Comparison of Chinese and international radiation shielding standards in application for after loading bunker shielding design
10.3760/cma.j.issn.0254-5098.2021.07.010
- VernacularTitle:中外近距离治疗机房辐射屏蔽设计标准应用比对
- Author:
Lang YU
1
;
Bo YANG
;
Xiansong SUN
;
Zechen FENG
;
Jie QIU
Author Information
1. 北京市放射治疗质量控制中心 中国医学科学院北京协和医院放疗科 100730
- Keywords:
Afterloader;
192Ir source;
Shielding Design;
Instantaneous dose-equivalent rate;
Standard
- From:
Chinese Journal of Radiological Medicine and Protection
2021;41(7):529-533
- CountryChina
- Language:Chinese
-
Abstract:
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.
