Objective To evaluate the implementation, application, problems, and suggestions associated with the WS 262-2017 Specification for Testing of Quality Control in γ-Ray Sources Afterloading Brachytherapy among radiation workers in Jiangsu Province, China, and to provide a scientific basis for further revision and implementation of this standard. Methods A questionnaire survey was conducted among employees of public and private institutions involved in radiation health technology services, radiation health supervision, and medical services in Jiangsu Province who carried out afterloading testing, supervision, and treatment. The survey primarily focused on the implementation status, technical content, and implementation effect of WS 262-2017, and the results were summarized and analyzed. Results A total of 185 valid questionnaires were collected, and 73.5% of the respondents were aware of the standard. Among the respondents who were aware of the standard, 29.4% did not participate in relevant training, and 41.2% did not use or infrequently used the standard. Moreover, 94.1% of survey respondents considered the standard to be scientifically robust and free of issues, 88.6% responded that the main technical content of the standard was highly operable, and 97.8% agreed that the main content of the standard was coordinated and consistent with relevant regulatory standards. In addition, 88.6%, 90.8%, and 87.0% of survey respondents reported that this standard provided significant assistance and played an important role in optimizing radiation protection, quality control and testing of radiation therapy equipment, and improving professional skills for technical personnel. Conclusion Radiation workers in Jiangsu Province have a high awareness rate of WS 262-2017 and believe that this standard is scientifically rigorous and plays an important role. There is no need for revision, but relevant departments should strengthen the promotion and training concerning the standard.

Objective To track and evaluate the scientificity, applicability, and operability of the current implementation of the Radiation Shielding Specifications for Radiotherapy Treatment Rooms—Part 2: Radiotherapy Room of Electron Linear Accelerators (GBZ/T 201.2—2011) among personnel in medical radiation technology service institutions, and to provide scientific evidence for further improvement of the standard. Methods Following the Guidelines for Health Standards Tracking Evaluation Work (WS/T 536—2017) and the project implementation plan, a survey was conducted among 140 personnel engaged in shielding testing and evaluation of electron linear accelerator rooms in medical radiation technology service institutions from 24 provinces in China. The methods of pre-investigation, on-site research, mailing, and email were used to collect data for analysis. Results Questionnaires were completed by 140 respondents from 98 medical radiation service institutions, including 63 public institutions and 77 private institutions. Of the surveyed individuals, 86.68% claimed to have a good or very good understanding of the standard, while only 64.3% had participated in training related to the standard. The survey indicated a low level of mastery of the standard content among the personnel and insufficient efforts in training and dissemination. Although only 3.57% of the respondents considered the existing standard to be inapplicable in the context of new radiotherapy equipment and technological advancements, 95.71%, 93.57%, and 96.43% believed that shielding calculation examples should be added for tomotherapy devices, CyberKnife systems, and ring accelerators with self-shielding bodies. Furthermore, 65% of the respondents felt that neutron shielding should be considered for 10 MV X-ray accelerator rooms. Conclusion The GBZ/T 201.2—2011 has been widely used for radiation protection in radiotherapy. However, it is imperative to update this standard. Additionally, due to the technical complexity of the standard, it can be challenging for professionals to fully understand and implement it. Therefore, publicity goals should be tailored to different groups and the training of key personnel should be strengthened. A nationwide communication and cooperation mechanism should be established to ensure uniform implementation of the standard.

Objective To obtain the peak skin dose (PSD) of patients with interventional cardiology procedures and to evaluate the risk of deterministic effects. Methods Gafchromic XR RV3 films were used in a Level A tertiary hospital in Beijing to measure the PSD of patients who underwent interventional cardiology procedures. The measurement focused on four common types of procedures, including coronary angiography, percutaneous transluminal coronary angioplasty, catheter radiofrequency ablation, and congenital heart disease. The films were scanned by EPSON EXPRESSION 10000XL and analyzed by FILM QA Pro^TM 2014 software. Results PSD was measured in 59 patients with interventional cardiology procedures, including 23 with coronary angiography, 21 with percutaneous transluminal coronary angioplasty, 9 with catheter radiofrequency ablation, and 6 with congenital heart disease. The seven patients with PSD ≥ 2 Gy all underwent percutaneous transluminal coronary angioplasty, one with PSD > 3 Gy and six with PSD < 2 Gy. Conclusion The PSD of some patients with interventional cardiology surgery exceeded the dose threshold of deterministic effects recommended by the ICRP 118. There is a risk of deterministic effects in interventional cardiology surgery, especially in patients with percutaneous transluminal coronary angioplasty.

