Compass在直肠癌术前调强放射治疗三维剂量验证中的应用

摘要

目的:探讨Compass系统在直肠癌术前调强放射治疗三维剂量验证中的临床应用.方法:选取10例直肠癌术前放疗患者在Pinnacle 9.10中进行优化设计,照射野采用七野扇形分布,利用Compass提供的剂量计算(CDD)和剂量重建(RDD)两种方法验证临床靶区(PTV)及危及器官的体积γ通过率、D95％、D50％、D2％、Dmean等参数.结果:γ通过率:靶区与危及器官CDD-TPS均大于98.5％,且CDD-TPS均高于RDD-TPS.PTV和膀胱γ通过率差异显著(t=2.731、2.298,P＜0.05).剂量体积差异:PTV的D2％、膀胱和右侧股骨头的Dmean剂量差异显著(t=-4.280、-2.582、-2.582,P＜0.05).同时PTV的D50％、D2％、左右侧股骨头的Dmean剂量差异CDD-TPS更大.结论:Compass系统提供的剂量验证方法和三维剂量偏差以及γ通过率等剂量评估指标,能够科学合理评估直肠癌术前调强放射治疗计划,具有重要的临床意义.%Objective To investigate the clinical application of Compass system in the three-dimensional (3D) dose verification of preoperative intensity-modulated radiotherapy (IMRT) plan for patients with rectal cancer.Methods Ten preoperative IMRT plans for rectal cancer were optimized with Pinncale 9.10 treatment planning system (TPS).The irradiation field in plans was seven fields showing fan-shaped distribution.Two kinds of dose verification methods in Compass system,namely dose calculation and dose reconstruction,were separately used to obtain computed dose distribution (CDD) and reconstructed dose distribution (RDD) for verifying the Gamma passing rate,D95％,D50％,D2％,and Dmean of the planning target volume (PTV) and organs-at-risk.Results The Gamma passing rates of PTV and organs-at-risk from CDD-TPS were greater than 98.5％,meanwhile,the rates from CDD-TPS were higher than those from RDD-TPS.The differences between CDD-TPS and RDD-TPS in the Gamma passing rates of PTV and bladder were statistically significant (t=2.731,2.298;P＜0.05).The D2％ of PTV and the Dmean of the bladder and the right femoral head between CDD-TPS and RDD-TPS were also statistically significant (t=-4.280,-2.582,-2.582;P＜0.05).Compared with RDD-TPS,CDD-TPS showed greater D50％,D2％of PTV and Dmean of the left and fight femoral head.Conclusion The dose verification and evaluation methods,three-dimensional dose deviation and Gamma passing rate provided by Compass system can reasonably verify the preoperative IMRT plan for rectal cancer,with clinical significance.