18MV加速器调试机房防护门的屏蔽效果及其影响因素分析  

Analysis of the shielding effect of protective door of an 18 MV linear accelerator debugging room and its influencing factors

作　　者：张国海 章斌 张贵英 马永忠[3] ZHANG Guohai;ZHANG Bin;ZHANG Guiying;MA Yongzhong(Varian Medical Systems Trading(Beijing)Co.,Ltd.,Beijing 100176 China;Beijing Prevention and Treatment Hospital of Occupational Disease for Chemical Industry,Beijing 100093 China;Beijing Center for Disease Control and Prevention,Beijing 100013 China)

机构地区：[1]瓦里安医疗器械贸易(北京)有限公司,北京100176 [2]北京市化工职业病防治院,北京100093 [3]北京市疾病预防控制中心,北京100013

出　　处：《中国辐射卫生》2024年第3期254-259,共6页Chinese Journal of Radiological Health

摘　　要：目的研究无迷路医用直线加速器生产调试机房防护门屏蔽效果及其影响因素,为生产调试人员放射性职业病危害防护提供指导。方法以某18 MV医用直线加速器及其新建无迷路调试机房防护门为研究对象,防护门屏蔽材料由内往外的排列结构为2.5 cm钢板+20 cm铅+41 cm含5%硼聚乙烯+6 cm铅+2.5 cm钢板,防护门右侧设置有凹槽(俗称“门口袋”)搭接,分别在不同搭接宽度、不同照射方向和加速器机座不同安装位置的条件下,使用FLUKE451P和WENDI II中子巡检仪测试防护门外关注点的周围剂量当量率,分析其屏蔽效果及影响因素。结果当防护门两侧搭接宽度为300 mm时,有“门口袋”一侧的防护门前周围剂量当量率为(1.37±0.05)μSv/h,无“门口袋”一侧为(4.71±0.11)μSv/h和(4.19±0.11)μSv/h;在加速器主束朝东照射时,防护门外关注点的周围剂量当量率均高于其他主束照射方向时门外相应关注点的剂量率;当加速器机座位于机房南侧时,相同照射条件下防护门外关注点的周围剂量当量率低于加速器机座位于机房北侧时相应关注点的周围剂量当量率。结论18 MV加速器的无迷路调试机房,入口防护门需要同时考虑光子和中子的屏蔽,防护门与两侧墙体有双层搭接时,则防护门外可达到更好的屏蔽防护效果。Objective To study the shielding effect of the protective door of a maze-free debugging room for an 18 MV medical linear accelerator and its influencing factors,and to provide guidance for protection of debugging personal against radioactive occupational disease hazards.Methods The investigation focused on the protective door of a newly constructed maze-free debugging room for an 18 MV medical linear accelerator.The protective door was made of the following shielding materials from inside to outside:2.5 cm steel plate+20 cm lead+41 cm polyethylene containing 5%boron+6 cm lead+2.5 cm steel plate.The right side of the protective door was provided with a groove(commonly known as“door pocket”)lap.With different lap widths,irradiation directions,and installation positions of the accelerator base,FLUKE451P and WENDI II neutron detectors were used to measure the ambient dose equivalent rate of the points of interest outside the protective door.The shielding effect and influencing factors were analyzed.Results When the lap width at both sides of the protective door was 300 mm,the ambient dose equivalent rates outside the protective door were(1.37±0.05)μSv/h on the side with“door pocket”and(4.71±0.11)and(4.19±0.11)μSv/h on the side without“door pocket”.When the primary beam of the accelerator was directed towards the east,the ambient dose equivalent rates at the points of interest outside the protective door were higher than those of the corresponding points of interest when the primary beam was directed towards other directions.When the accelerator base was located on the south side of the machine room,the ambient dose equivalent rates of the points of interest outside the protective door under the same irradiation conditions were lower than those when the accelerator base was located on the north side of the machine room.Conclusion The study of an 18 MV acceleratorand its maze-free debugging room showed that the radiation of photons and neutrons should be taken into consideration whendesigning the prote

关 键 词：加速器机房 无迷路 防护门 屏蔽效果 

分 类 号：X591[环境科学与工程—环境工程]