Objective To investigate the natural penetrating radiation levels along the Qinghai-Tibet Railway, and to preliminarily evaluate the doses received by the railway employees and passengers. Methods Natural penetrating radiation was measured at 15 typical locations with different altitudes along the railway and in the carriages of a train from Lhasa to Xining using high-pressure ionization chamber RSS131, sodium iodide radiation dose rate meter MARS1561, and neutron ambient dose equivalent rate meter LB6411. Results The levels of terrestrial gamma radiation, cosmic ray ionization components, and neutron radiation were 21.5-246.6 nGy/h, 79.8-225.5 nGy/h, and 24.5-101 nSv/h, respectively. The effective dose of natural penetrating radiation received by passengers and crew on a train from Lhasa to Xining was 4.82 μSv. Conclusion Comparison with the empirical formula and verification of method reliability confirm the accuracy of the measurement. Our results provide a primary understanding of the radiation levels along the Qinghai-Tibet Railway and the radiation doses received by passengers, which can be used as a basis for the regulatory authorities.

Objective To assess the value of multimodal ultrasonography for diagnosing thyroid nodules—atypia of undetermined significance (AUS) of thyroid imaging reporting and data system (TI-RADS) categories 3 to 5. Methods A total of 90 AUS thyroid nodules in TI-RADS 3-5 categories from 88 patients underwent conventional ultrasonography, ultrasound elastography, superb microvascular imaging, and multimodal ultrasonography at the same time. With fine needle aspiration biopsy results as the gold standard, the methods were compared in terms of the sensitivity, specificity, accuracy, false positive rate (FPR), false negative rate (FNR), and area under the receiver operating characteristic curve (AUC) for diagnosing thyroid nodules. Results There were no significant differences between patients with benign and those with malignant thyroid nodules in terms of sex, age, and nodule locations (all P > 0.05), but the proportion of thyroid nodules ≤ 1 cm in diameter was significantly higher for malignant thyroid nodules than for benign thyroid nodules (χ²=9.610, P=0.002). Compared with benign nodules, malignant nodules were significantly more frequent to have low-level echoes or very low-level echoes, a blurred margin, a vertical diameter/horizontal diameter ratio of > 1, and microcalcifications or no calcifications (all P < 0.05). An ultrasound elastography score of ≥ 3 and type III vascularity on superb microvascular imaging indicated a higher possibility of malignant thyroid nodules (both P < 0.001). The multivariable logistic regression analysis showed that the size, echogenicity, margin, and vertical diameter/horizontal diameter ratio, and superb microvascular imaging type of thyroid nodules were not significant markers for benign or malignant thyroid nodules (all P > 0.05), while microcalcifications/no calcifications and an ultrasound elastography score of ≥ 3 were independent risk factors for malignant AUS nodules (both P < 0.05). The diagnostic sensitivity, specificity, accuracy, FPR, and FNR of conventional ultrasonography for AUS nodules were 91.30%, 71.40%, 62.70%, 28.60%, and 8.70%, respectively; the values for ultrasound elastography were 85.50%, 66.70%, 52.20%, 33.30%, and 14.50%, respectively; the values for superb microvascular imaging were 66.70%, 76.20%, 42.90%, 23.80%, and 33.30%, respectively; and the values for multimodal ultrasonography were 75.20%, 92.50%, 67.70%, 24.80%, and 7.50%, respectively. For distinguishing between benign and malignant AUS nodules, the AUC values of conventional ultrasonography, ultrasound elastography, superb microvascular imaging, and multimodal ultrasonography were 0.866, 0.745, 0.774, and 0.918, respectively. Conclusion Multimodal ultrasonography shows better diagnostic efficacy for AUS nodules of TI-RADS 3-5 compared with conventional ultrasonography, ultrasound elastography, and superb microvascular imaging, which can facilitate the malignancy risk stratification and management of AUS thyroid nodules.

