基于Calypso电磁实时跟踪系统的4D剂量验证  

4D dose verification based on Calypso electromagnetic real-time tracking system

作　　者：蔡春雅 戴振晖 张白霖 朱琳 招什武 杨耕 朱远湖 李飞 王学涛 CAI Chunya;DAI Zhenhui;ZHANG Bailin;ZHU Lin;ZHAO Shiwu;YANG Geng;ZHU Yuanhu;LI Fei;WANG Xuetao(The Second Affiliated Hospital of Guangzhou University of Chinese Medicine,Guangzhou 510006,China)

机构地区：[1]广州中医药大学第二附属医院,广东广州510006

出　　处：《中国医学物理学杂志》2019年第5期513-516,共4页Chinese Journal of Medical Physics

基　　金：广东省科技厅自筹经费类项目(2017ZC0165);广东省医学科研基金(A2019196)

摘　　要：目的:研究基于Calypso电磁实时跟踪系统的4D剂量验证的可行性,评估Calypso引导对运动靶区放疗剂量精度提高的有效性。方法:将5 cm×5 cm、10 cm×10 cm方野、直径d=10 cm圆形野以及5例IMRT、5例VMAT放疗计划移植到Delta4三维剂量验证系统,使用自主呼吸运动平台搭载Delta4模体进行SI方向上周期(T)=5 s,振幅(A)=±10 mm的往复运动,分别比较静态、动态无跟踪,以及使用Calypso实时跟踪系统运动阈值分别为±2、±3、±5 mm情况下Delta4实测的剂量分布和治疗计划系统剂量分布。结果:静态、动态测量Calypso运动阈值为±2、±3、±5 mm以及动态无跟踪时计划γ通过率的平均值分别为(97.5±2.4)%、(95.9±2.8)%、(93.9±3.8)%、(86.2±8.6)%、(65.0±11.1)%;与静态射野平均γ通过率比较,使用Calypso动态运动阈值为±2、±3 mm时γ通过率差异无统计学意义(P>0.05), Calypso动态运动阈值为±5 mm与动态无跟踪时γ通过率差异具有统计学差异(P<0.05)。结论:对于胸腹部肿瘤患者,基于Calypso实时电磁跟踪,结合Delta4三维验证系统对运动靶区进行实时4D剂量验证是可行的,使用Calypso跟踪运动肿瘤放疗时,剂量精度有明显提高。Objective To investigate the feasibility of 4D dose verification based on Calypso electromagnetic real- time tracking system and evaluate the effectiveness of using Calypso system to improve the accuracy of radiotherapy dose of motion targets. Methods The fields of 5 cm×5 cm and 10 cm×10 cm, a circle field of 10 cm in diameter, 5 cases of IMRT plans and 5 cases of VMAT plans were transplanted to Delta4 three-dimensional dose verification system, and the Delta4 phantom was placed on the self-developed respiratory motion stage to simulate the respiratory in SI direction. The period of the respiratory motion stage was set to 5 s and the amplitude was ±10 mm. Dose distributions obtained with Delta4 software under the static, dynamic non- tracking and Calypso tracking with the motion thresholds of ± 2,± 3 and ± 5 mm were compared with the dose distributions obtained with treatment planning system. Results The average gamma passing rates of the static, Calypso tracking with the motion thresholds of ±2,±3 and ±5 mm, and dynamic non-tracking were (97.5±2.4)%,(95.9±2.8)%,(93.9±3.8)%,(86.2±8.6)% and (65.0±11.1)%, respectively. No significant difference was found in the gamma passing rates between static field and Calypso tracking with the motion thresholds of ±2 and ±3 mm (P>0.05). However, there was statistical difference between Calypso tracking with the motion threshold of ±5 mm and dynamic non-tracking (P<0.05). Conclusion For patients with thoracic and abdominal tumors, using the combination of Calypso electromagnetic real-time tracking system and Delta4 three-dimensional verification system to perform the real-time 4D dose verification of the motion targets is proved to be feasible. The dose accuracy is significantly improved while using Calypso tracking during radiotherapy.

关 键 词：呼吸运动 4D剂量验证 实时跟踪 Calypso系统 

分 类 号：R312[医药卫生—基础医学] TL72[核科学技术—辐射防护及环境保护]