Volumetric modulated arc therapy for nasopharyngeal carcinoma: A dosimetric comparison with TomoTherapy and step-and-shoot IMRT
Volumetric modulated arc therapy for nasopharyngeal carcinoma: A dosimetric comparison with TomoTherapy and step-and-shoot IMRT
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DOI：
10.1016/j.radonc.2011.11.017
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发表时间：
2012-09-01
影响因子：
5.7
通讯作者：
Wang, Chun-Wei
中科院分区：
文献类型：
--
作者：
Lu, Szu-Huai;Cheng, Jason Chia-Hsien;Wang, Chun-Wei
目的：容积调制式弧形放射治疗（VMAT）是一种利用直线加速器进行动态调制式旋转放射治疗的新技术。本研究的目的是比较VMAT与螺旋断层放射治疗（HT）和分步调强放射治疗（IMRT）对鼻咽癌（NPC）患者的危险器官（OARs）的保护作用、剂量学质量和输送效率。材料和方法：对20例鼻咽癌放疗患者进行了VMAT（2弧）和IMRT（7-9野）的剂量学比较。靶区接受三个剂量水平（70，60和54戈伊），33分次使用同步积分加强技术。采用Philips Pinnacle计划系统9.0设计VMAT，使用SmartArc作为计划算法。为了进行公平比较，3个计划的规划目标体积（PTV）覆盖范围被标准化为相同水平。结果：VMAT、HT和IMRT计划的PTV覆盖率平均为96%。VMAT和HT的均匀性指数无显著性差异，但VMAT和HT的均匀性指数分别为1.06和1.06，均优于IMRT计划的均匀性指数（1.07，p < 0.05）。HT计划的符合性指数（1.17）优于VMAT（1.28，p = 0.01）和IMRT（1.36，p = 0.02）。与IMRT相比，VMAT和HT对脑干和脊髓的保护效果更好（p < 0.05）。VMAT（平均26.3戈伊）和HT（平均27.5戈伊）的腮腺保留效果相似，但优于IMRT（平均31.3戈伊，p < 0.01）。VMAT的每部分输送时间（5.7 min）远低于HT（9.5 min，p < 0.01）和IMRT（9.2 min，p < 0.01）。结论：我们的结果表明，VMAT比IMRT提供了更好的正常组织保留、均匀性和一致性，并且比HT输送时间更短。(C)2011爱思唯尔爱尔兰有限公司保留所有权利。放射治疗和肿瘤学104（2012）324-330
Purpose: Volumetric modulated arc therapy (VMAT), a novel technique, employs a linear accelerator to conduct dynamic modulation rotation radiotherapy. The goal of this study was to compare VMAT with helical tomotherapy (HT) and step-and-shoot intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) patients with regard to the sparing effect on organs at risk (OARs), dosimetric quality, and efficiency of delivery.Materials and methods: Twenty patients with NPC treated by HT were re-planned by VMAT (two arcs) and IMRT (7-9 fields) for dosimetric comparison. The target area received three dose levels (70, 60, and 54 Gy) in 33 fractions using simultaneous integrated boosts technique. The Philips Pinnacle Planning System 9.0 was adopted to design VMAT, using SmartArc as the planning algorithm. For a fair comparison, the planning target volume (PTV) coverage of the 3 plans was normalized to the same level. Dosimetric comparisons between VMAT, HT, and IMRT plans were analyzed to evaluate (1) coverage, homogeneity, and conformity of PTV, (2) sparing of OARs, (3) delivery time, and (4) monitor units (MUs).Results: The VMAT, HT, and IMRT plans had similar PTV coverage with an average of 96%. There was no significant difference between VMAT and HT in homogeneity, while the homogeneity indices of VMAT (1.06) and HT (1.06) were better than IMRT plans (1.07, p < 0.05). HT plans provided a better conformity index (1.17) than VMAT (1.28, p = 0.01) and IMRT (1.36, p = 0.02). When compared with IMRT, VMAT and HT had a better sparing effect on brain stem and spinal cord (p < 0.05). The effect of parotid sparing was similar between VMAT (mean = 26.3 Gy) and HT (mean = 27.5 Gy), but better than IMRT (mean = 31.3 Gy, p < 0.01). The delivery time per fraction for VMAT (5.7 min) were much lower than for HT (9.5 min, p < 0.01) and IMRT (9.2 min, p < 0.01).Conclusions: Our results indicate that VMAT provides better sparing of normal tissue, homogeneity, and conformity than IMRT, and shorter delivery time than HT. (C) 2011 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 104 (2012) 324-330