Objective To address the radioactive contamination of wounds caused by transuranic nuclides, wound radiation imaging based on coded aperture imaging technology was investigated. Methods By simulating multiple source terms using Monte Carlo method, the differences in imaging performance between two image reconstruction algorithms under near-field conditions were compared. The effects of detector pixels and detection plane pixels on image resolution were investigated. Results The imaging system was simulated based on the designed dimensions. The simulated imaging field of view was 89.4 mm×89.4 mm and the simulated angular resolution was 1.98°. Based on the comparison of the average width at half height of the reconstructed point sources under different conditions, it was found that increasing the number of pixels in the detector and detection plane optimized the angular resolution but significantly prolonged the Monte Carlo simulation time. Conclusion According to the simulation results, the parameters of the imaging system can be used to effectively image radioactive contamination. Our results provide methodological support for the measurement of wound contamination caused by transuranic nuclides, and lay the foundation for the development of wound contamination imaging detection systems in the future.

Objective To study the shielding effect of the protective door of a maze-free debugging room for an 18 MV medical linear accelerator and its influencing factors, and to provide guidance for protection of debugging personal against radioactive occupational disease hazards. Methods The investigation focused on the protective door of a newly constructed maze-free debugging room for an 18 MV medical linear accelerator. The protective door was made of the following shielding materials from inside to outside: 2.5 cm steel plate + 20 cm lead + 41 cm polyethylene containing 5% boron + 6 cm lead + 2.5 cm steel plate. The right side of the protective door was provided with a groove (commonly known as “door pocket”) lap. With different lap widths, irradiation directions, and installation positions of the accelerator base, FLUKE451P and WENDI II neutron detectors were used to measure the ambient dose equivalent rate of the points of interest outside the protective door. The shielding effect and influencing factors were analyzed. Results When the lap width at both sides of the protective door was 300 mm, the ambient dose equivalent rates outside the protective door were (1.37 ±0.05) μSv/h on the side with “door pocket” and (4.71 ±0.11) and (4.19 ±0.11) μSv/h on the side without “door pocket”. When the primary beam of the accelerator was directed towards the east, the ambient dose equivalent rates at the points of interest outside the protective door were higher than those of the corresponding points of interest when the primary beam was directed towards other directions. When the accelerator base was located on the south side of the machine room, the ambient dose equivalent rates of the points of interest outside the protective door under the same irradiation conditions were lower than those when the accelerator base was located on the north side of the machine room. Conclusion The study of an 18 MV accelerator and its maze-free debugging room showed that the radiation of photons and neutrons should be taken into consideration when designing the protective door at the entrance. The protective door with shiplaps on both sides of the wall has improved shielding effect outside the door.

Objective To investigate the application efficiency and potential of CT radiomics in differentiating malignant and benign sub-centimeter solid pulmonary nodules. Methods A retrospective study was performed on the sub-centimeter ( ≤ 10 mm) solid pulmonary nodules detected by enhanced CT in our hospital from March 2020 to January 2023. Malignancy was confirmed by surgical pathology, and benignity was confirmed by surgical pathology or follow-up. Lesions were manually segmented and radiomic features were extracted. The feature dimension was reduced via feature correlation analysis and least absolute shrinkage and selection operator (LASSO). The 5-fold cross validation was used to validate the model. Support vector machine, logistic regression, linear classification support vector machine, gradient boosting, and random forest models were established for CT radiomics. Receiver operating characteristic curves were drawn. Delong test was used to compare the diagnostic performance of the five classifiers. The optimal model was selected and compared to radiologists with medium and high seniority. Results A total of 303 nodules, 136 of which were malignant, were examined. Radiomics models were established after feature extraction and selection. On test set, the areas under the receiver operating characteristic curves of support vector machine, logistic regression, linear classification support vector machine, random forest, and gradient boosting models were 0.922 (95%CI: 0.893, 0.950), 0.910 (95%CI: 0.878, 0.942), 0.905 (95%CI: 0.872, 0.938), 0.899 (95%CI: 0.865, 0.933), and 0.896 (95%CI: 0.862, 0.930), respectively. Delong test indicated no significant differences in the performance of the five radiomics models, and the support vector machine model showed the highest accuracy and F1 score. The support vector machine model showed significantly higher diagnostic accuracy as compared to radiologists (83.8% vs. 55.4%, P < 0.001). Conclusion The radiomics models achieved high diagnostic efficiency and may help to reduce the uncertainty in diagnosis of malignant and benign sub-centimeter solid nodules by radiologists.

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.

