Objective To explore dendritic cells (DCs)-mediated antigen presentation for radiation-injured cells by using the in vitro cell co-culture technology to simulate the in vivo microenvironment of the lung tissue. Methods ⁶⁰Co γ-irradiated mouse lung epithelial cells (MLE-12) were cultured with bone marrow-derived DCs and/or splenic T lymphocytes for 48 hours. Flow cytometry was used to measure the expression levels of costimulatory molecules (CD80/86) and antigenic peptide recognition complexes (the major histocompatibility complex [MHC] class Ⅰ/Ⅱ) on DCs and T cell activation markers (CD69/28/152) as well as the numbers of CD4⁺ and CD8⁺ T cells. Results ⁶⁰Co γ irradiation significantly increased the apoptosis rate of MLE-12 cells in a dose-dependent manner, and significantly stimulated the expression of CD80/86 and MHC Ⅱ on DCs, without direct activation of T cells. After γ (6 Gy)-irradiated MLE-12 cells were co-cultured with DCs and T lymphocytes for 48 h, there were significant increases in the expression of CD69 and CD28 on T cells, the numbers of CD4⁺ and CD8⁺ T cells, and the expression of CD86 and MHC I on DCs, as compared with the control groups. Conclusion Radiation-injured cells can stimulate antigen presentation by DCs and activate T cells.

Objective To investigate the radiation dose at the entrance of the accelerator treatment room, and to guide the radiation protection detection at the entrance of the treatment room. Methods The FLUKA program was used to build the model of accelerator head and treatment room. Under the simulation conditions of 10 MV and 600 cGy/min for the accelerator, the radiation dose rate inside the entrance of the treatment room was measured at different gantry angles, irradiation conditions, and labyrinths. Results The entrance dose rate with a water tank was significantly higher than that without a water tank under different inner labyrinth wall thicknesses and gantry angles. The entrance dose rate reached the maximum at the inner labyrinth wall thickness of 1800 mm and the gantry angle of 90°. When the inner labyrinth wall thickness was 1000 mm and the gantry angles were 0° and 180°, the entrance dose rate was significantly higher than that at other conditions. The dose rate at the entrance of the treatment room reached (82.26 ± 48.95) μSv/h to (314.09 ± 96.34) μSv/h under the following conditions: the inner labyrinth wall thickness of 1800 mm, the gantry angle of 90°, with a water tank, and the width of the inner labyrinth entrance of 1400-2200 mm. Conclusion The dose at the entrance of the accelerator treatment room mainly comes from the scattering and leakage radiation of the useful wire harness on the patient’s body surface, and the entrance dose rate increases with the increase in the width of the inner labyrinth entrance. In the entrance protection test, the gantry angle should be determined considering the inner labyrinth wall thickness, and the test should be performed at four angles in the uncertain case to ensure the comprehensiveness and accuracy of test results.

Objective To calculate the energy dependence of absorbed dose in EBT3 film, and to reveal the error in the measurement of proton absorbed dose by EBT3 film. Methods Beam energy was gradually increased in the clinical photon and proton energy ranges. Geant4 was used to calculate the difference in absorbed dose between EBT3 film and the same volume of water. The results were compared with the theoretical values. Results For photons and protons, the thresholds for absorbed dose with energy dependence were 100 keV and 11 MeV, respectively. The energy dependence was consistent with the theoretical values when the photon and proton energies were higher than the corresponding thresholds, and irrelevant to the theoretical values when energies were lower than the thresholds. The differences between the proton Bragg peak and 50% dose point and the actual positions were less than 1%. Conclusions For protons and photons with high energy, the energy dependence of absorbed dose in EBT3 film is negligible. For protons and photons with low energy, EBT3 film shows very different energy dependence of absorbed dose, which should be taken into consideration. The proton Bragg peak and 50% dose point measured by EBT3 film are basically the same as the actual positions.

China has a huge cumulative storage of NORM solid waste, which urgently needs to be treated and disposed of in a scientific and standard way. Through analyzing the current status and technologies of treatment and disposal of NORM solid waste and relevant environmental radiation protection regulations and standards, we put forward suggestions on the improvement of regulations and standards and the applicability of treatment and disposal technologies, to provide a reference for the green and sustainable development of mineral resources in China.

Objective To investigate the radionuclide radium-226 and natural uranium content in the main agricultural products around a decommissioned uranium tailings pondand to determine the radioactivity level in the food around the tailings pond. Methods From 2017 to 2021, several samples of rice and beans were collected in the surrounding area of the tailings pond for five consecutive years, and the concentrations of radium-226 and natural uranium were measured by a high-purity germanium gamma spectrometer. The annual accumulated effective dose of internal exposure caused by radium-226 ingested through local standard human diet was estimated by the indirect method. Results The detection rate of natural uranium in rice was 96.0%, and the detection rate of radium-226 was 74.0%; the detection rate of natural uranium in beans was 96.7%, and the detection rate of radium-226 was 73.3%. The annual accumulated effective dose caused by radium-226 ingested through diet was about 170.22 μSv/a in surrounding residents. Conclusion The concentrations of radium-226 and natural uranium in the main agricultural products around the tailings pond are within the limit of the national standard. By comparing with the research results in related fields in China, the radiation effects caused by radium-226 ingested through dieton the residents around the tailings pond are acceptable.

