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Objective To preliminarily compare 6LiF-7LiF and CR39 in individual neutron dose monitoring, and to provide a reference for improving individual neutron dose monitoring. Methods According to the GBZ 128-2019, 26 radiation workers from 7 institutions received individual neutron dose monitoring with 6LiF-7LiF and CR39 at the same time. The monitoring results were analyzed. Results For most of the workers, the personal neutron dose equivalent Hp(10) was less than the minimum detectable level. The results with the two monitoring methods differed in 6 of 26 workers. Conclusion Both 6LiF-7LiF and CR39 monitoring methods can be used for individual neutron dose monitoring for radiation workers, but the difference between 6LiF-7LiF and CR39 (in threshold energy, energy response, etc.) should be considered so that different types of radiation workers receive appropriate individual neutron dose monitoring.
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Objective To investigate the awareness, implementation, and application of the Radiation Shielding Specification for Radiotherapy Room, Part 3: Radiotherapy Room of γ-Ray Sources (GBZ/T201.3—2014) by medical institution personnel, to collect problems and recommendations, and to provide a scientific basis for further amendments and implementation of the standard. Methods A questionnaire survey about the awareness, training and application situation and the modification advices of the standard was conducted among practitioners engaged in the production, use, and machine room design related to γ-ray source radiotherapy equipment (collectively referred to as medical institution personnel) in 12 provinces and direct-administered municipalities in China. The questionnaires were collected and a special Excel database was set up for statistical analysis using SPSS 22.0. Results A total of 126 practitioners responded and completed the questionnaire. Approximately 75.4% of respondents indicated that they either “understood” or “understood well” the standard; 42.86% received relevant training; 45.24% and 54.76% indicated that the standard “met” or “basically met” the requirements of detection of γ-ray radiotherapy equipment shielding or design of shielding room. The standard was highly evaluated for suitability. However, the awareness of the standard was inadequate, the rate of training participation was low, and its practical application was limited. Conclusion The standard generally aligns with the requirements for shielding room design in γ-ray radiotherapy. Some revisions should be done according to the current situation of γ-ray radiotherapy.
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Objective To investigate the awareness of the Radiation Shielding Requirements for Radiotherapy Room–Part 2: Radiotherapy Room of Electron Linear Accelerators (GBZ/T 201.2—2011) among relevant practitioners in medical institutions as well as its implementation and application situation and collect relevant problems and suggestions for an evaluation of the scientificalness, standardization, and timeliness of the standard, and to provide a scientific basis for the further revision and implementation of the standard. Methods An online questionnaire survey was conducted among relevant employees in medical institutions providing medical linear accelerator radiotherapy across 22 provinces of China, which investigated the awareness, training, application, and revision suggestions related to GBZ/T 201.2—2011. The questionnaires were collected and analyzed. Results A total of 340 relevant practitioners filled out the questionnaire. Of the participants, 66.80% were physicists; 79.11% had an awareness of the standard; 56.18% ever participated in the standard-related training; but the survey results showed that the practitioners did not have a good knowledge of the standard’s content, and the training and promotion were not enough; 83.24% thought that the standard had been widely used; 17.60% thought that the standard needed to be revised; 76.76% thought that there was a need to add calculation examples; 88.82% thought that neutron shielding needed to be considered for the 10 MV X-ray accelerator room. Conclusion The standard has been widely known in the field of radiotherapy protection. With the development of radiotherapy technology, the standard should be revised to add calculation examples and consider neutron shielding in the 10 MV X-ray accelerator room. The standard is highly technical and difficult to grasp, so the promotion and implementation goals should be appropriate for different personnel groups, the training for employees at key posts should be strengthened, and the methods recommended in the standard should be uniformly used throughout the country.
