变形配准与经验计算剂量累加法用于肺癌放疗计划累加剂量计算的研究

目的 应用变形配准功能评价肺癌患者放疗计划中正常组织和危及器官的累加剂量,并与经验计算剂量累加法进行比较.方法 回顾性分析10例肺癌患者,放疗前制定了三维适形或调强治疗计划,放疗过程中重新行CT模拟,并重新设计相同的治疗计划.采用Mimvista软件,运用变形配准,分别在2次CT图像上进行剂量累加.采用经验计算剂量累加法,计算2次放疗计划的正常组织和危及器官的累加剂量,分别对两种方法的双侧肺组织、心脏及脊髓的受照剂量体积以及平均剂量等参数,进行比较.结果 定位和复位图像采用相同的计划方式时,两种方法所得正常组织和危及器官的累积受照体积和剂量等参数差异无统计学意义,仅右肺的平均剂量除外(t=2.98,P＜0.05).结论 变形配准法可以准确评价肺癌患者多次放疗计划中正常组织和危及器官的累加剂量.肺癌患者的靶区变化不大并且采用相同的计划方式时,应用经验计算剂量累加法,可粗略评价肺和心脏等正常组织和危及器官的剂量体积.

Application of deformable registration and empirical calculation method to calculate the accumulated dose for normal tissues and organs at risks in lung cancer radiotherapy plans

Objective To evaluate the accumulated doses to normal tissues and organs at risks (OARs) of patients with lung cancer in radiotherapy plans by using the deformable registration method,and make comparison with the empirical calculation method. Methods Ten patients with lung cancer were analyzed retrospectively. 3D-CRT or IMRT plans were designed before treatment. CT to simulator was rescanned and the same treatment plan was redesigned during radiotherapy. Based on the deformable registration method, the Mimvista software was used to calculate the accumulated doses to normal tissues and OARs in two CT images respectively. The empirical estimation algorithm was calculated by the linear relationship between the fractions and the total prescribed dose. Results The target coverage of patients had no significant difference in two plans. There were no significant differences in all the dose volume parameters for normal tissues and OARs, except the mean dose to right lung(t=2.98,P<0.05) when the the same plan was conducted in position-setting and reposition CT images. Conclusions The empirical estimation for the accumulated dose could be used to evaluate the dose and volume parameters for normal tissues and OARs in lung cancer by the same plan.