Objective To measure the specificactivity of natural and synthetic radionuclides in the environmental soil of Panjin, China and determine the content of radionuclides in the surface soil, and to conduct a scientific assessment of the radiation health risks of residents in this area. Methods Thirty-one surface soil samples were collected within the jurisdiction of Panjin, and a high-purity germanium detector was used for γ spectrum analysis to obtain the content of radionuclides and the current environmental radioactivity level. The two independent samples mean t-test was used to compare the specific activity data of radionuclides in soil samples between Panjin and Liaoning Province or China. Results The meanspecific activities of natural radionuclides ²³⁸U, ²²⁶Ra, ²³²Th, ⁴⁰K, and synthetic radionuclide ¹³⁷Cs in the surface soil samples of Panjin were 18.7 Bq/kg, 19.6 Bq/kg, 23.5 Bq/kg, 604.6 Bq/kg, and 0.9 Bq/kg, respectively. Conclusion The specific activities of natural and synthetic radionuclides in the surface soil samples of Panjin Area at the background level, causing a very low health risk to the people in this area.

Objective To solve the problem of fast locating primary radiation in dental panoramic tomography apparatus by designing a linear model-based positioning die body. Methods By applying the mathematical principle of solving the linear equation,the two-dimensional plane coordinates were mapped to the detector plane of dental panoramic tomography apparatus, and the horizontal coordinate position was determined by determining the vertical coordinate value through X-ray imaging in the detector plane. Finally, the position of primary radiation in the detector plane was determined. Results The longitudinal characteristics of the image were determined by analyzing the images taken after the application of the model, and the final position of the primary radiation in the detector plane was accurate. By comparing the detection results of die body method and film method, the localization results by the die body method fell within 90% of the image center by the film method. There was no significant difference in the localization results between the two methods by Shapiro-Wilk normality test and paired-samples t test (P > 0.05). Conclusion For narrow-beam devices, the positioning die body designed based on the linear model method can locate the position of the primary radiation in the detector plane quickly and effectively and replace the film method.

Objective To analyze the monitoring results of external exposure dose of interventional radiology staff in a tertiary general hospital in Beijing, China, 2018—2020, and to provide a basis for safe guarding staff health and hospital radiation protection management. Methods A total of 321 interventional radiology staff in a hospital in Beijing were selected to collect information on the types of interventional work, positions, and personal dose monitoring results in 2018—2020. The dose monitoring results were analyzed using SPSS 22.0. Results The effective monitoring rate for the three years was 78.82%, 81.65%, and 96.85%, respectively, showing an increasing trend (χ² _trend = 16.134, P < 0.001). The annual dose equivalent per capita was 0.142, 0.142, and 0.265 mSv, respectively. The annual dose equivalent per capita in 2020 was significantly higher than those in 2018 (H = 24.562, P < 0.001) and 2019 (H = 39.378, P < 0.001). The annual dose equivalent per capita in 2020 was in the order of interventional clinician > interventional nurse > technician (H = 10.699, 6.562, P < 0.01). The annual dose equivalent per capitain 2020 was higher in the cardiology interventional department than in the comprehensive interventional, neuro interventional, and vascular surgery departments (H = 35.530, 37.614, 35.496, P < 0.001). Conclusion The number of interventional radiology staff monitored from 2018 to 2020 increased year by year, so did the effective monitoring rate.The external exposure dose was at low levels, which generally meets the requirements of national occupational exposure limits. Training on radiation protection for interventional radiology staff should be further strengthened to raise awareness of radiation protection.

Objective To analyze the relevant measures of radiation protection for dental X-ray diagnostic projects in 44 dental clinics in Guangdong Province, China, and discuss common problems. Methods Based on the three principles of radiation protection, relevant laws, regulations and standards of the state, combined with field investigations and test results of radiation protection, the situation of radiation protection and management was analyzed. Results The layout of 56 dental diagnostic rooms in 44 clinics was (basically) reasonable. The protective performances and quality control tests of 56 dental X-ray diagnostic machines met the standard requirements, and the dose equivalent rate around 56 dental diagnostic rooms was from the background to 1.47 μSv/h, which met the national standard. The coincidence rates of ionizing radiation warning signs, working status indicator lights and door light interlocks, automatic door closing devices, power ventilation devices, and personal protective equipment were from 85.70% to 98.20%. The compliance rates of dental radiologists and full-time (part-time) administrative staffs, occupational health monitoring, management system related to radiation protection, and radiation health files were from 79.5% to 100.0%. Conclusion The current situation of radiation protection and management in the dental X-ray diagnostic room is good, and relevant national regulations and standards should be promulgated or improved to standardize the cone-beam CT quality control testing, dental clinic location requirements, and radiation staff configuration.

Objective To analyze the abnormality of radiation damage sensitive indices in radiation workers after operation of a third-generation nuclear power plant in Guangdong Province, China, and to provide a basis for promoting the occupational health management of radiation workers. Methods A two-way cohort study (2019—2021) was conducted to compare the radiation sensitive indices of occupational health examination in the exposed group (453 subjects) and the control group (160 subjects). Results In 2021, the free triiodothyronine (FT3) level of the exposed group was significantly higher than that of the control group [(5.57 ± 0.56) pmol/L vs (5.42 ± 0.60) pmol/L, t = 0.59, P < 0.05]. From 2019 to 2021, the exposed group showed significant changes in the average levels of platelet, hemoglobin, FT3, free thyroxine (FT4), and thyroid-stimulating hormone (P < 0.05); FT3 and FT4 first increased and then decreased, while TSH decreased continuously. Conclusion Long-term exposure to low-dose ionizing radiation from nuclear power plants can affect the platelet, hemoglobin, FT3, FT4, and thyroid-stimulating hormone of radiation workers, and the effect is relatively prominent on thyroid function by causing a tendency to hypothyroidism.