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Objective: To investigate the implementation of GBZ/T 201.3-2014 Radiation Shielding Specification for Radiotherapy Room--Part 3: Radiotherapy Room of γ-ray Sources (hereinafter referred to GBZ/T 201.3-2014). Methods: A total of 129 personnels, who were involved in the approval and supervision of radiation diagnosis and treatment construction projects in 19 provincial administrative agencies, engaged in radiation protection testing and evaluation of γ-ray radiotherapy rooms in radiation health technology service institutions, and used GBZ/T 201.3-2014 in other institutions (environmental impact assessment, education and scientific research), were selected as the participants using a stratified random sampling method. A questionnaire survey was conducted to assess their awareness and application of the standard. Results: The participants' awareness of GBZ/T 201.3-2014 was ≥63.6%, but the training rate was only 9.1% to 50.0%. The familiarity with the various chapters of the standard was over 86.4%. And 42.6% of the participants reported using the standard at least once a year. Regarding the applicability of the standard, all of the participants believed that the standard meets the needs of approval, supervision, testing, or evaluation, and adapts to the updated development of radiotherapy equipment and technology. And 94.6% of the participants believed that the use of the standard could improve the level of protection design and management, and 92.2% believed that the standard was widely applied. Regarding the adequacy of the standard, 97.7% of the participants believed that the standard's reference for ambient dose equivalent rate was reasonable, while 34.1% believed that the standard needs revision. Conclusion: The participants are satisfied with the standard and believe its applicability. They have a good level of awareness of the standard, but there is a room for improvement in their familiarity with the shielding calculation related content of the standard. The promotion, training, and practicality of the standard need to be strengthened.
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Objective To evaluate the radiation protection of “four-in-one” dental X-ray equipment and to investigate the safety interlock of the equipment by measuring the scattered radiation at the position of the patient during operation. Methods A cone-beam CT dental phantom was used to simulate the patient’s head. The intra-oral and extra-oral components of the “four-in-one” X-ray equipment were installed in a 5 m2 room. The scattered radiation at patient position was measured using a γ/X-ray survey meter, and the effects of intra-oral and extra-oral components were compared. Results For a 5 m2 room, when CBCT was exposed under typical conditions, the dose at the patient's position was 10.70 uSv/h when there was an intra-oral component and 10.60 uSv/h when there was no intraoral component. The intra-oral part did not affect the radiation dose at the patient's position. When the intra-oral component was exposed, the dose rate at the patient's position was 4.05-6.85 uSv/h, and the extra-oral part did not affect the scattered dose of the patient examined with intra-oral components. Conclusion The evaluation of radiation protection of new equipment must comprehensively consider radiation safety and equipment operation safety. The results of this study provide suggestions for clinical radiation protection supervision and evaluation of “four-in-one” dental X-ray equipment.
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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 explore the present state of radiation protection in an operational large-sized irradiation facility and the distribution of incurred radiation doses in the controlled area under abnormal conditions, and to analyze the acompanied radiation risk.Methods:With an irradiation facility in operation as the research object, the radiation doses were measured using AT1121 X and gamma dose rate meters for the soruce both in working and storage. Thermoluminescent dosimeters (TLDs) were used to measure the dose distribution in an irradiation field under abnormal conditions. The radiation safety features were checked against the several relevant national standards, with the radiation risks evaluated.Results:The radiation dose rates were in the range of 0.09-0.11 μSv/h, lower than the environmental background level whether in storage or working. Under abnormal working conditions, the radiation dose values from high to low were 1.0-101.3 Sv, 32.7-514.0 mSv and 8.7-183.2 μSv in the irradiation field, respectively. At the outside maze, the doses were close to the background level.Conclusions:The protection features of the irradiation facility meet the requirements of the relevant national standards. Under abnormal conditions, radiation could cause serious damages to the persons staying in the irradiation field. These persons were suggested to access to maze as soon as possible to reduce the exposure time, and activate the emergency protection equipments to deescalate the 60Co source onto the well.
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Objective:To describe the distribution of volumetric breast density(VBD) in different ages of Chinese women based on X-ray mammograms.Methods:Based on mammographic images of 1 140 patients from January 2010 to December 2016 in a hospital in Beijing, the VBD of women was assessed by Volpara 1.5.1 and graded according to breast imaging reporting and data system published by American College of Radiology. The patients were divided into two groups according to the median age, and the two independent samples t-test was used to compare them. The patients were also divided into four groups according to age ( <40 years, 40-49 years, 50-59 years, ≥ 60 years), and the breast thickness, breast volume, glandular volume, and VBD were compared using a One-way ANOVA analysis. Results:The median age was 50 years. The compressed breast thickness and breast volume in patients over 50 years were significantly higher than those in patients below 50 years ( t= -8.99, -7.92, P<0.001), while glandular volume and VBD were significantly lower than those below 50 years ( t= 8.11, 18.49, P<0.001). The compressed breast thickness, breast volume, glandular volume, and VBD were statistically significant different among four groups ( F=27.10, 22.34, 25.70, 122.03, P<0.001). Patients over 60 years had the lowest VBD ( t=-12.56, -15.27, -4.57, P<0.001). VBD was negatively correlated with ages ( r=0.47, P<0.001). Conclusions:The compressed breast thickness and breast volume increased with ages, while the glandular volume and VBD decreased with ages.
