Objective:To investigate the doses received by radiation workers from external and internal exposures during the production of 125I seed source, and to provide scientific basis for accurate evaluation of the annual doses of radiation workers. Methods:The production site and radiation workers of a 125I seed source production enterprise were determined as the survey objects. An AT1121 X/γ dosimeter was used to measure the ambient dose equivalent rate on the operation site such as welding and cleaning of the seed source, and the dose received by workers from external exposure was estimated. LiF (Mg, Cu, P) TLD dosimeters were used to measure the external doses to workers in a specific period. The doses obtained by the two method were compared and analyzed. The RG-50 air sampler and TC-30 iodine box were used to collect the workplace air, The activity concentration of 125I in the air was measured by using of the BE5030 high-purity germanium gamma spectrometer to estimate the internal dose to workers. The evaluation of doses was performed in accordance with the national standards GBZ 128-2019 and GBZ 129-2016. Results:The estimated annual dose to the worker′ hands is 24.5 mSv/year. The estimated maximum dose was 2.61 mSv/year. The maximum value of individual dose monitored was 2.42 mSv/year, basically consistent with the measured value on the basis of considering the actual work rotation. The maximum estimate of committed effective dose from internal exposure was 1.55 mSv, by a factor of up to 17 times the estimated external dose at the corresponding post.Conclusions:The radiation dose to the radiation workers’ hands is relatively high in the production of 125I seed source, so the protective measures for hands should be effectively strengthened. Meanwhile, the internal dose to the workers in the production process of 125I seed source should not be negelected. The ventilation of the site should be strengthened, the air flow direction should be planned, and the 125I activity concentration in the air should be regularly monitored.

Given the escalating number of cancer patients and the consequent rise in demand for radiation therapy in China, there is an urgent need to establish and improve a talent cultivation system for radiation dosimetrists. The United States, with an early-established cultivation system for radiation dosimetrists, boasts relatively mature and comprehensive systems of academic education and qualification certification. This study summarized and analyzed the educational and certification patterns for radiation dosimetrists in the United States based on public data from relevant institutions, related literature, and interviews with American radiation dosimetrists. Meanwhile, this study delved into and assessed the shortcomings in China′s radiation dosimetry education, examination, certification, and career advancement pathways. Furthermore, this study offered suggestions and recommendations for constructing a novel pattern tailored to the cultivation of radiation dosimetrists in China, in order to facilitate the high-quality development of the medical dosimetry discipline.

Radiation-induced adverse reactions in organs at risk(OAR) is recognized as a significant factor limiting doses to clinical target volumes(CTV). Magnetic ferrite nanoparticles, distinguished by their unique physicochemical properties such as ease of modification and high biocompatibility, have been extensively investigated in the biomedical field. This article reviews the latest advances in research on the application of magnetic ferrite nanoparticles in radiotherapy, focusing on their magnetothermal effect, dose enhancement effect, promotion of ferroptosis, regulation of the cell cycle, and improvement in image-guided quality. Furthermore, this article provides an outlook for future research.

With the widespread application of ionizing radiation in many industries and the construction of nuclear power plants, the potentials for nuclear accidents is also increasing. In the event of a nuclear accident, rapid classification of a large population is generally involved, so accurate estimation of the radiation dose to the exposed population is the primary task of nuclear emergency response. Based on this need, World Health Organization and International Atomic Energy Agency have each established a worldwide network of biological dosimetry laboratories. In addition, regional networks of biological dosimetry laboratories have been established in the European Union, North America, Latin America and Asia. Based on the long-term organization of national training and assessment of biological dose estimation technology, China will also establish its own network of biological dosimetry laboratories in the future to cope with the emergency disposal needs of potential nuclear accidents. In this paper, the international biodosimetry network and related work will be reviewed, and the idea of establishing biodosimetry laboratory network in China will be elaborated.

Objective:To investigate the efficacy of radiotherapy in postoperative metastatic human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer treated with pyrotinib, and to identify potential subgroups that may benefit from this strategy.Methods:The clinical data of 187 patients with postoperative distant metastatic HER2-overexpressing breast cancer who received pyrotinib at the First Affiliated Hospital of Bengbu Medical University from January 2018 to July 2022 were retrospectively analyzed. The Kaplan-Meier method was used to assess changes in survival outcomes in patients undergoing radiotherapy. Univariate and multivariate analyses were conducted to identify prognostic factors, and the log-rank test was used to determine potential subgroups that may benefit from radiotherapy.Results:Among the 187 patients, 76 received radiotherapy. The median follow-up duration for the entire population was 16.9 months (range: 3.1-37.9 months), and the 2-year overall survival (OS) was 75.0%. Multivariate analysis showed that age, metastatic status, and radiotherapy were independent factors affecting OS (3.86-6.76, P<0.05). Further subgroup analysis showed that radiotherapy significantly improved OS in patients aged ≥50 years, those with oligometastases or bone metastases, those not receiving endocrine therapy, and those resistant to trastuzumab ( P<0.05). Conclusions:Radiotherapy, in addition to pyrotinib, can enhance the survival rate of patients with postoperative metastatic HER2-overexpressing breast cancer. The benefits of radiotherapy may be more pronounced in patients with a low tumor burden, inadequate systemic treatment, and drug resistance.

