瓦里安IGRT治疗床对调强放疗剂量的影响  

Dosimetric impact of Varian IGRT treatment couch on intensity-modulated radiotherapy

作　　者：叶逢松[1] 吴魁[2] 吴爱菊[1] 

机构地区：[1]丽水市人民医院放疗科,浙江丽水323000 [2]浙江大学医学院附属第二医院放疗科,浙江杭州310009

出　　处：《中国医学物理学杂志》2016年第4期430-432,共3页Chinese Journal of Medical Physics

摘　　要：目的：射线经过加速器治疗床有一定的衰减,对靶区和危及器官的剂量有一定影响。本文探讨Varian Exact IGRT治疗床对调强放射治疗（IMRT）剂量的影响。方法：选取10例肺癌患者,使用Eclipse计划系统设计两组IMRT计划,第一组计划考虑治疗床的影响,第二组计划去掉治疗床后重新计算剂量分布,比较两组计划剂量分布。并对两组计划进行剂量验证,比较γ因子符合度指数（GAI）。结果：去掉治疗床后,计划靶区平均剂量升高3.1%,其余重要危及器官受到剂量也有增加。剂量验证的GAI结果表明,当射野先经过治疗床再到达靶区时,考虑治疗床的影响通过率更好（GAI为93.9%～100%）。结论：在设计IMRT计划时,有必要加入治疗床板,使计算结果与实际剂量分布更加吻合。Objective The beam is attenuated by the treatment couch during radiotherapy, having some impacts on the dose of target volumes and organs at risk（OARs）. The impacts of Varian Exact IGRT treatment couch on intensity-modulated radiotherapy（IMRT） are discussed in the paper. Methods Ten patients with lung cancer were selected. Eclipse planning system was used to design two IMRT plans for each patient. The impact of treatment couch was considered in one plan, while the dose distribution was calculated again after removing the treatment couch in the other plan. The dose distributions of two plans were compared,and the dose verifications were performed for the two plans to compare the gamma agreement index（GAI）. Results After removing the treatment couch, the average dose of planning target volume increased by 3.1% and that of OARs were also increased. The GAI comparison showed when the beam passed through treatment couch and then reached the target volume, the pass rate of the plan considering the impacts of treatment couch was better, and the GAI was 93.9%-100%. Conclusion Treatment couch is necessary in the IMRT plan design for agreeing calculated results with actual dose distribution.

关 键 词：治疗床 调强放射治疗 剂量分布 γ因子 肺癌 

分 类 号：R737[医药卫生—肿瘤] R312[医药卫生—临床医学]