基于体素的射波刀肺追踪剂量覆盖率体积直方图研究  

Dose-coverage rate volume histogram for lung tracking with Cyberknife based on voxels

作　　者：张建平 ZHANG Jianping(Department of Radiation Oncology,Fujian Medical University Union Hospital,Fuzhou 350001,China;Fujian Clinical Research Center for Radiology and Radiotherapy for Digestive,Hematological and Breast Malignancies,Fuzhou 350001,China)

机构地区：[1]福建医科大学附属协和医院放射治疗科,福建福州350001 [2]福建省消化、血液系统与乳腺恶性肿瘤放射与治疗临床医学研究中心,福建福州350001

出　　处：《中国医学物理学杂志》2024年第11期1343-1348,共6页Chinese Journal of Medical Physics

基　　金：福建省中青年教师教育科研项目(JAT200165)。

摘　　要：目的:基于体素计算分次间射波刀肺追踪的剂量覆盖率体积直方图(CVH),并探讨肿瘤体积、解剖位置与CVH鲁棒性之间的相关性。方法:回顾性分析外周型肺癌患者55例(上肺26例,中肺22例,下肺7例),共339分次。所有患者均采用射波刀(VSI型)Xsight Lung追踪(2-view)方式进行治疗,拍片时间间隔为60 s。在射波刀的动态追踪系统(MTS)中记录的呼吸追踪数据均转化为患者坐标系。以射波刀治疗时产生的log文件为基础,基于体素利用MATLAB科学计算软件计算不同外扩范围下的CVH,并讨论肿瘤体积、解剖位置与CVH鲁棒性之间的相关性。结果:采用95%靶区覆盖率(C95)大于95%即C95>95%作为是否满足临床要求的评价指标,满足临床要求的计划在整个治疗疗程内并非所有治疗分次都能达到评价指标。对于同一外扩范围,其CVH由大到小依次为:上肺>中肺>下肺。另外,对于中、下肺而言,肿瘤外扩5 mm并不能满足临床评价指标即C95>95%。肿瘤体积和治疗过程中CVH的鲁棒性之间呈负相关。肿瘤体积越大治疗过程中的CVH波动越小,反之,肿瘤体积越小,治疗期间覆盖率的不确定度越大,鲁棒性越差。对于下肺肿瘤,上述现象更加明显。另外,随着外扩范围的增加,CVH的鲁棒性也逐渐上升。结论:对于小体积和下肺肿瘤的治疗,平均覆盖率小于大体积和上肺肿瘤,治疗过程中应根据患者肿瘤体积、位置等因素综合考虑外放范围,以进一步提高临床疗效。Objective To calculate the inter-fractional dose-coverage rate volume histogram(CVH) of Cyberknife Xsight lung tracking based on voxels,and to investigate the correlation among tumor volume,anatomical location and CVH robustness.Methods A retrospective analysis was conducted on 55 peripheral lung cancer patients,with 26 in upper lobe,22in middle lobe and 7 in lower lobe,and there were 399 fractions.All patients were treated with Cyberknife(VSI) Xsight Lung tracking(2-view),with a scanning time interval of 60 s.The respiration tracking data recorded in Cyberknife motion tracking system were converted into patient coordinates.Based on the log files generated during Cyberknife treatment,the CVH of different margins were calculated with MATLAB on a voxel scale,and the correlation among anatomical location,tumor volume and CVH robustness was discussed.Results The target coverage rate(coverage of 95%,C95) greater than95%,that is C95>95%,was taken as the evaluation criterion of whether the clinical requirements were met.Not coverage rate of all fractions met the clinical requirement when an evaluable treatment plan was delivered during treatment course.For the same margin,the value of CVH in order from the largest to the smallest was:upper lobe > middle lobe > lower lobe.The margin of 5 mm won't met the criterion of C95>95% for lung cancer in middle and lower lobes.There was a negative correlation between tumor volume and CVH robustness during treatment.The larger the tumor size,the smaller the fluctuation of CVH;conversely,the smaller the tumor size,the greater the uncertainty of coverage during treatment and the poorer the robustness.For lower lobe lung tumors,the above phenomenon was more obvious.Additionally,CVH robustness improved with increasing margin.Conclusion For small volume and lower lobe lung tumors,the average coverage rate is lower than that of large volume and upper lobe lung tumor,and the margin should be comprehensively considered based on the factors such as tumor volume and location for further impro

关 键 词：射波刀 肺追踪 治疗分次 剂量覆盖率体积直方图 

分 类 号：R811.1[医药卫生—放射医学]