, and energy spectrum of the counter were tested. Results The coefficient of variation of the proportional counter was 3.14%, which met the standard requirement of being less than 15%. The plateau length was 260 V and the plateau slope was 0.80%/100V, which met the requirement of being less than 1%/100V. The tritium detection efficiency reached 68.02%. The energy spectrum measurement indicated a significant difference between tritium signal generated by the proportional counter and background signal, and the distribution of tritium in the energy spectrum was more concentrated. The background counting rate during tritium gas activity measurement could be reduced through energy spectrum measurement. Conclusion The proportional counter can provide a reference for the direct and continuous measurement of tritium in the air.

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Calculation of retention and excretion fractions for uranium intake via wounds based on ICRP Report 137

Jieying LEI ; Yang ZHANG ; Bin ZHANG ; Ming XU ; Wei SHENG ; Gaofeng SUN

Chinese Journal of Radiological Health.2024;33(6):631-637. doi:10.13491/j.issn.1004-714X.2024.06.003

Objective To assess the retention and excretion fractions for uranium intake via wounds in the organs of adult reference computational phantom, and to improve the evaluation of health risks associated with radioactive isotopes intake via wounds. Methods A software for evaluation of the internal radiation dose was developed by combining the wound model in International Commission on Radiological Protection Report 156 and the systemic models in the International Commission on Radiological Protection Report 130 and the subsequent Occupational Intakes of Radionuclides series reports. This study was conducted to calculate the uranium retention fractions in adult reference individuals following ingestion through wounds of seven categories of uranium: weakly retained, moderately retained, strongly retained, very strongly retained, colloids, particles, and fragments. We assessed the retention fractions in the wound sites, bones, and liver, as well as the excretion fractions in urine and feces, and compared these results with authoritative results. Results The retention and excretion fractions of ²³⁸U and ²³⁵U in different forms of intake via wounds showed consistent variations. The retention fractions of weak and moderate uranium in wounds could be ignored after 1 000 d. The retention fractions of strong, avid, and colloid uranium were 10⁻⁴ to 10⁻⁵ after 10 000 d. A significant portion of the uranium present in the forms of particles and fragments exhibited long-term retention in wounds. The bone retention fractions were 1 to 2 orders of magnitude higher than the liver retention fractions. Following the intake of soluble and insoluble uranium, the retention fractions in these two organs decreased and increased, respectively, compared with those observed on the first day. The urinary excretion fractions were approximately 2 orders of magnitude higher than the fecal excretion fractions. Following the intake of soluble and particulate uranium, the excretion fractions decreased. At 1 000 d after the intake of uranium in the form of fragments, the urinary and fecal excretion fractions were 10⁻⁶ and 10⁻⁸, respectively. Conclusion The calculation results validated the accuracy of the established models, providing data support for the assessment of internal exposure doses in individuals following uranium wound contamination incidents.

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Comparison of accumulation and continuation methods in indoor radon measurement

Shanshan KOU ; Changsong HOU ; Yanchao SONG ; Haoran SUN ; Hongxing CUI ; Bing SHANG ; Yunyun WU

Chinese Journal of Radiological Health.2024;33(6):638-641. doi:10.13491/j.issn.1004-714X.2024.06.004

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.

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Design of a new full-face respiratory protection mask for on-site use at nuclear facilities

Yansong SUN ; Yi HAN ; Guodong LI ; Jinzhong ZENG ; Jie LIU ; Changbin DU ; Xiaomiao CHI ; Zhiwei CHEN ; Junjie JI ; Qinjian CAO

Chinese Journal of Radiological Health.2024;33(6):642-648. doi:10.13491/j.issn.1004-714X.2024.06.005

