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.

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 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 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 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.

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 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 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.

Objective To provide data base for the development of X-ray computed tomography (CT) diagnostic reference levels suitable for the physical characteristics of residents in Qingdao City, China. Methods A total of 3351 cases of adult CT scan data derived from 14 devices were randomly selected from three tertiary hospitals and one primary hospital from January 1 to December 31, 2022. CT examination was performed on the brain, paranasal sinus, neck, chest, abdomen, cervical vertebrae, and lumbar vertebrae. The cases also included CT angiography (CTA) data on the brain, neck artery, pulmonary artery, and aorta. The data types included tube voltage (kV), effective tube current (mAs), computed tomography dose index volume (CTDI_vol), and dose length product (DLP). The 1st, 2nd, 3rd quartile values of CTDI_vol and DLP were calculated. Results Large differences were observed in DLP among different body parts of adults. The DLP value showed a descending order of craniocerebral CTA, craniocerebral CT, abdomen CT, lumbar vertebral spiral CT, aorta CTA, pulmonary artery CTA, paranasal sinus CT, chest CT, cervical vertebral spiral CT, and neck CT. The 3rd quartile DLP values of the brain and neck were 657.9 and 228.1 mGy·cm, respectively. The CTDI_vol of the brain was largest (3rd quartile, 52.0 mGy) and the CTDI_vol of the chest was smallest (3rd quartile, 8.2 mGy). Conclusion There are significant differences in CTDI_vol and DLP between different body parts of adults in Qingdao City, and CT radiation dose levels are relatively low compared to other regions in China and other countries.

Objective To investigate the exposure level of radioactive hazard factors and the health management of radiation workers in non-medical radiation institutions (excluding military institutions) in Jinan, China through radioactive hazard factor monitoring, to identify the weak links, and to provide a scientific basis for future work priorities. Methods According to the monitoring plan formulated by Jinan Municipal Health Commission, the task undertaking institutions at all levels in Jinan investigated the types of radioactive hazard factors, detection, training, and health monitoring of 101 non-medical radiation institutions in Jinan. In addition, the workplace radiation levels were detected in 25 institutions of 6 types of monitoring objects, including industrial flaw detection, non-medical accelerator, non-sealed radioactive material workplace, nuclear instrument, baggage detector, and others. Results The investigation objects included institutions engaged in industrial flaw detection, nuclear instrument, luggage detector, non-medical accelerator, non-sealed source workplace, and others. Of these institutions, 91.84% were equipped with radiation protection detectors, 92.86% were equipped with personal dose alarm, 97.73% were equipped with personal protective equipment, 94.36% performed radiation protection training, 92.69% employed radiation workers with certificates, 95.77% performed personal dose detection, 94.83% performed occupational health examination, and 100.00% were qualified for radiation protection detection in workplace. Conclusion There is still a gap between the radiation protection status of non-medical institutions in Jinan and the national regulations and standards, so it is necessary to further strengthen supervision and law enforcement and make greater efforts in training and publicity.