非共面容积旋转调强在食管癌治疗中的应用

Application of non-coplanar volumetric modulated arc therapy for esophageal cancer

目的:研究非共面容积调强(VMAT)在食管癌治疗中的应用前景。方法:选取15例2017年9月至12月间收治的局部晚期胸段食管癌患者,分别设计共面调强、非共面调强和非共面VMAT计划,分析非共面VMAT相对于共面调强和非共面调强靶区和危及器官的剂量分布情况。结果:非共面VMAT、共面调强和非共面调强都可以达到靶区剂量覆盖的要求,但非共面VMAT在适形度指数和均匀性指数上显著优于非共面调强(P<0.05);在脊髓Dmax上,非共面VMAT均显著优于共面调强和非共面调强(P<0.05);在肺V5、V20、V30、Dmean上,非共面VMAT也显著优于共面调强(P<0.05);在心脏的保护上,非共面VMAT在V30、V40上和共面调强、非共面调强之间没有统计学差异。结论:在食管癌放疗中,非共面VMAT有助于提高靶区的适形度指数和均匀性指数,同时降低肺和脊髓的受照射剂量和体积,有助于降低放射性肺炎以及放射性脊髓炎发生的概率。

Objective To investigative the application prospect of non-coplanar volumetric modulated arc therapy(VMAT)in treatment for esophageal cancer.Methods Fifteen patients with locally advanced thoracic esophageal cancer who were admitted from September to December 2017 were enrolled in this study.Coplanar intensity-modulated radiotherapy(IMRT),non-coplanar IMRT and non-coplanar VMAT plans were designed for each patient.The dose distributions of target areas and organs-at-risk between non-coplanar VMAT and coplanar IMRT or non-coplanar IMRT were analyzed.Results All the 3 plans met the requirements of target dose coverage,but non-coplanar VMAT had significant advantages over non-coplanar IMRT in homogeneity index and conformity index(P<0.05).The Dmax of spinal cord of non-coplanar VMAT was significantly lower than that of coplanar IMRT and non-coplanar IMRT(P<0.05);and non-coplanar VMAT was superior to coplanar IMRT in the V5,V20,V30 and Dmean of the lung(P<0.05).No statistical difference was found in the V30 and V40 of the heart between non-coplanar VMAT and IMRT.Conclusion For patients with esophageal cancer,non-coplanar VMAT can improve the conformity index and homogeneity index of target areas and reduce the dose and irradiated volume of the lung and spinal cord,thereby reducing the probabilities of radiation pneumonitis and radioactive spinal cord.