Objective To understand the effects of ²⁴¹Am standard material powder with different matrices on the determination of gross alpha activity in water, and to provide a reference for the selection and use of alpha standard sources. Methods The alpha counting efficiency of ²⁴¹Am standard material powder with different matrices was measured by low-background alpha and beta measuring instrument. The radiochemical recovery rate and whole process efficiency of gross alpha activity in water were determined by spike experiments. Results The alpha counting efficiency of the ²⁴¹Am standard material powder with four matrices was in the descending order of calcium carbonate, calcium carbonate and silica mixed matrix, calcium sulfate, and silica. The default chemical recovery rate is 1 when gross alpha activity in water is measured by thick source method. The use of ²⁴¹Am standard material with calcium carbonate as a matrix resulted in about 35% decrease in gross alpha activity, and about 10% deviation was observed using ²⁴¹Am standard material with silica or calcium carbonate and silica mixed matrices. The whole process efficiency of alpha activity in four spiked water samples with ²⁴¹Am standard solution and ²⁴¹Am standard material powder with calcium carbonate, silica, or mixed matrix was 6.34%-7.30%. Conclusion Standard materials with different matrices demonstrate different self-absorption of alpha particles and various influence on the chemical recovery. When purchasing and using standard material powders for alpha activity measurement in laboratories, the composition of the matrix should be clarified as much as possible, and the gross alpha activity in water should be determined by measuring the whole process efficiency if necessary.

Objective To assess the feasibility of employing chip resistors for retrospective dose reconstruction following nuclear accidents, to examine the effects of storage temperature and storage time on the optically stimulated luminescence (OSL) characteristics of the chip resistors, and to explore measures to mitigate these effects. Methods Chip resistors were analyzed using automated instruments for measuring thermoluminescence and OSL manufactured by Risø in Denmark with various parameters to understand the impact of storage temperature and storage time on OSL signals. Results The OSL signals of chip resistors exhibited exponential attenuation within 10 min after irradiation, and then stabilized (count change < 10%) within 2-7 days of storage. The chip resistors exhibited linear dose responses within 1-3 days of storage after 0.1-2 Gy irradiation. OSL signals diminished as the storage temperature increased. However, preheating at 130 ℃ for 1 min effectively eliminated the differences caused by temperatures between 25 ℃ and 45 ℃. Conclusion The OSL signals of chip resistors are influenced by storage temperature and storage time. When preheated at 130 ℃ for 1 min, chip resistors stored for 1-7 days and at 25-45 ℃ exhibited OSL signal errors of 10% or less. This result emphasizes the importance of preheating for measurements in practical applications, thus providing a scientific approach and a solid foundation for the use of chip resistors in retrospective dose reconstruction.

Objective To establish a method for quantitative analysis of tiny amounts of tritium in hydrogen below the detection limit of isotope ratio mass spectrometer. Methods Hydrogen was oxidized to produce water in a self-developed catalytic oxidation device filled with platinum hydrophobic catalyst. The effects of different experimental conditions on hydrogen conversion rate were investigated. The tritium concentration in the synthetic water was measured using a liquid scintillation counter. The tritium concentration in hydrogen was calculated according to the measurement of the synthetic water. Results When the flow rate of hydrogen was fixed, the conversion rate of hydrogen increased with the increase of the reaction temperature but increased and then decreased with the increase of the flow rate of oxygen. Hydrogen could be completely converted under optimal experimental conditions. The hydrogen samples with volumetric tritium concentrations in the range of 1×10^-7 to 2×10^-14 were converted to water at the reaction temperature of 110 ℃ and hydrogen/oxygen flow rate of 100 mL/min. The resulting water was measured using a liquid scintillation counter. The measurement accuracy was better than 2%. Conclusion This method can be used to measure hydrogen samples with tiny amounts of tritium below the detection limit of isotope ratio mass spectrometer. Our results provide data support for the calculation of the separation capacity of cryogenic distillation process.

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.