Objective:To investigate the basic information of diagnostic and therapeutic nuclear medicine resources and practices in Henan province in 2022, and to assess the equity of their distribution, and to compare them with the 1998 survey result, so as to provide the reference for the allocation of nuclear medicine resources in Henan province.Methods:On-site investigations were conducted on medical institutions in Henan province that carry out diagnostic and therapeutic nuclear medicine practices. By using a combination of Lorenz curve, Gini coefficient and Theil index, the fairness of nuclear medicine resources and practices were assessed based on population distribution in Henan province in 1998 and 2022.Results:In 2022, there were 54 medical institutions in Henan province that carried out diagnostic and therapeutic nuclear medicine practices, with 67 items of nuclear medicine imaging and supporting equipment, and 690 nuclear medicine staff members involved. A total of 200 938 diagnostic clinical nuclear medicine imaging practices were performed throughout the year, with a diagnostic frequency of 2.04 per 1 000 population. Various types of therapeutic nuclear medicine practices were performed on 29 044 individuals, with a frequency of 0.29 per 1 000 population. The Gini coefficients for the distribution of diagnostic nuclear medicine practices, nuclear medicine staff, and practice frequency based on population distribution in Henan province in 1998 were 0.489, 0.505, and 0.526, respectively, and the Theil indices were 0.091 8, 0.172 1, and 0.139 7, respectively. The Gini coefficients for the distribution of nuclear diagnostic medicine equipment, nuclear medicine staff, and practice frequency based on population distribution in Henan province in 2022 were 0.244, 0.246, and 0.363, respectively, and the Theil indices were 0.086 8, 0.145 3, and 0.159 9, respectively.Conclusions:While clinical nuclear medicine in Henan province is rapidly developing, the distribution of various types of nuclear medicine resources and practices is becoming increasingly balanced. However, there still exists a certain degree of imbalance. Additionally, this also demonstrates a correlation between the resource distribution and regional economic development. The rationality of resource allocation needs further optimization.

Objective:To investigate the relationship between artificial radionuclide 137Cs and stable cesium (Cs) in wild edible fungi and seek potential correlations. Methods:A total of 30 samples, including the caps (with gills) and stipes of wild edible fungi, were collected from the northeastern region of China. The measurement and analysis of 137Cs were conducted following recommended procedures in GB/T 16145-2022, and stable Cs was determined using inductively coupled plasma mass spectrometry (ICP-MS). Then, the correlation analysis of data on 137Cs and stable Cs was performed using SPSS 11.5 software, and scatter plots were prepared using the Origin 21.0 software. Results:The fungi caps exhibited a specific activity of 137Cs ranging from 0.52 to 55.9 Bq/kg (dry weight) and a stable Cs content from 0.069 mg/kg to 16.2 mg/kg (dry weight). The stipes showed a specific activity of 137Cs ranging from 0.53 Bq/kg to 101 Bq/kg (dry weight) and a stable Cs content from 0.075 to 11.5 mg/kg (dry weight). These data revealed a significant correlation between the specific activity of 137Cs and the stable cesium content in all samples including caps and stipes, with correlation coefficients r of 0.956, 0.912, and 0.931, respectively, and all significant levels P < 0.01. The ratios of the specific activity of 137Cs to stable Cs content varied from 2.09 Bq/kg to 20.1 Bq/kg (dry weight), with an average of 10.7 Bq/kg (dry weight). Conclusions:Wild edible fungi fail to distinguish between 137Cs and stable cesium when absorbing Cs elements from their growing substrates. Furthermore, there is a strong correlation between the specific activity of 137Cs and stable Cs content. In the case of exogenous 137Cs contamination, the ratio of the specific activity of 137Cs and stable Cs content will significantly change. Therefore, an increase in the ratio can be used as a reference for identifying 137Cs contamination events.