Objective Developing a new type of full-face respiratory protective mask for nuclear facility sites to enhance the sound transmission function and improve the facial adaptability. Methods Combined with feedback from on-site practical needs, this study utilized finite element simulation and ergonomic design methods to investigate the voice transmission units of full-face masks and the facial features of workers at key nuclear facilities. Based on the research results, a new full-face respiratory protection mask structure was designed. Results The optimized structure of passive thin film voice transmission unit significantly enhanced voice transmission efficiency, reducing average voice transmission loss by approximately 70% compared to the control group using thin plate units of equivalent thickness. The existing facial feature test panels insufficiently cover and unevenly classify the facial features of workers at key nuclear facilities. In this study, a specialized test panel based on measurement data achieved a total coverage of 98.5% with high distribution uniformity within each class, providing effective guidance for redesigning full-face mask structural parameters. In comparison to foreign products currently utilized in nuclear facilities, the newly designed full-face mask structure exhibited excellent tightness and structural safety and reliability, and can be cleaned, decontaminated, and reused. Conclusion The results of this study provide significant guidance for improving and optimizing full-face respiratory protection mask used at nuclear facilities, as well as promoting domestic production of high-quality full-face respiratory protection masks.

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Investigation and analysis of external exposure levels of radiation workers in selected veterinary clinics in China, 2022

Shuxia HAO ; Haitao YU ; Mengxue LI ; Shengnan FAN ; Tuo WANG ; Jingguo ZHANG ; Jun DENG

Chinese Journal of Radiological Health.2024;33(6):649-653. doi:10.13491/j.issn.1004-714X.2024.06.006

Objective With the increase in pet-owning households in China, veterinary clinics have increased at an annual rate of 19.86%. However, the management blind area that may exist in multi-department supervision has led to a significantly worse working environment of radiation workers in veterinary clinics than that of medical institutions. The purpose of this study was to understand the levels of occupational external exposure of radiation workers in veterinary clinics in China, analyze the occupational risks faced by radiation workers in veterinary clinics, contribute to the protection of the occupational health of radiation workers, and provide data and scientific basis for the formulation of national relevant regulations and standards. Methods The individual dose monitoring data of radiation workers in selected veterinary clinics in 2022 were obtained from the National Individual Dose Registration System. Results This study involved 1868 radiation workers from 1216 veterinary clinics in 28 provinces and municipalities in China. The maximum annual effective dose was 8.93 mSv, the annual collective dose was 536.77 man·mSv, the average annual effective dose was 0.29 mSv, and the median was 0.15 mSv. The largest proportion of individuals (94.5%) received a dose of less than 1.0 mSv, while 5.4% had doses ranging from 1.0 mSv to less than 5.0 mSv. For radiation workers with an annual effective dose of 1.0 mSv and above, the individual distribution ratio of radiation workers in veterinary clinics was significantly higher compared with those in medical institutions and industrial applications (P < 0.05). Conclusion The levels of occupational external exposure of radiation workers in veterinary clinics meet the requirements of national standards. However, attention should still be paid to the radiation protection of radiation workers in veterinary clinics. This includes enhancing the responsibility awareness of veterinary clinic owners, strengthening protection training for radiation workers, protecting the occupational health of practitioners, and preventing the occurrence of occupational radiation diseases.

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Investigation of gross α and gross β radioactivity and estimation of annual effective dose in drinking water from Dongjiang River in Dongguan City, China

Xing HUANG ; Huipeng CHEN ; Zhanhui LIANG

Chinese Journal of Radiological Health.2024;33(6):654-658. doi:10.13491/j.issn.1004-714X.2024.06.007

Objective To investigate the gross α and gross β radioactivity in Dongjiang River during high and low flow periods in Dongguan City, China, and evaluate the radiation safety status of Dongjiang River as a source of drinking water. Methods The gross α and gross β radioactivity levels were measured in the source water, treated water, and tap water from eight water treatment plants along the Dongjiang River, which relied on Dongjiang River water as their source, during both high and low flow periods. The annual internal effective dose from consuming Dongjiang River water was estimated. Results In high flow period, the gross α and gross β radioactivity levels were 0.016-0.041 and 0.063-0.140 Bq/L for source water, 0.011-0.039 and 0.064-0.131 Bq/L for treated water, and 0.013-0.024 and 0.078-0.127 Bq/L for tap water. In low flow period, the gross α and gross β radioactivity levels were 0.012-0.029 and 0.055-0.141 Bq/L for source water, 0.012-0.019 and 0.054-0.124 Bq/L for treated water, and 0.012-0.024 and 0.083-0.134 Bq/L for tap water. The estimated total effective doses of gross α and gross β radioactivity caused by consumption of water from Dongjiang River were 3.6 and 0.48 μSv/a, respectively. Conclusion The gross α and gross β radioactivity levels of water from Dongjiang River in Dongguan City are below the radioactive indicator values specified in the Standards for Drinking Water Quality (GB 5749-2022), remaining within the range of natural environmental background. The annual internal effective dose caused by consumption of water from Dongjiang River is below the individual dose limit set in the Guidelines for Drinking Water Quality.

