Abstract

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

Author(s):: XU Zhuohua; HUANG Haixin; YANG Hui; WU Sibei; JIANG Zhou; LU Ying; The Second Cancer Ward, the Fourth Affiliated Hospital of Guangxi Medical University, Liuzhou 545007, China

Keywords:: Keywords: volumetric modulated arc therapy radiotherapy locally advanced nasopharyngeal carcinoma equivalent uniform dose dosimetry

Abstract:: 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.