Objective:To explore the dosimetry optimization strategy based on filter thickness and shape selection for the bulb superficial X-ray radiotherapy unit.Methods:Monte Carlo code TOPAS was used to model tubular equipment, and the dose distribution from six X-ray energies (50-150 kV) and five conventional aluminum filters (0.5-3.0 mm) with different thickness were simulated in the water model. The percentage depth dose (PDD) curve along the central axis, the center-axis profile dose at different depths, and the lateral dose distribution were analyzed. The dose distribution of three different designs of aluminum filters (conventional cylindrical, conical and oblique cylindrical filters) was compared to evaluate the effect of dosimetric optimization of different filter shapes.Results:Under the same energy, increasing the thickness of the filter can optimize the superficial skin dose, and the optimization effect of depth dose uniformity can be increased by 26% at a depth of 5.5 mm at 70 kV energy. The raised, flat and inclined dose distribution modes can be achieved by using conventional cylindrical, conical and inclined aluminum filters.Conclusions:By selecting the appropriate X-ray energy and filter thickness, an ideal dose distribution matching the tumor depth can be achieved. The application of personalized filters is also of great significance for diverse target areas.

Objective:To develop a method of employing flow cytometry to directly detect the γ-H2AX expression levels in peripheral blood lymphocytes of mice through fixation and lysis and to evaluate the feasibility of applying this method to research on the radiation-related biological effects and the efficacy evaluation of radioprotective drugs.Methods:A total of 41 male C57BL/6J mice were used. First, 21 mice were randomly divided into 7 groups according to different radiation doses (0, 1, 2, 4, 6, 8, and 10 Gy) with 3 mice in each group. Blood samples were collected from the tail vein of mice at 1, 4, 8, and 24 h after irradiation and immediately fixed with formaldehyde. Red blood cells (RBC) were lysed with Triton X-100, and γ-H2AX was labeled with specific antibodies. DRAQ5 dye was used to further exclude debris and anucleate cells. The mean fluorescence intensity of γ-H2AX in lymphocyte populations was directly analyzed by flow cytometry through forward and side scatter, and dose-effect curves after irradiation were established. Then, the other 20 mice were divided into radiation alone groups and radiation combined with WR-2721 administration groups at 4 and 6 Gy, respectively, with 5 mice in each group. Blood samples were collected from the tail vein of mice at 1, 4, 8, and 24 h after irradiation to detect the average fluorescence intensity of γ-H2AX in lymphocytes, which was used to evaluate the degree of DNA damage in mice and the therapeutic effect of WR-2721.Results:The expression of γ-H2AX in peripheral blood lymphocytes of mice significantly increased with the increase of radiation doses, and reached a peak at 1-2 h and then decreased. The dose-effect relationship was significant ( R2 = 0.9914). At 24 h after 4 and 6 Gy irradiation, compared with the radiation alone groups, the average fluorescence intensity of γ-H2AX in the radiation combined with WR-2721 administration groups was lower (144.8 ± 8.0 and 109.5 ± 9.7, vs. 178.0 ± 18.5 and 136.6 ± 5.4), with statistically significant difference ( t = 3.78, 5.48, P < 0.05). The average fluorescence intensity of γ-H2AX at 24 h after irradiation was consistent with the lowest values of the three blood cell lines at 7 or 14 d after irradiation. Conclusions:The application of flow cytometry with a fixation/dissolution protocol to directly detect the mean fluorescence intensity of γ-H2AX in peripheral blood lymphocytes of mice has significant application value in radiation biology effect research, radiation protection drug screening, and efficacy evaluation.

Objective:To investigate the effect of nuclide distribution with time from the in vivo metabolism based on measurement of radioactive contamination using lung counting method. Methods:The distribution of nuclides in the body with time was calculated on a basis of a single inhalation of aerosols containing 235U and the International Commission of Radiological Protection(ICRP) nuclide metabolism compartment model. A passive efficiency calibration of the lung counter, was performed using the simulation and calculation software Geant4 to obtain the contribution of the tissue or organs of interest to the lung counter, and to investigate the effect of the nuclide distribution on the lung counting method. Results:The time elapsed after inhalation of radionuclides, as well as their physicochemical state, has the effect on their distribution in the body and on the detection efficiency of the lung counter. Radionuclides with smaller particulate sizes have a higher initial retention in the lungs, and those with an activity median aerodynamic diameter (ADAM) of 1 μm contributed more fraction to the lung counter than those with an ADAM of 5 μm. F-type compounds were metabolized more rapidly by the respiratory system, and after 8 h of ingestion, nuclides were distributed in the lungs. F-type compounds were metabolized in the respiratory system at a relatively fast rate, and 8 h after inhalation, the fraction of nuclides retained in the lung contributed no more than 30% to the lung counter. Within 3 d after ingestion of M-type and S-type compounds, radioactive particulats largely deposites in the nasopharyngeal region. With biological metabolization and clearance, the fraction contributed by lung to counter is in rising, and the fraction to the lung counter typically remained larger than 80% after 3 d.Conclusions:Radionuclide metabolization in the body varies with their physicochemical properties and measurement time and site. For estimating internal contamination, consideration should be given to the distribution of nuclides, in order to avoid the overestimation.