Yi Jinling, Han Ce, Zheng Xiaomin, Zhou Yongqiang, Deng Zhenxiang, Xie Congying, Jin Xiance, Jin Fu
Department of Radiotherapy and Chemotherapy, The 1st Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
Physics Unit, Department of Radiation Oncology, Chongqing Cancer Hospital & Institute, Chongqing, China.
J Appl Clin Med Phys. 2017 May;18(3):28-36. doi: 10.1002/acm2.12062. Epub 2017 Mar 20.
Although gamma analysis is still a widely accepted quantitative tool to analyze and report patient-specific QA for intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT), the correlation between the 2D percentage gamma passing rate (%GP), and the clinical dosimetric difference for IMRT and VMAT has been questioned. The purpose of this study was to investigate the feasibility of individual volume-based 3D gamma indices for pretreatment VMAT QA. Percentage dosimetric errors (%DE) of dose-volume histogram metrics (includes target volumes and organ at risks) between the treatment planning system and QA-reconstructed dose distribution, %GPs for individual volume and global gamma indices, as well their correlations and sensitivities were investigated for one- and two-arc VMAT plans. The %GPs of individual volumes had a higher percent of correlation with individual 15 %DE metrics compared with global %GPs. For two-arc VMAT at 2%/2 mm, 3%/3 mm, and 4%/4 mm criteria, individual volume %GPs were correlated with 9, 12, and 9 out of 15 %DE metrics, while global %GPs were correlated with only 2 out of 15 %DE metrics, respectively. For one-arc VMAT at 2%/2 mm, 3%/3 mm, and 4%/4 mm criteria, individual volume %GPs were correlated with 18, 16, and 13 out of 23 %DE metrics, and global %GPs were correlated with 19, 12, and 1 out 23 %DE metrics, respectively. The area under curves (AUC) of individual volume %GPs were higher than those of global %GPs for two-arc VMAT plans, but with mixed results for one-arc VMAT plans. In a conclusion, the idea of individual volume %GP was created and investigated to better serve for VMAT QA and individual volume-based %GP had a higher percent of correlation with DVH 15 %DE metrics compared with global %GP for both one- and two-arc VMAT plans.
尽管伽马分析仍是分析和报告调强放射治疗（IMRT）和容积调强弧形治疗（VMAT）患者特定质量保证（QA）的广泛接受的定量工具，但二维伽马通过率（%GP）与IMRT和VMAT临床剂量学差异之间的相关性受到质疑。本研究的目的是探讨基于个体体积的三维伽马指数用于VMAT治疗前QA的可行性。研究了治疗计划系统与QA重建剂量分布之间剂量体积直方图指标（包括靶区体积和危及器官）的剂量误差百分比（%DE）、个体体积和全局伽马指数的%GP，以及它们之间的相关性和敏感性，涉及单弧和双弧VMAT计划。与全局%GP相比，个体体积的%GP与个体15%DE指标的相关性百分比更高。对于双弧VMAT，在2%/2mm、3%/3mm和4%/4mm标准下，个体体积%GP分别与15个%DE指标中的9个、12个和9个相关，而全局%GP分别仅与15个%DE指标中的2个相关。对于单弧VMAT，在2%/2mm、3%/3mm和4%/4mm标准下，个体体积%GP分别与23个%DE指标中的18个、16个和13个相关，全局%GP分别与23个%DE指标中的19个、12个和1个相关。对于双弧VMAT计划，个体体积%GP的曲线下面积（AUC）高于全局%GP，但对于单弧VMAT计划结果不一。总之，提出并研究了个体体积%GP的概念，以更好地服务于VMAT QA，并且对于单弧和双弧VMAT计划，基于个体体积的%GP与DVH 15%DE指标的相关性百分比均高于全局%GP。
