VitalBeam直线加速器机房辐射屏蔽效果研究  

Analysis of shielding effect of the radiation of the machine room of VitalBeam linear accelerator

作　　者：王宇翔 高楠 刘志鹏 王远远[1] WANG Yu-xiang;GAO Nan;LIU Zhi-peng(Department of Clinical Physics and Technology,Hefei Ion Medical Center,Ion Medical Center,The First Affiliated Hospital of University of Science and Technology of China,Hefei 231283,China)

机构地区：[1]中国科学技术大学附属第一医院离子医学中心(合肥离子医学中心)临床物理技术科,安徽合肥231283 [2]中国科学技术大学附属第一医院离子医学中心(合肥离子医学中心)医学工程装备部,安徽合肥231283

出　　处：《中国医学装备》2023年第5期17-21,共5页China Medical Equipment

摘　　要：目的:探讨测量配备多档能量模式的医用直线加速器机房辐射屏蔽效果的影响因素,为放射工作场所辐射防护检测方法提供参考。方法:在瓦里安VitalBeam直线加速器机房的0°和90°机架角度、有无散射体、6MV(有均整过滤器)、10 MV、15 MV、6 MV无均整过滤器(FFF)、10 MVFFF共3档能量5个模式的条件下,选取防护门外30 cm处平面上A~F点、主屏蔽墙外G点、次屏蔽墙外H~I点、控制室内J点和水冷机室K点共计11处关注点位,进行X/γ射线和中子剂量当量率测量,并对测量结果进行理论分析。结果:15 MV能量档有均整过滤器条件下,各关注点位在各种测量条件下的X/γ射线剂量当量率测量值均高于其他能量模式;防护门外A~E点在15 MV能量档,机架角0°时的X/γ射线剂量当量率测量值明显高于机架角90°时的测量结果。对于机房周边感兴趣点G~K点,除主屏蔽墙外30 cm处的G点在机架角0°时测量值低于机架角90°时的测量值外,其他点位结果无明显差异;放置散射体后,防护门外A~E点的X/γ测量值要高于未放置散射体时的结果,对于机房周边感兴趣点G~K点的测量值基本处于本底(0.08μSv/h)范围;仅在防护门F点处检测出有效中子剂量率,且与射线能量和剂量率成正比关系。机架角在0°时的中子剂量当量率低于机架角90°时的结果。结论:在测量档位、模式选择的优先级上,15 MV有均整器模式要优先于10 MV FFF模式。对于防护门的防护检测,建议选择0°机架角测量;对于主次屏蔽墙的防护检测,应选择机头射线正对的角度进行测量。对于X/γ射线测量,在等中心处设置散射体,导致防护门处的散射线剂量增加,但对主次屏蔽墙外、控制室内及水冷机室内的剂量影响不大。针对中子线进行防护检测时应选择最高能量档测量,无需放置散射体,机架角可选择在90°,其可作为防护检测方法的参考,选择最合适的测量条件,从�Objective:To explore the influence factors of the radiation shielding effect of the room of a medical linear accelerator equipped with multiple energy modes,so as to provide a reference for the test methods of domestically relevant departments for radiation protection at radiation workplace.Methods:A total of 11 points of interest,which included points A-F on the plane 30 cm away outside the shielding door,point G on the outside of the main shielding wall,points H-I on the outside of the secondary shielding wall,point J in the control room and point K in the water cooling room,were selected.The measurement conditions included two different gantry angles(0°and 90°),with or without scatterers,and 5 modes using 3 different energy levels of a Varian VitalBeam linear accelerator,including 6 MV(with flatness filter,the same below),10 MV,15 MV,6 MV FFF(flatness filter free,the same below)and 10 MV FFF.And then,the measurements of the equivalent dose rate of X/γray and neutron dose were conducted,and the theoretical analysis of the measurement results was conducted.Results:The measured value of the equivalent dose rate of X/γray of each measured condition of each point of interest under 15 MV energy level with flatness filter was higher than that of other energy modes.Under 15 MV mode,the measured value of the equivalent dose rate of X/γray of points A-E outside of the shielding door at gantry angle 0°was significantly higher than that of gantry angle 90°.For points G-K surrounding the accelerator room,there were no significant differences in the measured results of other points between gantry angle 0°and gantry angle 90°except point G at 30 cm outside of the main shielding wall.The measured values of X/γat points A-E outside the shielding door with the scatterer were higher than those without the scatterer.The measured values of points G-K surrounding the accelerator room were basically within the background(0.08μSv/h).The effective neutron dose rate was only found at point F of the protection door and showed

关 键 词：辐射屏蔽 防护检测 医用加速器 电离辐射 

分 类 号：R814[医药卫生—影像医学与核医学]