放射治疗中肿瘤靶区勾画的主观差异性分析

Analysis of subjective variability in gross tumor volume (GTV) delineation during radiotherapy

为了解医生的主观因素在肿瘤靶区(GTV)勾画中产生差异性并分析其原因,对肿瘤处在身体不同部位的12例病人的CT定位图像,组织了来自放射治疗和影像诊断的6位医师进行了GTV勾画,计算病人GTV的体积值及其变化范围,比较两个学科和两次勾画所产生的差异性。结果表明,9位病人GTV体积最大值/最小值比值<2,3位病人的项比值>2;16%的体积值对体积平均数的变动范围>±25%。在已知影响准确性的重要客观因素一致的条件下,造成差异性的主要原因是医生间学科的不同,影像科医生比放疗科医生的变异性小、准确性高。因此,在确定GTV时,对于因主诊医生主观因素产生的误差要引起重视,放射治疗医生加强影像诊断学知识学习与协作,建立、完善并认真执行相关的QA与QC规程是解决问题的主要方法。

To assess the subjective variability in gross tumor volume （GTV） delineation by radiation oncologists, six physicians from Departments of Radiotherapy and Radio-diagnosis were invited to delineate the GTV on sequential CT slices twice with one-month interval. The CT images were from 12 cancer patients with different tumor location in their body. The variability of GTV volume value and its difference from inter-speciality and inter-interval were calculated. A high variability of GTV volume was found, the ratio of the largest to the smallest volume was less than 2 in 9 patients, while it was larger than 2 in all the others. As for the change range of GTV volume compared with its mean value in each patient, there were 16% volume values larger than ±25%. With the well-controlled objective influences, there were statistical differences of GTV volume of 3 patients in the inter-speciality variation. The variation within the radiation oncologist was larger than that within the radio-diagnosticians. A large subjective variability in GTV delineation was demonstrated. A better training and cooperation of radiation oncologist, and standardization of the QA and QC approach with guidelines will result in a reduction in this variation of radiotherapy planning.