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Objective:To monitor and analyze the activity concentrations of 7Be and 210Pb in atmospheric aerosol in Beijing from 2017 to 2020. Methods:Totally 1 074 atmospheric aerosol samples were collected by high flow air sampler (SnowWhite) including 275 in spring, 266 in summer, 262 in autumn and 271 in winter and subjected to analysis by low background high-purity germanium gamma-ray spectrometery (ORTEC) to determine the activity concentrations of 7Be and 210Pb. Results:The activity concentrations of 7Be in atmospheric aerosol were from 0.56 to 14.84 mBq/m 3, with an avearage of 6.84 mBq/m 3, and from 0.01 to 9.37 mBq/m 3 for 210Pb, with an avearage 3.19 mBq/m 3. The differences in activity concentrations of 7Be and 210Pb in atmospheric aerosol among differernt seasons were statistically significant ( F=32.66, 93.93, P<0.05). Activity concentration of 7Be was highest in spring, followed by autumn, and lowest in summer and winter. Activity concentration of 210Pb ranged from winter, autumn, spring to summer in descending order. Conclusions:The activity concentrations of 7Be and 210Pb in atmospheric aerosol in Beijing from 2017 to 2020 fluctated within the range of normal level.
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Objective:To compare the calculation result and analyzes the reasons for their differences so as to provide reference for the revision and improvement of the current national standards on radiation shielding design for the room of brachytherapy.Methods:For the initial activity 10 Ci (1 Ci=3.7×10 10 Bq) of radioactive sources, the shielding schemes of brachytherapy room were designed in accordance with UK Institnte of Physics and Engineering in Medicine(IPEM) Report 75, USA NCRP Report 151 and the national standard GBZ/T 201.3-2014, respectively. The differences in shielding limits, occupancy factors and other relevant factors are compared in detail. Results:The annual exposure time in a typical brachytherpy room was about 330 h. The point-specific concrete thickness were 70, 65, 61, 70, 50 cm as required by NCRP Report 151, 41, 43, 30, 40, 39 cm by IREM regulations and 84, 79, 46, 88, 39 cm by GBZ/T 201.3, respectively. The concerned concrete shielding thickness calculated under the GBZ/T 201.3-2014 was generally thicker, with lesser difference from NCRP Report 151 result, whereas that from the IPEM75 report was thinnest. The equivalent lead shielding thicknesses of the protective doors calculated using the three method are 1.170, 0.854 and 1.040 cm, respectively.Conclusions:The shielding thickness calculated using the calculation method and evaluation index recommended by the current Chinese shielding standards for brachytherapy bunker is similar to that reported in NCRP151, but is conservative. In particular, the evaluation index of instantaneous dose equivalent rate required by the current national standards and the relative conservative value of occupancy factor will significantly increase the shielding thickness required by the main shielding area.
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Objective To analyze the distribution status and agglomeration degree of radiological diagnosis and treatment resources in Beijing, and provide references for rationally coordinating the allocation of radiological diagnosis and treatment resources, formulating resource allocation policies, and promoting the stable development and efficient use of radiological diagnosis and treatment resources. Methods Based on the medical radiation protection monitoring data of Beijing medical and health institutions from 2019 to 2020, the current situation of radiological diagnosis and treatment resources is described by the number of radiological diagnosis and treatment resources, the average service volume, and the resource composition, and the distribution of radiological diagnosis and treatment resources in Beijing is evaluated with the aid of the agglomeration degree. Results The number of radiological diagnostic equipment, the number of service personnel, and the number of radiological workers engaged in third-level hospitals is the largest; for the number of service personnel for each type of single equipment, third-level hospitals account for a larger proportion, and radiotherapy and nuclear medicine services are concentrated in third-level hospitals. Human resource pressure and equipment service pressure are relatively high in third-level hospitals. First-level hospitals mainly undertake radiological diagnosis services. There is little difference in the amount of radiological diagnosis services per capita between second-level hospitals and third-level hospitals. Nuclear medicine and radiotherapy in third-level hospitals per capita service volume is significantly higher than that insecond-level hospitals. Radiological diagnosis and radiotherapy resources are concentrated in urban areas to a large extent. Conclusion There are obvious differences in the utilization of radiological diagnosis and treatment resources in different levels of hospitals. There is a significant concentration of radiological diagnosis and treatment resources in various districts. There is a certain degree of unbalanced distribution and inadequate utilization of radiological diagnosis and treatment resources in Beijing.