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Investigation and analysis of external radiation dose and physical and mental health status of radiation workers in medical institutions

Dinghao JI ; Yezhong YANG ; Na LI ; Xiadong WANG ; Zhen SUN ; Rui ZHANG ; Yajie NAN

Chinese Journal of Radiological Health.2024;33(6):659-666. doi:10.13491/j.issn.1004-714X.2024.06.008

Objective To investigate the external radiation doses and occupational health examination data of radiation workers in medical institutions in Zhangjiagang City, China, explore the effects of long-term exposure to low-dose ionizing radiation on their health, and provide a reference for occupational health monitoring. Methods The radiation workers of medical institutions in Zhangjiagang City were selected as the research subjects. Their personal radiation doses and occupational health examination data were collected. A scale was used for mental health survey. The data were analyzed according to different clinical characteristic groups. Results During the 5-year period from 2019 to 2023, the average annual radiation dose received by radiation workers in medical institutions in Zhangjiagang City was 0.21 mSv/year. There were significant differences in the average annual radiation dose across these years and radiation workers with different occupations. The results of occupational health examinations showed significant difference in the total abnormal detection rate among these years (P < 0.01). There were significant differences in the abnormal rates of blood pressure, blood routine, and electrocardiogram across these years (P < 0.05). There were significant differences in the abnormal rate of routine blood test in radiation workers with different sexes, years of service, and radiation occupations (P < 0.01). There were significant differences in the abnormal rate of blood pressure in radiation workers with different sexes, ages, and years of service (P < 0.01). The mental health survey showed significant differences between the radiation and the non-radiation groups in terms of occupational stress, anxiety score, and depression score (P < 0.05). Conclusion Long-term low-dose ionizing radiation may have adverse effects on the physical and mental health of radiation workers, and it is necessary to strengthen the occupational health examination and radiation protection of radiation workers.

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A pilot survey of radiation doses for pediatric cardiac interventional procedures in two medical institutions in Beijing, China

Jielin QIN ; Hui XU ; Zechen FENG ; Limeng CUI ; Qiaoqiao ZHAO

Chinese Journal of Radiological Health.2024;33(6):667-674. doi:10.13491/j.issn.1004-714X.2024.06.009

Objective To understand the types, proportions, and radiation dose levels of pediatric cardiac interventional procedures. Methods A retrospective analysis was conducted using the basic information and radiation dose data from all cases of pediatric cardiac interventional procedures performed at two tertiary medical institutions in Beijing from July 2023 to August 2024. The data included air kerma-area product, reference point air kerma, and fluoroscopy time. Descriptive statistical analysis was conducted to evaluate the basic information and dosimetric indicators of the procedures. Non-parametric tests were employed to examine the differences between variables, and Spearman’s correlation coefficient was utilized to investigate the relationships among various factors. All cases were categorized into the diagnostic group and the therapeutic group. In the diagnostic group, the majority of procedures involved catheter examinations and angiography for identifying the type of disease. In the therapeutic group, the primary procedures included patent ductus arteriosus, atrial septal defect, ventricular septal defect, patent foramen ovale, pulmonary stenosis, radiofrequency catheter ablation, major aortopulmonary collateral arteries, complex congenital heart diseases, and other interventional procedures. Results The survey comprised 1008 cardiac interventional procedures involving 476 males and 532 females. The ages of the participants ranged from 0 to 15 years and the body weights from 4.5 to 105 kg. Among these participants, 92 and 916 were classified in the diagnostic and therapeutic groups, respectively. The proportions of interventional procedures were in the order of atrial septal defect (36.9%), radiofrequency catheter ablation (22.3%), patent ductus arteriosus (15.1%), complex congenital heart disease (4.8%), patent foramen ovale (3.1%), pulmonary stenosis (3.1%), ventricular septal defect (2.2%), other procedures (2.0%), and major aortopulmonary collateral arteries (1.5%). The radiation doses of different interventional procedures were statistically different (P < 0.05), with air kerma-area product ranging from 0.02 to 658.4 Gy·cm², reference point air kerma from 0.1 to 2524 mGy, and fluoroscopy time from 0.2 to 62 min. Conclusion In pediatric cardiac interventional procedures, there is considerable variability in radiation doses for the same type of procedure. Additionally, radiation doses for identical procedures vary between different medical institutions, and a few cases carry a risk of deterministic effects.