Objective To explore the radiosensitizing effect of arsenic trioxide (ATO) in cervical cancer, and to further explore the underlying mechanism related to DNA damage repair. Methods Human cervical cancer cells (Siha and Hela cells) were cultured in vitro, treated with different concentrations of ATO, and the cell proliferation was detected by CCK-8 assay. The cells were divided into four groups: control group, radiotherapy (IR) group, ATO group, and radiotherapy + ATO (IR + ATO) group. Radiosensitization ratio was determined by plate cloning assay, cell cycle and apoptosis by flow cytometry, the expression of γH2AX by immunofluorescence, the expression of Cyclin B1, PTEN, and RAD51 by Western blot, and the expression of RAD51 mRNA by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Results CCK-8 showed that ATO at concentrations of 1 μM and higher could significantly inhibit the proliferation of Siha and HeLa cells. Plate cloning showed that ATO had a radiosensitizing effect on cervical cancer, and the radiosensitization ratios were 1.37 and 1.30, respectively. Flow cytometry showed that the proportion of cell cycle arrest was significantly higher in the IR + ATO group than that in the control group (P < 0.001). The apoptosis rate was significantly higher in the IR + ATO group than that in the control group (P < 0.01). Western blotting showed that the expression levels of PTEN and RAD51 proteins significantly decreased (P < 0.05) and the expression level of Cyclin B1 protein significantly increased (P < 0.05) in the IR + ATO group. Conclusion ATO achieves radiosensitization in cervical cancer through blocking the DNA homologous recombination repair pathway by consuming PTEN.

Objective To evaluate the effects of radioactive impurity nuclides in ⁹⁰Y glass microsphere on therapeutic dose during radioembolization of pancreatic cancer. To provide a reference for correction of the dose calculated for individuals with different pancreatic tumors. Methods In this study, the radioactive impurity nuclide composition of ⁹⁰Y glass microsphere samples was analyzed to determine the source term of Monte Carlo calculation. Then, according to the PET/CT medical imaging data of pancreatic cancer patients, the three-dimensional modeling software Solidworks 2020 was used to construct the real and personalized digital human digestive system model of pancreatic cancer patients at a resolution showing the vascular distribution in pancreas and tumor. Finally, the Monte Carlo program GATE 8.2 was used to simulate the three-dimensional radiation dose fields of radioactive impurity nuclides ⁹¹Y and ⁶⁵Zn from ⁹⁰Y glass microspheres in various tissues and organs. The three-dimensional dose fields were visualized to analyze the influence of radioactive impurity nuclides on therapeutic dose. Results The three-dimensional radiation dose fields of ⁹¹Y and ⁶⁵Zn from ⁹⁰Y glass microspheres demonstrated two dose extreme points. The maximum dose value of ⁹¹Y to tissue was 0.272 mGy and the maximum dose value of ⁶⁵Zn to tissue was 9.34 μGy, with average statistical errors of less than 3.2%. Conclusion The impact of radioactive impurity nuclides ⁹¹Y and ⁶⁵Zn in 90Y glass microsphere sample on therapeutic dose is minimal and can be neglected.

Objective To calculate the absorbed dose of ⁹⁰Y TheraSphere in the pancreas and the surrounding sensitive organs after the administration in the treatment of pancreatic cancer through the establishment of an individual voxel model, and to provide technical support for the clinical application of ⁹⁰Y TheraSphere in the treatment of pancreatic cancer. Methods An individualized voxel model was constructed in Geant4 software based on the CT images of the patient. 12 monoenergetic electron specific absorption fractions (SAFs) in the range of 0.01 to 1 MeV were calculated and validated against the ICRP data. The model and method were used to calculate the absorbed doses in the target organs under uniform and nonuniform distribution of ⁹⁰Y microspheres in the pancreas. Results The relative errors between the SAF values calculated based on the individualized voxel model and the ICRP data after mass calibration were less than 3.89%. When ⁹⁰Y was uniformly distributed in the pancreas, the absorbed dose in the pancreas was 4.69×10^-7 Gy/Bq; the absorbed doses in the liver, kidneys, and spleen were 6.15×10^-12, 6×10^-12, and 1.65×10^-11 Gy/Bq, respectively. When ⁹⁰Y was distributed within the tumor, the absorbed dose in the tumor was 6.69×10^-6 Gy/Bq and the absorbed dose in normal pancreas was 5.72×10^-8 Gy/Bq. The fitted relationship between tumor volume V and administered activity A at the prescribed dose of 120 Gy was quadratic, with relatively low activity required for concentrated administration in the center of the tumor. Conclusion The Monte Carlo dose calculation method based on individual voxel model accurately predicted the absorbed doses in the surrounding sensitive organs (liver, kidneys, and spleen) when ⁹⁰Y TheraSphere was used to treat pancreatic cancer. These results and the analysis of the factors affecting the drug delivery activity will provide data support for the clinical research of ⁹⁰Y TheraSphere in pancreatic cancer.

