容积旋转调强在局部晚期鼻咽癌放疗中的剂量学特点

目的:研究容积旋转调强（VMAT）放射治疗技术在局部晚期鼻咽癌放疗中的剂量学特点。方法:选取70例局部晚期鼻咽癌患者，分别对入组患者进行等效均匀剂量优化+双弧VMAT计划设计（EUD组）和剂量-体积优化+双弧VMAT计划设计（DV组），比较两种计划的靶区和部分危及器官（OAR）剂量参数和截面剂量分布情况。结果:EUD组均匀性指数和适形度指数均显著低于DV组，靶区和OAR剂量参数显著低于DV组（P<0.05），尤其是EUD组脑干区域最高剂量在52 Gy以下，显著降低了治疗中损伤脑干的风险；EUD组靶区剂量分布更加均匀，能够减少靶区外高剂量分布和颈部高剂量体积。结论:将VMAT技术应用于局部晚期鼻咽癌放疗中时，采取等效均匀剂量优化方法，能够提升靶区均匀性与适形度，有助于改善肿瘤局部控制率，并且能够降低OAR接受剂量，保护作用更加显著。

Dosimetric characteristics of volumetric modulated arc therapy for locally advanced nasopharyngeal carcinoma

Abstract: Objective To study the dosimetric characteristics of volumetric modulated arc therapy (VMAT) technique in radiotherapy for locally advanced nasopharyngeal carcinoma (NPC). Methods Seventy patients with locally advanced NPC were enrolled in the study. Both equivalent uniform dose optimization + double-arc VMAT plan (EUD group) and dose-volume optimization + double-arc VMAT plan (DV group) were designed for each patient. The dose parameters and cross section dose distributions of target areas and some organs-at-risk (OAR) were compared between two plans. Results The homogeneity index and conformity index of EUD group were significantly lower than those of DV group, and the dose parameters of target areas and OAR were significantly lower than those of DV group (P<0.05), especially the highest dose of brainstem in EUD group was lower than 52 Gy, which significantly reduced the risk of brainstem injury during treatment. Moreover, the dose distribution of target areas in EDU group was more uniform, which reduced the high dose distribution outside the target areas and decreased the high-dose volume in the neck. Conclusion When VMAT technique is applied in the radiotherapy for locally advanced NPC, using equivalent uniform dose optimization can not only improve the homogeneity and conformity of target areas, which is helpful for the improvement of the local control rate of the tumor, but also reduce the dose of OAR, with more significant OAR sparing.