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Objective @#To evaluate the implementation, application, and problems and suggestions of the Radiation Shield- ing Requirements in Room of Radiotherapy Installations—Part 1: General Principle (GBZ/T 201.1—2007) through a survey of relevant personnel in radiation health technical service institutions, and to provide a scientific basis for further revision and implementation of this standard.@*Methods@#A questionnaire survey was conducted among randomly selected per- sonnel in radiation health technical services across China, which mainly investigated the awareness, training, application, and revision suggestions related to the GBZ/T 201.1—2007. The results were aggregated and analyzed.@*Results@#A total of 184 evaluation questionnaires on the GBZ/T 201.1—2007 were collected from technical service staff in 25 provinces. Among the responders, 64.1% thought that the standard had been widely applied; 91.8% thought that the standard could meet work needs; only 54.3% ever received relevant training on the standard; 68.5% used the standard once or more per year; 33.7% thought that the standard needed to be revised.@*Conclusion@#The personnel in radiation health technical services have a high awareness rate of the GBZ/T 201.1—2007 and its contents, but their familiarity with and application of the standard need to be improved. Relevant departments should strengthen the training and promotion of the standard, and part of the standard should be revised.
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Objective To determine the current status of occupational internal exposure to 131I in the thyroid of nuclear medicine workers, to explore the influencing factors for internal exposure, and to provide a basis for the radiation safety management of nuclear medicine. Methods The cluster sampling method was used to select 162 workers practicing 131I treatment in 24 hospitals in Hubei Province, China. Thyroid 131I activity levels were measured in vitro using a portable γ-spectrometer, and the committed effective dose was estimated. Results The thyroid 131I activity detected in 13 (54.17%) hospitals was above the lower limit of detection of the instrument. Two hospitals had the highest detection rates, 62.50% and 61.90%; the difference was significant compared with the remaining 11 hospitals (P < 0.0001). Thyroid 131I was detected in 34 workers in total, with a detection rate of 20.99% and a mean activity of 179.09 ± 138.71 (6.02-589.74) Bq. The highest detection rates were found in cleaners and nurses, which were 35.71% and 33.33%, respectively, with no significant difference in detection rate between positions (least P > 0.08). The mean value of the committed effective dose was 0.68 ± 0.52 (0.02-2.22) mSv/a in the 34 workers. Conclusion The 131I consumption and workplace ventilation may be important factors affecting the level of internal exposure. It is important to strengthen the training of nuclear medicine workers on radioprotection and workflow management, as well as the regular monitoring of occupational internal exposure for 131I treatment-related workers.
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@#<b>Objective</b> To analyze the process of intercomparison of national personal dose monitoring, evaluate the ability of personal dose monitoring, and ensure the accuracy and reliability of monitoring results in our laboratory. <b>Methods</b> In accordance with the intercomparison protocol for 2019—2021, an energy-discriminant thermoluminescence dosimeter was used for measurement at different doses. The uncertainty of measurement was evaluated and compared with the reference value. <b>Results</b> <i>H</i><sub>p</sub>(10) was measured for intercomparison in 2019—2021. In 2019, the single group performance difference was −0.02 to 0.02 and the comprehensive performance was 0.02. These values were 0.02-0.10 and 0.05 in 2020, and −0.02 to 0.02 and 0.01 in 2021. The intercomparison results were rated as excellent in the three consecutive years. <b>Conclusion</b> The personal dose monitoring system in our laboratory was in good condition, and the monitoring results were accurate and reliable. Improving the knowledge of personnel and cultivating a serious working attitude are important for intercomparison and personal dose monitoring.
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Objective To explore the absorbed dose to the common tissues of subjects in four clinical CT scanning modes and the spatial distribution of the radiation field in chest scanning, in order to provide a basis for the radiation protection of subjects and the space in the machine room. Methods A thermoluminescence detector (TLD) was used to measure the absorbed doses to the eye lens, thyroid gland, gonad, chest and abdominal skins of the anthropomorphic phantom in four CT scanning modes. The TLD was used to monitor the air kerma at different positions from the CT diagnostic table during chest spiral scanning. Results The absorbed doses to the eye lens, thyroid gland, gonad, chest and abdominal skins of the anthropomorphic phantom in four CT scanning modes were 0.040-64.818 mGy, 0.154-10.155 mGy, 0.028-0.154 mGy, 0.443-17.141 mGy, and 0.093-14.346 mGy, respectively. The maximum air kerma value of the space radiation field during chest scanning was 0.049 mGy, and the farther the distance from the CT tube, the smaller the value. Conclusion The absorbed doses to the common tissues of subjects examined by the four CT scanning modes generally do not exceed the threshold doses. The dose received by the companion of the subject during a single chest CT scan was small. In order to minimize radiation hazards, shielding measures can be taken in CT scanning to reduce the absorbed doses to the tissues of the subject, and the companion of the subject should appropriately increase the distance from the tube and the diagnostic table.