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Objective@#To study the output dose of external beam radiotherapy in Beijing and analyze the cause of output dose deviation. Guidance is given on the selection of measurement methods, calculation formulas and parameters.@*Methods@#During 2020, the output doses of medical electron accelerators, tomotherapy, cyberknife, and γ-knife were meas- ured based on the water absorbed dose calibration factor combined with the requirements in the IAEA TRS398 and TRS483 reports, and low-energy X-rays were measured based on the air kerma calibration factor combined with the requirements in the AAPM protocal. The output dose was measured and compared with the preset irradiation value.@*Results @#A total of 59 external beam radiation therapy equipments’s output dose were investigated.2 of the 49 accelerators’s absolute value of relative deviation between the system indication value and the measurement exceeded 3%; the deviation of other external beam radiotherapy equipments was less than 3%.@*Conclusion @#A unified method and multi-party quality control can ensure the accuracy of the output dose. In the routine operation of the equipment, the hospital should strictly implement periodic inspections to ensure accurate and reliable radiotherapy.
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Objective@#To analyze the absorptive radiation dose of non-target sensitive organs under the NewTomVGi oral and maxillofacial cone-beam CT scanning in different view fields.@*Methods@#The thermoluminescence dosimeter chip was placed in the non-target sensitive organ of the simulated radiology head model, and 6 scanning fields were measured and analyzed (standard resolution: scanning range was 15 cm×15 cm, 15 cm×12 cm, 12 cm×8 cm, 8 cm×8 cm respectively). High definition resolution: the radiation absorption dose of thermoluminescence with the scanning range of 12 cm×8 cm, 8 cm×8 cm, respectively.@*Results@#Under the same resolution, the absorptive dose increased with the expansion of scanning field, and the amount of absorbent during high resolution scanning was higher than that during the standard resolution with the same scanning field.@*Conclusions@#New TomVGi oral and maxillofacial cone-beam CT has sighificant difference in radiation dose in different view fields. The appropriate view field should be selected according to the patient′s clinical needs, so as to reduce unnecessary radiation dose during medical imaging examination.
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Objective To analyze the performance differences of CT scanners with different detector rows between different manufacturers,and to provide the basis for the rational allocation and use of these CT scanners.Methods According to the result from the sentinel surveillance in 2014,a total of 148 medical institutions were equipped with CT scanners in 16 districts of Beijing,including general hospital(53),cancer hospital(5),TCM hospitals(25),children′s hospitals(2),community hospitals(30)and other specialized medical institutions(33).According to the principle of simple random sampling,40 medical institutions are selected,including 14 general hospitals,1 cancer hospital,7 Chinese medicine hospitals,1 children′s hospital,8 community hospitals and 9 other specialized medical institutions.A total of 141 CT scanners are selected from all CT sets of the selected medical institutions from 2012 to 2014.According to GB 17589-2011 X-ray computed tomography device quality assurance testing status test,four parameters related closely to image quality were tested,including CT value(water),noise,high contrast resolution,and low contrast detectability.Results No significant differences were found in CT value(water),noise and low contrast detectability among CT scanners produced by different manufacturers(P＞0.05),whereas high contrast resolution was found to have a remarkable difference(χ2＝34.706,P＜0.05).Significant differences were found in noise,high contrast resolution and low resolution detectability between the CT scanners with ＜64 detector rows and ≥64 detector rows(χ2＝6.978,10.040,15.973,P＜0.05).However,there is no difference in CT value(water)(P＞0.05).For less-than-64 detector row CT scanners,no significant difference was found in CT value(water),noise and low contrast detectability among different manufacturers(P＞0.05).only high contrast resolution differed remarkably(χ2＝9.941,P＜0.05).For more-than-or equal-to-64 detector row CT scanners,CT value(water)and noise have no differences among different manufacturers(P ＞0.05),whereas,there were significant difference in high contrast resolution and low contrast detectability(χ2＝31.376,32.967,P＜0.05).Conclusions There were a few differences in the performance testing of CT scanners from different manufacturers,and the less-than-64 detector row CT scanners have advantages in noise and low contrast detectability compared with the more-than-64 detector row CT scanners,whereas the latter have advantages in high contrast resolution and scanning time,allowing its wider application in medical institutions with more special diseases.