Objective To further extend the application of coincidence summing correction factor transfer experiments through the analysis of relevant measurements. Methods The passive efficiency was simulated using BE5030 high-purity germanium (HPGe) γ-energy spectrometer equipped with LabSOCS, and the total efficiency was simulated using LabSOCS in GENIE 2000 spectrum analysis software, which was used for calculating the coincidence summing correction factor. The coincidence summing correction factor transfer experiments were performed using the measurements with the point source containing ¹³⁴Cs, ⁶⁰Co, and ¹³⁷Cs as well as the body source to obtain the coincidence summing correction factors of other HPGe γ-energy spectrometers. Results The coincidence summing correction factors for ¹³⁴Cs and ⁶⁰Co were obtained using the BE5030 γ-energy spectrum. In verification by certificate activity, the absolute value of the maximum deviation was within 3.53%. Using coincidence summing correction factor transfer experiments, these factors were transferred to other high-purity germanium γ spectrometers. In verification by certificate activity, the absolute value of the maximum deviation was within 5.86%. Conclusion The coincidence summing correction factors calculated using simulated total efficiency by calling LabSOCS in the GENIE 2000 spectrum analysis software are effective in correction, and can be used as correction factors in standard laboratories. Through coincidence summing correction factor transfer experiments, the coincidence summing correction of other high-purity germanium γ-energy spectrometers can be achieved, which broadens the application of coincidence summing correction method.

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 separation efficiency of three physical separation methods for gaseous ¹⁴C, namely membrane separation, adsorption separation, and low-temperature separation, to screen for the optimal separation method, and to provide a reference for the separation and enrichment of ¹⁴CO₂ in online monitoring of ¹⁴C. Methods The experimental plan was designed, and three devices were constructed for separation and purification experiments. The purity, recovery rate, and separation time of CO₂ separated by the three methods were analyzed. Results All the three methods achieved the separation of CO₂. Under certain conditions, 20 mL of sample gas was obtained. The separation time of membrane separation method was 0.5 hour, CO₂ gas with a sample purity of 0.0486%-0.0488%VOL was obtained, and the recovery rate was only 2.5%?12.7%. The separation time of MOF material adsorption separation method was 24?30 hours, CO₂ gas with a sample purity of 20.2%?47.5%VOL was obtained, and the recovery rate was 57.3%?63.2%. The separation time of low-temperature separation method was 3 hours, CO₂ gas with a sample purity of 96.0%?99.8%VOL was obtained, and the recovery rate was 81.5%?92.5%. Conclusion The purity and recovery rate of CO₂ with low-temperature separation method were higher compared to membrane separation method and MOF material adsorption separation method. The separation time of low-temperature separation method was moderate. The low-temperature separation method can provide a reference for the enrichment technology of ¹⁴C in the rapid measurement of gaseous ¹⁴C effluent.

Objective To understand the level of nuclear radiation knowledge and attitude towards nuclear power plant construction among health emergency personnel around a nuclear facility, to enhance public awareness and education targeted at these individuals, to increase confidence in the safety of nuclear power plants, and to aid health emergency response work. Methods In September 2022, following the survey plan developed by National Institute for Radiological Protection, China CDC, a survey was conducted using a questionnaire designed by the institute. The survey was conducted by filling online questionnaire by 238 individuals engaged in health emergency gathered at their working units, including designated centers for disease control, hospitals, and township health clinics at the municipal, county, and township levels. The collected data were analyzed by SPSS 22.0 statistical software. The categorical data were statistically described by proportion and subjected to chi-square test. The continuous data were described by $\bar{x} \pm s$ and subjected to correlation analysis using multiple linear regression. Results A total of 225 valid questionnaires were collected. The scores were relatively high for professional and technical personnel of radiation health protection agencies, personnel with postgraduate degrees, and male personnel, and their scores were 10.83 ±2.13, 12.4 ±1.67, and 10.48 ±2.8, respectively. Sex and education were the factors influencing the level of radiation knowledge (P < 0.05). Most of the respondents were very concerned and worried about the safety of nuclear power plants, supported the construction of nuclear power plants by the state but took a neutral attitude towards the construction of nuclear facilities in the local area, and showed high level of trust in the government and the authoritative media. Conclusion According to the characteristics of the health emergency personnel, different publicity and education methods and activities should be used to enhance understanding of radiation knowledge. The authoritative role of the government and the media should be emphasized to build confidence in the safety of nuclear power plants.

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.

