四维锥形束CT对食管癌调强放疗中靶区剂量的影响

摘要

ObjectiveTo evaluate the dosimetric advantages of image-guided radiation therapy(IGRT)using four-dimensional cone-beam computed tomography(4D-CBCT)for esophageal cancer.MethodsSixteen patients with esophageal cancer were enrolled to be planned with IMRT and IGRT plan. The parameters of dose volume histogram(DVH)for targets and organs at risk(OAR)were compared between two techniques. The OAR mainly take lungs and spinal cord into accord .ResultsFor the planning target volume(PTV)of tumor and para-tumor tissues,the mean dose,maximal dose and doses covering 95%volume were similar in IMRT and IGRT plans(P>0.05).However,IGRT plans have lower maximal dose to the planning risk volume of the spinal cord[(38.46±3.34)Gy vs(42.80±7.26)Gy,P<0.05]and lower lung volume received dose of 5 Gy or higher[(50.8±6.8)% VS(62.3±5.7)%,P<0.05]than IMRT plans.ConclusionFor esophageal cancer,IGRT has better spinal cord sparing than IMRT,and can reduce the volume of lung that received dose of 5Gy or higher.And IGRT may provide quality assurance to reduce radiation toxic reactions.%目的：分析四维锥形束CT对食管癌调强放疗中计划靶区及危及器官剂量的影响。方法收集16例食管癌患者，分别设计图像引导放疗计划（IGRT）及非图像引导的调强放疗计划（IMRT），在满足靶区处方剂量要求（95%的体积范围包括PTV95%剂量）的情况下，通过剂量体积直方图（DVH）评价和比较两个计划的双肺、脊髓和计划靶区（PTV）剂量的差异。结果 IGRT和IMRT两个计划之间肿瘤计划靶区的最大剂量、最小剂量、平均剂量、包含95％靶区的剂量均很接近，差异无统计学意义（P>0.05），但IGRT计划中脊髓计划区的最高受量明显较IMRT的低[（38.46±3.34）Gy vs（42.80±7.26）Gy，P<0.05]；>5Gy的双肺受照体积为（50.8±6.8）％，也明显较IMRT计划的（62.3±5.7）％低，差异均有统计学意义（P<0.05）。结论 IGRT技术在食管癌中的应用减少正常组织的体积及受量，有可能提高临床疗效，为减轻放疗毒性反应提供质量保证。