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@#<b>Objective</b> To explore the quality control results of Digital Diagnost digital radiography (DR), and also to analyze the differences in signal transfer characteristics (STP) of DR from different manufacturers, in order to provide a reference for quality control of testers and daily supervision of administrative staff. <b>Methods</b> According to WS 76—2020 “Specification for testing of quality control in medical X-ray diagnostic equipment”, the test items such as automatic exposure control (AEC) repeatability, AEC response, detector dose indication (DDI), STP, high-contrast resolution, and low-contrast resolution of Digital Diagnost DR were qualitatively controlled, and several common DRs on the market were selected to analyze their STP functional relationships. <b>Results</b> The baseline values of DDI, high-contrast resolution, and low-contrast resolution of Digital Diagnost DR were 19733, 2.8 Lp/mm, and H5 of image central pixel value, respectively; the quality control results of other test items met the requirements of WS 76—2020. The STP functional relationships of common DRs were mainly linear and logarithmic, but different models of DR from the same manufacturer might also have different STP functional relationships. <b>Conclusion</b> When testing some special test items of DR, attention should be paid to the influence of a variety of factors, while refining the test steps and condition settings for the test items. The simulation should be performed in accordance with the functional relationship provided by the manufacturer when analyzing the STP.
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210Po and 210Pb exist widely in nature, and they have strong toxicity and strong ionization ability, which can cause continuous harm to human health. Therefore, it is of great significance to determine the activity concentrations of 210Po and 210Pb in environmental samples and to evaluate their harmful effects on human health. This article reviews the research progress in analytical methods and measurement techniques of 210Po and 210Pb in environmental samples.
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Objective To analyze the status quo and existing problems of radiation protection for veterinary X-ray facilitiesin Beijing-Tianjin region, China, and to provide a basis for improving radiation protection management level. Methods According to the requirements of the Technical guidelines for status quo assessment of occupational hazard of the employing unit (AQ/T 4270—2015), the study performed status quo assessment on the workplaces of veterinary X-ray facilities in 16 pet hospitals in Beijing-Tianjin region, and comprehensively analyzed the impact of the workplaces on the health of radiation workers and the public. Results In terms of personnel management, the pass rates of occupational health management post setting, personnel training, personal protective equipment, individual monitoring of occupational external exposure, notification of occupational hazards, and occupational health surveillance were 100%, 81.3%, 100%, 75%, 37.5%, and 25%, respectively. In terms of workplace management, most workplaces had reasonable layout and zoning and complete protection and emergency devices. However, there were some problems in some places, such as non-standard radiation warning signs, no notice board of occupational hazards, and no radiation protection testing. In terms of document management, all institutions had imperfect system documents. Conclusion The workplaces of veterinary X-ray facilities in 16 institutions basically meet the requirements for radiation protection, but there are also some problems, such as inadequate management of personnel and workplace radiation protection, and imperfect system documents. Institutions should strengthen the study of radiation protection knowledge. The competent authorities should strengthen supervision, formulate corresponding standards for radiation protection, enhance training, and improve the professional level of staff.
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Objective:To discuss the problems existing in the implementation of the Chinese health industry standard WS 523-2019 by testing SPECT device.Methods:Under the WS 523-2019 standards, a total of 10 SPECT devices were tested with regard to their SPECT reconstructed spatial resolution (SRSR), system planar sensitivity (SPS), system spatial resolution (SSR), whole body system spatial resolution (WSSR), intrinsic uniformity (IU), intrinsic count rate performance (ICR), intrinsic spatial resolution (ISR) and intrinsic spatial linearity(ISL).Result:Under the requirements of WS 523-2019 standards for qualified limits, there are 3 devices with ISL unqualified and the rest of the performances qualified. The new standards basically can meet the clinical requirements and reflected the overall performance of SPECT.Conclusions:The distance between the radiation source and the surface of the detector has great influence on the spatial resolution.In the measurement of ISL, there must be a lead grid separately in the x and y directions. The lead grids with the parallel slits shall be positioned on the detector with the center slit centered on the detector. It is suggested to add rotation center in the new standards.
