Dosimetric analysis of isocentrically shielded volumetric modulated arc therapy for locally recurrent nasopharyngeal cancer.
Dosimetric analysis of isocentrically shielded volumetric modulated arc therapy for locally recurrent nasopharyngeal cancer.
复制标题
局部复发鼻咽癌等中心屏蔽体积调制弧疗法的剂量分析。
DOI：
10.1038/srep25959
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发表时间：
2016-05-13
影响因子：
4.6
通讯作者：
Li M
中科院分区：
文献类型：
--
作者：
Lu JY;Huang BT;Xing L;Chang DT;Peng X;Xie LX;Lin ZX;Li M
本研究旨在探讨等中心屏蔽RapidArc（IS-RA）技术治疗局部复发鼻咽癌（lrNPC）的剂量学特征。在IS-RA中，将等中心点放置在预辐照脑干（BS）/脊髓（SC）的中心，并将钳口设置为屏蔽BS/SC，同时确保整个机架旋转期间的目标覆盖。对于15例患者，比较了IS-RA计划与传统RapidArc（C-RA）的靶覆盖率、危及器官（OAR）保留率和监测单位（MU）。分析靶点与BS/SC轴的夹角（Ang_BSSC）、靶点与BS/SC的最小距离（Dist_Min）、靶点体积等几何参数与BS/SC剂量降低的关系。与C-RA相比，IS-RA平均将BS/SC剂量减少约1-4戈伊，MU更多。IS-RA表现出与其他OAR相似的靶区覆盖和保留，除了光学结构的保留略有改善。更多的剂量减少在等中心区域的情况下，观察到较大的Ang_BSSC或较小的Dist_Min。我们的研究结果表明，IS-RA显着提高了节约BS/SC不影响剂量测定要求的其他相关结构的lrNPC。
This study aimed to investigate the dosimetric characteristics of an isocentrically shielded RapidArc (IS-RA) technique for treatment of locally recurrent nasopharyngeal cancer (lrNPC). In IS-RA, the isocenter was placed at the center of the pre-irradiated brainstem (BS)/spinal cord (SC) and the jaws were set to shield the BS/SC while ensuring the target coverage during the whole gantry rotation. For fifteen patients, the IS-RA plans were compared with the conventional RapidArc (C-RA) regarding target coverage, organ-at-risk (OAR) sparing and monitor units (MUs). The relationship between the dose reduction of BS/SC and some geometric parameters including the angle extended by the target with respect to the axis of BS/SC (Ang_BSSC), the minimum distance between the target and BS/SC (Dist_Min) and the target volume were evaluated. The IS-RA reduced the BS/SC doses by approximately 1–4 Gy on average over the C-RA, with more MUs. The IS-RA demonstrated similar target coverage and sparing of other OARs except for slightly improved sparing of optic structures. More dose reduction in the isocentric region was observed in the cases with larger Ang_BSSC or smaller Dist_Min. Our results indicated that the IS-RA significantly improves the sparing of BS/SC without compromising dosimetric requirements of other involved structures for lrNPC.