VitalBeam加速器四种不同治疗床板的剂量衰减特性测量与分析  

Measurement and Analysis of Dose Attenuation Characteristics of Four Different Treatment Couch for VitalBeam Accelerator

作　　者：蓝茂英 杨波[1] 许文伟[1] 吴朱峰 钟振东 伍锐[1] 刘香林 范颖天 孙建聪[1] LAN Maoying;YANG Bo;XU Wenwei;WU Zhufeng;ZHONG Zhendong;WU Rui;LIU Xianglin;FAN Yingtian;SUN Jiancong(Department of Radiotherapy,The First Affiliated Hospital of Guangzhou Medical University,Guangzhou Guangdong 510120,China)

机构地区：[1]广州医科大学附属第一医院放疗科,广东广州510120

出　　处：《中国医疗设备》2022年第4期51-54,58,共5页China Medical Devices

基　　金：广州市临床特色技术项目(2019TS28);全国医学专业学位研究生教育指导委员会研究课题(B1-YX20180307-01)。

摘　　要：目的探讨并比较四种不同加速器治疗床板对VitalBeam加速器四档光子线剂量衰减的影响。方法将固体水模中心与VitalBeam加速器等中心对齐,将需要测量的CIVCO公司两款床板和Qfix公司两款床板分别放置于固体水模上,床板纵向中心轴对齐中间激光线,使用指形电离室测量模体中心剂量。在VitalBeam的6 MV、10 MV、6 FFF和10 FFF四档光子束能量下,选择10 cm×10 cm和5 cm×5 cm射野,机架角为0°~80°(间隔10°测量),测量无床板时和有床板时的剂量,对比得出各个床板在不同入射角度下的衰减系数。结果在VitalBeam加速器的四档光子线能量下,对于10 cm×10 cm和5 cm×5 cm的照射野,CIVCO碳纤维床板的衰减因子为2.10%~8.19%;CIVCO凯夫拉床板的衰减因子为2.73%~8.97%;Qfix Calypso床板的衰减因子为1.49%~6.92%;Qfix KUTI床板的衰减因子为1.92%~7.79%,所有衰减值均在0°~70°之间随入射角度增加而增大。结论四种床板绝大部分入射角度的衰减均超过2%,所有床板均在70°的斜入射时达到最大衰减值,临床中在治疗计划设计时应考虑加速器治疗床对剂量衰减的影响,对不同的治疗床应建立相应的床模型。Objective To investigate and compare the effects of dose attenuation of four different treatment couches on VitalBeam accelerator.Methods The center of the solid water phantom was aligned with the VitalBeam accelerator iso center.Two kinds of couch from CIVCO and Qfix were placed on the solid water phantom respectively.The longitudinal center axis of the couch was aligned with the middle laser line.A thimble chamber was utilized to measure the absolute dose in the phantom.Under VitalBeam’s 6 MV,10 MV,6 FFF and 10 FFF four-level photon beam energy,10 cm×10 cm and 5 cm×5 cm emission fields were selected,and the frame angle was 0°~80°(measured at an interval of 10°).The dose with couch and without couch were measured and the attenuation coefficients of each couch at different gantry angles were compared.Results Under the four different photon energies modes and 10 cm×10 cm and 5 cm×5 cm field sizes of VitalBeam accelerator,the attenuation coefficients of CIVCO carbon couch were 2.10%~8.19%.The attenuation coefficients of CIVCO Kevlar couch were 2.73%~8.97%.The attenuation coefficients of Qfix Calypso couch was 1.49%~6.92%.The attenuation factor of Qfix KUTI couch were 1.92%~7.79%,and all attenuation values were between 0°~70°and increase with the increase of incident angle.Conclusion The attenuation coefficients of most of the incident angles of the four couches were more than 2%,and all the couch plates reach their maximum attenuations at oblique incidence of 70°.The effect of accelerator treatment couch on dose attenuation should be considered in the design of clinical treatment plan,and the corresponding couch model should be established for different treatment couch.

关 键 词：医用直线加速器 碳纤维床板 凯夫拉床板 放射治疗剂量 衰减系数 

分 类 号：R815.6[医药卫生—放射医学] R312[医药卫生—临床医学]