肺癌立体定向放疗偏中心计划设计剂量学研究  

A dosimetric study on off-target isocenter plans for stereotactic body radiotherapy of lung cancer

作　　者：杨晓喻[1] 赵于前[2] 杨振[1] 李书舟 邵其刚 曹瑛 Yang Xiaoyu;Zhao Yuqian;Yang Zhen;Li Shuzhou;Shao Qigang;Cao Ying(Oncology Department,National Clinical Research Center for Geriatric Disorders/Xiangya Hospital,Central South University,Changsha 410008,China;School of Automation,Central South University,Changsha 410083,China)

机构地区：[1]中南大学湘雅医院肿瘤科国家老年疾病临床医学研究中心,长沙410008 [2]中南大学自动化学院,长沙410083

出　　处：《中华放射医学与防护杂志》2023年第8期633-638,共6页Chinese Journal of Radiological Medicine and Protection

基　　金：国家自然科学基金(12005306,62076256);湖南省自然科学基金(2021JJ40960,2021JJ40966,2022JJ30976)。

摘　　要：目的研究不同程度的偏中心计划对肺癌立体定向放疗(SBRT)计划质量和执行准确度的影响,为肺癌SBRT的临床计划设计提供参考。方法首先,选取10例肺癌SBRT患者,将计划等中心置于肿瘤质心位置,设计等中心参考计划。将计划等中心置于偏离肿瘤质心1、3、5、8及10 cm位置,设计偏中心计划,共计60个,分析这些偏中心计划相对于参考计划的剂量学差异。然后,引入不同程度的位置误差(0~5 mm),利用Octavius 4D高分辨率剂量验证系统,测量这些计划的伽马通过率(GPR),完成240次计划验证,分析参考计划和偏中心计划的执行准确度对位置误差的鲁棒性。结果偏中心计划的剂量梯度指标略差于等中心计划,差异无统计学意义(P>0.05)。随着偏中心距离增加,正常肺平均剂量(MLD)和V20以及支气管Dmax略微有升高趋势。MLD在偏中心距离1、3和10 cm,较等中心计划分别升高了0.8%、0.8%和1.9%,差异具有统计学意义(z=-2.34~-1.99,P<0.05),V20在偏中心距离1、5和10 cm,较等中心计划分别增加了2.0%、2.5%和3.7%,差异具有统计学意义(z=-2.11~-1.99,P<0.05)。当位置误差达到5 mm时,偏中心距离5 cm及以上计划的GPR平均降幅在1.0%以上,最高可达3.5%,差异均具有统计学意义(z=2.13~2.75,P<0.05)。结论偏中心计划的剂量学质量略差于等中心参考计划,其执行准确度对位置误差的鲁棒性变差。应尽量避免偏中心距离过大的(≥5 cm)计划设计与治疗。Objective To investigate the effects of off-target isocenter plans with different offtarget distances on the plan quality and delivery accuracy of stereotactic body radiotherapy(SBRT)for lung cancer,aiming to provide a reference for the clinical plan design of SBRT for lung cancer.Methods For 10 lung cancer patients treated with SBRT,isocenter reference plans were designed by setting the plan isocenters at the mass centers of tumors and 60 off-target isocenter plans by setting the isocenters at distances of 1,3,5,8,and 10 cm from the mass centers of tumors.The dosimetric differences between the off-target isocenter plans and the reference plans.Subsequently was analyzed,under different positional errors(0-5 mm).The gamma pass rates(GPRs)of these plans were measured using the Octavius 4D high-resolution dose verification system,and 240 verifications of these plans were completed.The robustness of the delivery accuracy of the reference plans and off-target isocenter plans were analyzed under different positional errors.Results The off-target isocenter plans yielded slightly worse dose gradient indices than the isocenter reference plans,but there was no statistically significant differences.With an increase in the off-target distance,the mean lung dose(MLD),V20 of normal lungs,as well as the Dmax of bronchi,showed slight upward trends.Compared with the isocenter reference plans,the MLD of the offtarget isocenter plans increased by 0.8%,0.8%,and 1.9% at off-target distances of 1,3,and 10 cm,respectively,with statistically significant differences(z=-2.34 to-1.99,P<0.05),and the V20 of the off-target isocenter plans increased by 2.0%,2.5%,and 3.7%at off-target distances of 1,5,and 10 cm,respectively,with statistically significant differences(z=-2.11 to-1.99,P<0.05).In the case of a positional error of up to 5 mm,the GPRs of plans with off-target distances of 5 cm and above decreased by more than 1.0%on average and up to a maximum of 3.5%,showing statistically significant differences(z=2.13-2.75,P<0.05).Conclusions Comp

关 键 词：肺癌 SBRT 偏中心计划设计 执行准确度 

分 类 号：R734.2[医药卫生—肿瘤] R730.55[医药卫生—临床医学]