基于最优自动勾画的放疗计划剂量学评估

摘要

Objective To evaluate the dosimetric errors of organs-at-risk (OARs) induced by the optimal auto-segmentation using Mim Maestro based on dose calculation and measurement.Methods The Mim atlas library composed of 240 nasopharyngeal carcinoma,breast cancer,and rectal cancer patients that were retrospectively selected was used for the auto-segmentation of OARs on the CT images of corresponding regions in 76 patients.Relative to the manual contouring,one optimal case was selected from each site based on conformity index (CI),mean distance to conformity (MDC),relative volume difference (Dv％),DICE,sensitivity index (Se.Idx),and inclusion index (Inc.Idx).Treatment plans were made to satisfy the DVH constraints of OARs based on auto-contours,and then the dose errors to the actual organs were evaluated in terms of calculation and measurement.The paired t-test (normal distribution) or rank sum test (non-normal distribution).Results Significant differences were observed in the 76 patients between the manual and automated segmentation (P＜0.05).For the optimal cases,the DICE index of various OARs ranged from 0.43 to O.98,and 73％(16/22) of DICE values were higher than 0.70.The calculated dose errors to various OARs were (-1.15±15.94)％(95％ CI:-8.21％ to 5.92％) (mean dose) and (-6.53±21.13)％ (95％ CI:-15.90％ to 2.84％) (maximum dose).The measured dose errors were (-2.43± 24.52)％ (95％ CI:-13.30％ to 8.44％)(mean dose) and (-3.38±20.87)％(95％ CI:-12.63％ to 5.87％)(maximum dose).Conclusion Without human interference,even the optimal auto-segmentation results are not clinically acceptable for treatment planning.%目的 从计算和测量层面评价MimMaestro最优自动勾画结果导致OAR受量误差.方法 利用240例鼻咽癌、乳腺癌和直肠癌数据建立Mim模板库完成76例相应部位CT数据OAR自动勾画,并从中各选出1例与原手工勾画结构最接近的“最优”病例.评价依据包括CI、适形均距(MDC)、体积差(Dv％)、相似系数(DICE)、敏感指数(Se.Idx)、包容指数(Inc.Idx).基于自动勾画的OAR分别设计放疗计划使其表观DVH满足临床需求,然后评价该计划在计算与测量层面导致真实OAR受量的误差.配对t检验(正态分布)或秩和检验(非正态分布)差异.结果 76例自动分割与人工勾画结果不同(P＜0.05),其中最优病例各器官DICE值为0.43～0.98,DICE＞0.70的占73％ (16/22).由此导致OAR受量误差的理论值为(-1.15± 15.94)％,95％ CI为-8.21％～5.92％(平均剂量)和(-6.53±21.13)％,95％ CI为-15.90％ ～2.84％(最大点剂量);实测值为(-2.43±24.52)％,95％ CI为-13.30％ ～8.44％(平均剂量)和(-3.38±20.87)％,95％ CI为-12.63％ ～5.87％(最大点剂量).结论 在缺乏人工干预情况下,即使基于最优自动分割结果的放疗计划也无法直接满足临床需求.