As the clinically most common endocrine system disease, thyroid disorder is a global health problem characterized by high incidence and high disease burden. Currently, surgery remains the standard treatment of most thyroid cancers; however, active surveillance remains a feasible option for treatment of low-risk thyroid disorders. As the currently most widely used approach of thermal ablation, radiofrequency ablation is a safe and effective treatment for a variety of thyroid disorders. The review presents the advances in the efficacy and complications of radiofrequency ablation for treatment of benign thyroid nodules, follicular thyroid adenoma, and primary and recurrent thyroid cancers.

Objective To develop a large-volume sample cassette in the shape of a formalin cup suitable for portable HPGe γ spectrometer, to determine the detection limits of the cassette at different detection times through fresh sample measurements, and to provide a reference for responding to and monitoring of nuclear and radiation emergencies. Methods According to the formula for calculation of detection limit described in the GB/T 16145—2022, ¹³¹I and ¹³⁷Cs were measured using the sourceless efficiency calibration software Angle and the portable HPGe γ spectrometer for the optimization of the large-volume sample cassette. Fresh salmon samples were measured using a formalin cup-shaped large-volume sample cassette. The detection times were 2, 4, 6, 8, 10, 19, 19, 22, and 24 hours. The relationship between detection time and detection limit was assessed. Results Using sample cassettes with 15 cm radius and 10 L volume, the simulated detection efficiency of the formalin cup-shaped large-volume sample cassette was 30%-46% higher and the detection limit was lower as compared with the cake-shaped large-volume sample cassette. The detection limit obtained by measuring fresh salmon samples decreased with the extension of the detection time. These results provided a reference for the detection limits of measuring fresh samples for nuclides of concern in nuclear contaminated water with different detection times. Conclusion The formalin cup-shaped large-volume sample cassette developed by combining the optimization of detection limit provides a geometry for quantitative analysis in on-site monitoring of γ nuclides in the case of emergencies. Measurement of fresh samples using the cassette with different detection times showed that 8-10 hours of detection was optimal in balancing the detection limit and the detection time.

Conducting comprehensive and in-depth analysis, summarizing findings, and learning lessons from past accidents is a powerful means to prevent their recurrence. In this paper, we summarize a case of acute radioactive skin injury accident caused by industrial flaw inspection. We analyze the main causes of radiation accidents and discuss the problems existing in mobile radioactive source management from multiple perspectives. We put forward practical measures and suggestions to avoid or reduce the occurrence of similar accidents. Our findings contribute to the protection of the radiation health and safety of radiation workers and the public.

Objective To understand the levels and trends of personal doses of occupational external exposure among radiation workers in medical institutions in Huizhou City and to improve radiation protection management. Methods Thermoluminescent dosimetry was employed to monitor the personal doses of occupational external exposure of radiation workers over monitoring cycles spanning three months each. Results From 2019 to 2023, a total of 25 796 monitoring instances were recorded for radiation workers in medical institutions in Huizhou City. Diagnostic radiology workers accounted for the largest proportion of workforce in the occupational categories, followed by interventional radiology workers. The average annual effective dose per person ranged from 0.21 to 0.30 mSv, with an average of 0.26 mSv. The majority of annual effective dose per person was below 1.0 mSv, with no instances exceeding 20 mSv. Among all occupational categories, nuclear medicine workers had the highest average annual effective dose per person at 0.43 mSv, followed by interventional radiology workers at 0.37 mSv. There was a significant difference in the average annual effective dose per person among different occupational categories (P < 0.05), with nuclear medicine and interventional radiology workers having higher doses than workers in diagnostic radiology, dental radiology, and other applications (all P < 0.05). Conclusion The personal dose monitoring results for radiation workers in medical institutions in Huizhou City are at low levels, indicating that the radiation protection in the local medical institutions is sufficient and can effectively protect the occupational health of radiation workers.

Graduate education is critical for cultivation of high-level talents and promotion of technological innovation. Strengthening the management of graduate education is of great practical significance for ensuring and improving the quality of graduate education. The expansion of graduate education brings challenges to educational resources and management models, requiring research institutions to ensure educational quality and adapt to social needs. Based on the particularity of research institutes, this article takes the practice of radiation health graduate education as an example to explore the graduate student management elements of form teachers in research institutes. Our research provides a reference for improving the management level of graduate students in research institutes. Graduate form teachers are organizers, implementers, and mentors of graduate ideological education, academic culture, daily management, employment and entrepreneurship, and mental health education. They play an important role as a bridge and link in graduate education and cultivation. Faced with the challenges of graduate education in the new era, form teachers should continuously explore work methods that adapt to the needs of the era. They should also focus on reinforcing ideological and political theories, improving professional skills, establishing and improving management systems, and leveraging the role of student cadres to ensure the high-quality development of graduate education in research institutes.