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Objective To understand the functional status and radiation protection requirements of helical tomotherapy (TOMO) unit when it is applied in clinic treatment so as to promote the construction of TOMO quality control system.Methods A helical tomotherapy unit with a type of tomotherapy Hi-Art was employed as the radiotherapy unit.A series of tests and analyses on dosimetric and radiation safety performance parameters of the TOMO unit were conducted with the use of a A1SL ionization chamber,a set of solid water equivalent phantoms and other test equipments.The performance parameters were compared with that of a conventional 6 MV accelerator with a type of ARTISTE.Results The deviations of static and dynamic output dose were-1.51％ and 1.18％,respectively.The values of PDD10/PDD1.5 and PDD20/PDD1.5 were 0.608 and 0.318 within the range of X-ray quality parameters calibration.Under the different field conditions of 40 cm × 5 cm,40 cm × 2.5 cm and 40 cm × 1 cm,the stability of transverse/longitudinal dose distribution curve was no more than 1.20％ and the offset distance of Jaw width was smaller than 0.5 mm.Radiation leakage ratio of the treatment rotating center from the muhileaf collimator (MLC) was 0.20％.No matter the average or the maximum value of the leakage radiation from couch plane was less than 0.02％.Conclusions The performances and testing requirements of TOMO unit are different from a conventional electron linear accelerator,the quality control index of TOMO unit should be set seperately and tested strictly in terms of the specific requirements of the unit by complying with the QC programme.The reliable quality control system should be established and effectively implemented to serve the radiotherapy quality and radiation safety effectively in the tomotherapy.
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Objective To investigate the radiation dose levels to the adults examined from diagnostic exposure in Beijing. Methods The radiation doses to the examined individuals were measured by using individual diagnostic radiology equipments in 30 random hospitals from a total of 10 districts and suburban areas, including 1 182 samples of X-ray photography,542 samples of mammography and 410 samples of CT examination. Results 2 134 samples were measured in this study. The dose ranges of X-ray photography, CR, and DR were 0?4 -24?1, 0?3 -13?9 and 0?1 -15?9 mGy, respectively. The average dose range of glandular breast was 0?3-5?4 mGy. In 410 CT samples the value of CTDIw , CTDIvol and DLP were 28?1 - 96?3 mGy, 7?0 - 23?4 mGy, and 162?2 - 898?1 mGy·cm, respectively. Conclusions Several dose levels from diagnostic examination were higher than guidance level for medical exposure in GB 18871-2002,which should be noted.
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Objective To study the radiation dose level and dose distribution of leakage and scattering radiation in a helical tomotherapy (TOMO) room,and to identify the dose distribution characteristic which is different from the conventional radiotherapy so as to provide scientific data for the radiation protection of TOMO.Methods A helical tomotherapy facility typed Tomotherapy Hi-Art was employed as the radiotherapy device.The air kerma from leakage radiation and scattering radiation distributed on the couch plane and in TOMO room were detected mainly by GR-200A TLDs of LiF(Mg,Cu,P),while 100 Gy were being accumulated under the condition of simulation radiation treatment.Then,the leakage radiation ratio and scattering-leakage radiation ratio (the ratio of site radiation dose to isocenter standard output dose) were calculated.Results The radiation level and dose distribution of leakage radiation and scattering radiation in the TOMO treatment room were in bilateral symmetry to the rotation isocenter and the treatment couch longitudinal axis,and the radiation level in front of the radiotherapy device was significantly higher than that of the rear of the TOMO equipment.In the plane of treatment couch,the maximum leakage radiation ratio at the position 100 cm away from the isocenter was only 1.3 × 10-4,and the mean value of the leakage radiation ratio at the position 300 cm away from the isocenter was lower than 2.0 × 10-5.The scattering radiation at 200-300 cm away from the isocenter was accounted for 25％-30％ of the leakage radiation from the responding sites,and the indoor scattering radiation decreased faster than leakage radiation with the distance from the isocenter.Conclusions The radiation level of leakage and scattering in a TOMO room is significantly lower than that in a conventional radiotherapy room.
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Objective To assess the level of radiation exposures of operators in three typical types of interventional fluoroscopic procedures.Methods Alderson Radiation Therapy (ART) phantom was used to stimulate the practices of diagnosis and therapy using TLDs for dose measurement.The radiation exposures of eye lens, neck, and breast were measured when the lead shielding of machine was on/off and the equivalent dose and effective dose to the eye lens were estimated.Results Radiation exposure of head was obviously reduced by 85% -90% when the lead shielding was on.The doses in different procedures were different.In cerebral angiography the dose equivalent of eye len was the highest in the three procedures.The annual effective dose for the operators was smaller in peripheral vascular interventions than that in cardiovascular interventional therapy and that in cerebral angiography.Conclusions The operators involved in intervention will receive an annual effective dose of less than 20 mSv as recommended by the ICRP under the protection conditions provided by the current study, except for eye lens.Attention should be paid to the protection of the eyes of operators.