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Objective To measure the peripheral dose distributions of the mobile head cone beam computed tomography (CBCT) and evaluate the impact of CBCT on the surrounding personnel and environment, and provide data support for clinical radiation protection management. Methods Combined with the structural characteristics of CBCT, AT1123 was used in the direction of 0° (counterclockwise), 45°, 90°, 135°, 180°, 225°, 270° and 315° in front of CBCT to measure the ambient dose equivalent rate of 30 cm, 80 cm and 130 cm away from the ground when the equipment was normally out of the beam, and the boundary of the temporary control area was drawn. At the same time, the dose level behind the lead screen 1 m away from the external surface of the equipment was measured and analyzed. Results The dose field around CBCT was symmetrically distributed with the dividing line of 0° and 180°, and the radiation dose level of 5.5 m in the direction of 0°, 3.5 m in the direction of 45°, 0.5 m in the direction of 90° and within 1.0 m in the direction of 180° (inside the "spoon" type) was higher than 2.5 μSv/h. The radiation dose levels of CT aperture 0° (straight forward), 45° and 315° behind the lead screen 1 m away from the equipment surface were 0.37 μSv/h, 0.22 μSv/h and 0.54 μSv/h, respectively. Conclusion The results show that the radiation dose around the mobile head cone beam CT is in a low dose level, the distribution of the dose field can provide necessary reference for the administrative and medical personnel to strengthen the radiation safety management. At the same time, it is suggested that lead screens should be set up in the clinical use of mobile CT to ensure the health and safety of the surrounding people and the environment.
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Objective To evaluate the current status of radioactive occupational hazards in the construction of some medical institutions in Tianjin, discover existingproblems and deficiencies, and provide a technical basis for radiation protection management. Methods Based on the requirements of relevant regulations and standards, we comprehensivelyevaluated the results of the pre-evaluation and control effect evaluation of 81 radioactive occupational hazards in Tianjin. Results Among the 35 proposed protective measures for pre-evaluation of radiation occupational hazards constructionprojects, the lowest compliance rate is warning signs and personal protective equipment. Among the 46 construction projects of radioactive occupational hazard control evaluation, the pass rate of protective measures was between 73.9% and 100%, with the lowest pass rate for personal protective equipment. Besides, the pass rate of radiation protectionmanagement evaluation was 95.7% ～ 100%, with the lowest pass rate for the protection management system.The initial inspectionpass rateof the equipment quality control acceptancewas 98.6%, while the pass rate was 97.1% for the relevant workplace radiation protection during the initial inspection. Conclusion The pre-evaluation completion rate of radiological occupational hazard evaluation in Tianjin medical institution construction project, unilateral and area of construction room, workplace layout and zoning, ventilation, shielding measures, personal dose management and occupational health inspection all meet the requirements of regulations and standards. However, there are still some deficiencies in the personal protective equipment, warning signs and the radiation protection management system. Therefore, the regulatory department should further strengthen the evaluation of medical institutions, especially the key supervision and management of non-conformities.
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Objective The purpose of this study is to grasp the current situation of radiation protection in some non-medical institutions in Hangzhou, and to provide basis and reference for the relevant authorities departments to make the radioactive hazard factors monitoring plan for non-medical institutions. Methods The configuration of the personnel protective equipment and radiation level of radiation sources and radiation devices in 5 non-medical monitoring institutions in Hangzhou were investigated and analyzed by means of questionnaire survey and on-site detection. Results The radiation workers of 5 monitoring institutions have carried out personal dose monitoring, and their annual individual dose equivalent meets the requirements of relevant national standards. The ambient dose equivalent rates around the radiation source and radiation device room are lower than the minimum detection limit of the instrument. When the source is stored, the maximum ambient dose equivalent rates at 5 cm and 100 cm away from the external surface of the source container were 22.2 μSv/h and 2.0 μSv/h, respectively. When the source is in use, the maximum ambient dose equivalent rates at 5 cm and 100 cm away from the external surface of the source container were 44.3 μSv/h and 5.0 μSv/h, respectively. Conclusion Under normal operation, the radiation dose level of some non-medical monitoring institutions in Hangzhou is at a low level, while the ambient dose equivalent rates around the external surface of the source container is at a high level. Therefore, non-medical institutions should improve their awareness of radiation protection and strengthen radiation management.
