摘要
目的探讨CT图像截断区域对胸中段食管癌容积调强计划(VMAT)中靶区和危及器官的剂量学影响。方法选取15例胸中段食管癌患的CT图像,设置圆形掩膜使得截断区域体积占手臂体积的10%、20%、30%和40%,得到相应的截断CT,真实CT记为CT0。在CT0上制作2组放疗计划,一组为采用全弧的VMAT_1F,一组为采用避开手臂的三弧VMAT_3F,并将计划复制至4种截断CT。使用Wilcoxon符号秩检验比较不同计划的剂量学差异。结果与CT0中VMAT_1F相比,CT0中VMAT_3F降低肺的Dmean和V_(5),但增加了脊髓的D_(max)、心脏的Dmean和肺的V_(20)。VMAT_3F中,4种截断CT中的剂量学参数与CT0中的没有统计学差异(均P>0.05)。VMAT_1F中,除均匀性指数HI和脊髓D_(max)外,4种截断CT中的剂量学参数与CT0中的均有统计学差异(P<0.05),且剂量学差异随着截断区域体积比的增加而增大。结论临床中应采集完整的CT数据,必要时设置避开截断区域的射野,降低其对剂量学的影响。
Objective To investigate the dosimetric effect of truncated regions in computed tomography(CT)images on the targets and organs at risk in volumetric modulated arc therapy(VMAT)for middle thoracic esophageal cancer.Methods CT images of 15 patients with middle thoracic esophageal cancer were selected.Circle masks were used to make the volume of the truncated region account for 10%,20%,30%,and 40%of the arm volume,and the corresponding truncated CT images were obtained.The real CT was denoted as CT0.Two radiotherapy plans were made on CT0.One plan was VMAT_1F with full arcs,and the other one was VMAT_3F with arm avoidance.The plans were transplanted to four truncated CT,respectively,and the dosimetric differences between different plans were compared using Wilcoxon signed-rank test.Results Compared with VMAT_1F in CT0,Dmeanand V_(5)of the lung decreased in VMAT_3F,but D_(max)of the spinal cord,Dmeanof the heart,and V_(20)of the lung increased.In VMAT_3F,there was no statistically significant difference between the dosimetric parameters in the four truncated CT and those in CT0(all P>0.05).In VMAT_1F,except for homogeneity index and D_(max)of the spinal cord,the dosimetric parameters in four truncated CT were significantly different from those in CT0(P<0.05).The dosimetric difference increased with the increase in truncated region-to-volume ratio.Conclusion Complete CT data should be collected in clinical practice,and the radiation field avoiding the truncated regionshould be set if necessary to reduce the influence of the truncated region on dosimetry.
作者
谢凯
张恒
奚谦逸
张钒
张赛
高留刚
孙佳伟
林涛
眭建锋
倪昕晔
XIE Kai;ZHANG Heng;XI Qianyi;ZHANG Fan;ZHANG Sai;GAO Liugang;SUN Jiawei;LIN Tao;SUI Jianfeng;NI Xinye(Department of Radiotherapy,Nanjing Medical University Affiliated Second People’s Hospital of Changzhou,Changzhou 213000 China;Jiangsu Province Engineering Research Center of Medical Physics/Center for Medical Physics Nanjing Medical University/Key Laboratory of Medical Physics,Changzhou 213000 China)
出处
《中国辐射卫生》
2022年第6期724-730,共7页
Chinese Journal of Radiological Health
基金
常州市应用基础研究(CJ20200099,CJ20210128)
常州市卫健委青苗人才(CZQM2020075,CZQM2020067)
江苏省医学物理工程研究中心项目(苏发改高技发(2021)1368号)
江苏省卫健委面上项目(M2020006)。
关键词
食管癌
容积旋转调强放疗
截断CT
FOV
剂量学参数
Esophageal cancer
Volumetric modulated arc therapy
Truncated CT
FOV
Dosimetric parameters