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Analysis of issues in quality control test results of linear accelerators in China

Hongbo WANG ; Xuexia LIU ; Songhui ZHANG ; Chenxu HUANG ; Yuexin GUO ; Quanfu SUN

Chinese Journal of Radiological Health.2024;33(6):675-680. doi:10.13491/j.issn.1004-714X.2024.06.010

Objective To study the unqualified items in the reported quality control tests of linear accelerators, analyze the issues in quality control tests, and propose the key points and development directions for accelerator quality control test in China. Methods A literature review was conducted using the CNKI database to analyze the qualified rates of test items and the issues in quality control tests. Results In the literature on the quality control tests of linear accelerators, except for a few provinces where the qualified rates of all test items were 100%, unqualified items were reported in most of the literature. There were unqualified items related to X-ray and electron beam in different reports. Error of dose indication was the unqualified item with the highest occurrence rate in X-ray test, and the item with the lowest qualified rates in X-ray and electron beam tests. The lowest qualified rate of X-ray dose indication error was 73.5% in 2016, and the lowest qualified rate of electron beam dose indication error was 46.2% in 2017. Conclusion Tests should be carried out strictly according to the items and intervals specified by the quality control test standards. Hospitals, radiation health technology service institutions, and health administrative departments should each fulfill their respective responsibilities, work together, and place emphasis on ensuring effective quality control tests of linear accelerators to further enhance the overall quality control standards for these devices.

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Analysis of issues and lessons learned from emergency evacuations in three major nuclear accidents

Penglei HU ; Huifang CHEN ; Long YUAN ; Ximing FU ; Cuiping LEI

Chinese Journal of Radiological Health.2024;33(6):681-685. doi:10.13491/j.issn.1004-714X.2024.06.011

After the Three Mile Island, Chernobyl, and Fukushima nuclear accidents, numerous issues were exposed during the emergency evacuation process, such as insufficiently detailed emergency plans, lack of specific evacuation route schemes, inadequate preparation of emergency protective materials, and delays in emergency response decision-making. Additionally, these accidents revealed serious issues with the emergency evacuation of vulnerable populations. In particular, during the Fukushima nuclear accident, the lack of resource support led to deteriorating health and fatalities among hospital patients and elderly residents in nursing homes near the nuclear power plant during emergency evacuation. To learn from the experiences and lessons of public protection actions in emergency evacuations during major nuclear accidents, the government should enhance the guidance of nuclear emergency evacuation plans, increase the quality of emergency training and exercises, and improve their specificity and continuity, as well as establish an efficient nuclear emergency rescue response and decision-making mechanism. For vulnerable populations in nuclear emergency evacuations, the government should consider updating the nuclear emergency plans and disaster preparedness material reserves of medical facilities (such as designated treatment hospitals) and elderly facilities (such as nursing homes) within the emergency protection action areas of nuclear power plants in a timely manner. This will ensure that these institutions have the capacity to provide initial evacuation and necessary support for vulnerable populations in disaster situations.

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