指形电离室在后装放射治疗计划点剂量验证中的应用  

Application of thimble ionization chamber in point dose verification of brachytherapy

作　　者：杨凤 王先良[2] 祁国海[2] 刘敏[2] 黎杰[2] 康盛伟[2] 冯玺[2] 刘明哲[1] YANG Feng;WANG Xianliang;QI Guohai;LIU Min;LI Jie;KANG Shengwei;FENG Xi;LIU Mingzhe(School of Nuclear Technology and Automation Engineering,Chengdu University of Technology,Chengdu 610059,China;Sichuan Cancer Hospital & Institute,Chengdu 610041,China)

机构地区：[1]成都理工大学核技术与自动化工程学院,四川成都610059 [2]四川省肿瘤医院?研究所,四川成都610041

出　　处：《中国医学物理学杂志》2019年第5期506-512,共7页Chinese Journal of Medical Physics

基　　金：四川省重点研发项目(2017GZ0322;2018GZ0197)

摘　　要：目的:探讨用指形电离室进行患者后装放射治疗计划剂量验证的方法及可行性。方法:对自制模体进行CT扫描,将获得的图像导入Oncentra V4.3计划系统。在计划系统上勾画出指型电离室灵敏体积,以此为感兴趣区,感兴趣区的平均剂量认为是测量点的剂量。实验有两个部分:(1)用Oncentra V4.3计划系统在自制模体上制定单管、双管和三管施源器的简单计划,然后在自制模体照射并测量,对比平均剂量与测量值之间的剂量偏差;(2)选取21例患者的治疗计划,在自制模体对应的施源器管道和对应的驻留位置中输入患者计划的驻留时间,对比平均剂量与测量值之间的剂量偏差。结果:简单计划系统计算值和指型电离室测量值之间的最大偏差为-3.5%,21例患者计划系统计算值和测量值之间的偏差均小于5%。结论:可以用指形电离室对后装放射治疗患者的计划进行点剂量验证。Objective To explore the approach and feasibility of using a thimble ionization chamber to carry out dose verification of brachytherapy. Methods The self-made phantom was scanned with CT and the obtained images were imported into Oncentra V4.3 planning system. The region of interest which plotted on the planning system was defined as the sensitive volume of the thimble ionization chamber and the average dose of the region of interest was considered as the dose at the measurement point. This experiment for the dose verification of brachytherapy mainly includes two parts.(1) The simple plans for source applicators, including singletube, doubletube and three-pipe, were made for the self-made phantom with the use of Oncentra V4.3 system, and then the self-made phantom were irradiated for dose measurements. Finally, the dose deviations between the average dose and the measured values were compared.(2) The treatment plans of 21 patients were selected. With the corresponding source applicators and dwelling positions of the self-made phantom, the dwelling time in the treatment plans of patients was adopted for the calculation and measurement. Finally, the dose deviations between the average dose and the measured value were compared. Results The maximum deviation between the calculated values of the planning system and the measured values of the thimble ionization chamber was - 3.5%. The deviations between the measured value and the calculated values in 21 patients were all less than 5%. Conclusion Thimble ionization chamber can be used for the point dose verification of brachytherapy.

关 键 词：宫颈癌 指形电离室 后装放射治疗 剂量验证 计划系统 

分 类 号：R312[医药卫生—基础医学] R144.1