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Objective:To study the dose response of two-dimensional ionization chamber matrix detectors under IMRT fields irradiation at different gantry angles and different directions.Methods:After the dose calibration of the medical accelerator and the two-dimensional ionization chamber matrix detector respectively, the solid water phantom was used to cover the upper part of the two-dimensional ionization chamber matrix detector. Adjusting the thickness of the solid water, the effective distances between the effective measuring center of the two-dimensional ionization chamber matrix detector and the incident point of the central axis of the radiation on the surface of the phantom was always controlled at 5 cm. Four locations with 0、45、90 and 135 degrees of the long axis of the treatment bed were selected, and each location was irradiated by IMRT fields at different frame angle of 60°, 45°, 30°, 15°, 0°, -15°, -30°, -45° and -60°, respectively.Results:The dose deviation of the medical accelerator was less than 0.18% in the range of different rack angles. The directional response deviation of the two-dimensional ionization chamber matrix detector was less than 0.63%, and the measurement deviation of each probe of the two-dimensional ionization chamber matrix detector to its center probe was less than 0.50%.Conclusions:The two-dimensional ionization chamber matrix detector has good directional response and it is a useful tool for developing intensity-modulated radiotherapy technology. The method proposed in this study can provide a basic basis for the relevant medical accelerator metrology departments to formulate corresponding quality control test specifications.
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Objective To evaluate the radiation protection of occupational hazards in a hospital Clinac 23EX medical electronic accelerator construction project so as to ensure the health and safety of the relevant people involved.Methods According to the relevant laws,regulations and standards of China,combined with the relevant materials provided by the construction unit,the radiation protection tests and comprehensive assessment of this project were carried out.Results The performance test results of the medical electron accelerator met the requinements of GB/T 19046-2013 The ambient dose equivalent rate in the workplace was between the background dose rate (0.10 μ,Sv/h) and 11.5 μSv/h,which suggested the computer room shielding met the requirements of radiation protection.The total body effective dose,the for 7 radiation workers were 0.85,1.19,1.64 mSv,respectively,which were lower than the dose management control values of the construction unit and the national standards.Radiation protection supplies and the management system of the construction unit met the national requirements.Conclusions The construction project can effectively control the radioactive occupational hazard factors in normal operation,and the radiation protection facilities have reached the completion requirements.
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Objective To investigate the effect of SKP2 expression on radiation induced bystander effect (RIBE) of esophageal cancer cells.Methods The esophageal cancer cell lines with different SKP2 levels were applied for the study and the SKP2 expression was identified by Western blot.Micronuclei (MN) assay and DNA foci assay were used to evaluate the effect of SKP2 on RIBE.The cells were transfected with SKP2 gene or SKP2 siRNA to further verify the effect of SKP2 on RIBE.Results MN assay showed that the bystander effect induced by the cells with a high level of SKP2 was lower than that induced by the cells with a lower level of SKP2 (t =8.06,P ＜ 0.01).These results were further confirmed by the gene transfection experiments.When the expression of SKP2 was increased,RIBE was decreased (t=11.12,10.16,P ＜ 0.01).Contrarily,when the expression of SKP2 was reduced,RIBE was increased (t =8.39,8.83,P ＜ 0.01).γ-H2AX foci formation assay disclosed that when SKP2 expression in the irradiated cells increased,the repair ability of DNA damage in the bystander cells was higher than the control (t =6.85,7.10,P ＜ 0.01).With the expression of SKP2 decreased,the repair ability of DNA damage was lower than the control (t =7.66,8.47,P ＜ 0.01).Conclusions Over-expression of SKP2 inhibits RIBE of esophageal cancer cells,at least partly through regulating DNA damage repair ability.