Objective To evaluate the application of three deep learning algorithms in automatic segmentation of clinical target volumes (CTVs) in high-dose-rate brachytherapy after surgery for endometrial carcinoma. Methods A dataset comprising computed tomography scans from 306 post-surgery patients with endometrial carcinoma was divided into three subsets: 246 cases for training, 30 cases for validation, and 30 cases for testing. Three deep convolutional neural network models, 3D U-Net, 3D Res U-Net, and V-Net, were compared for CTV segmentation. Several commonly used quantitative metrics were employed, i.e., Dice similarity coefficient, Hausdorff distance, 95th percentile of Hausdorff distance, and Intersection over Union. Results During the testing phase, CTV segmentation with 3D U-Net, 3D Res U-Net, and V-Net showed a mean Dice similarity coefficient of 0.90 ± 0.07, 0.95 ± 0.06, and 0.95 ± 0.06, a mean Hausdorff distance of 2.51 ± 1.70, 0.96 ± 1.01, and 0.98 ± 0.95 mm, a mean 95th percentile of Hausdorff distance of 1.33 ± 1.02, 0.65 ± 0.91, and 0.40 ± 0.72 mm, and a mean Intersection over Union of 0.85 ± 0.11, 0.91 ± 0.09, and 0.92 ± 0.09, respectively. Segmentation based on V-Net was similarly to that performed by experienced radiation oncologists. The CTV segmentation time was < 3.2 s, which could save the work time of clinicians. Conclusion V-Net is better than other models in CTV segmentation as indicated by quantitative metrics and clinician assessment. Additionally, the method is highly consistent with the ground truth, reducing inter-doctor variability and treatment time.

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 explore the method for measurement of tritium in nuclear power plant liquid effluent purified by a mixed ion-exchange resin, to verify the feasibility of the method by experiments, and to provide technical support for the development of standard methods for the measurement of tritium in liquid effluent of nuclear power plants. Methods The purification effect of the mixed ion-exchange resin was determined by measuring the quenching factor, conductivity, and β-nuclide adsorption efficiency of the samples purified using the resin. A comparison was made between the ion-exchange resin method and the atmospheric distillation method for tritium determination. The precision and accuracy of the method were verified by calculating the relative standard deviation and the recovery in repeated measurement of samples with different activity concentrations and spiked samples. Results There were no significant differences in quenching factor, conductivity, and tritium activity concentration between the two methods. The adsorption efficiencies of EC20MB resin for common β-nuclides such as carbon, iron, nickel, strontium, yttrium, and cesium ranged from 99.28% to 99.88%. Repeated measurement of the same sample showed relative standard deviations of 5.2%-9.4% and recoveries of 86.8%-107%. Conclusion There were no significant differences between the results of the ion-exchange resin purification method and the atmospheric distillation method. The precision and accuracy of the method met the requirements of the ecological and environmental management authorities for monitoring tritium in liquid effluent from nuclear power plants. This method can be widely used in daily monitoring work.

Objective To measure the air-absorbed dose rate of gamma radiation in public areas for the situation of the local radiation environment. Methods Using a large-volume γ spectrometer system with a NaI(Tl) detector mounted on a UAV, we conducted large-scale airborne radiation monitoring in public areas in southwestern China, to measure the air-absorbed dose rate at a height of 1 m from the earth’s surface. Results The airborne radiation monitoring data were used to analyze the local radiation environment. The mean air-absorbed dose rate at a height of 1 m was 43.6 ± 12.9 nGy/h. Seven abnormal radiation points were detected, and two of them were located where construction was ongoing. At one of the abnormal radiation points, FH40G meter measurements showed that the air-absorbed dose rate at a height of 1 m was up to 22.0 μGy/h. Field soil samples were collected for HPGe γ spectrometer analysis: the ²³²Th radionuclide activity concentration was 96.0 kBq/kg, and the ²²⁶Ra radionuclide activity concentration was 9.9 kBq/kg. Conclusion Using the UAV-mounted large-volume γ spectrometer system with NaI(Tl) detectors for large-scale airborne monitoring is a fast and effective method for dragnet monitoring of the level of radiation in public areas.