作者：赖佳路, 马超琼, 勾成俊, 吴章文, 侯氢

作者单位：四川大学原子核科学技术研究所 辐射物理及技术教育部重点实验室, 四川 成都 610064

关键词：容积旋转调强;角度间隔;等中心;剂量分布;剂量评估

摘要：

针对容积旋转调强放疗计划系统的剂量精度验证问题,考察剂量计算中照射弧的离散化处理对剂量验证的影响。通过改变模拟射野随机架角的变化关系并结合因子分析,结果表明:当射野形状随机架角变化缓慢时,增大离散间隔,主要对低剂量区的剂量分布有明显影响,90%剂量检验通过率容易达到;当射野形状随机架角变化快时,增大离散间隔对低剂量和高剂量区的剂量分布都有明显影响,剂量检验通过率明显降低,此时照射弧的离散化角度间隔应不大于4,才能获得较满意的剂量检验通过率。另外,剂量检验通过率与模体几何和旋转调强的等中心位置的选取没有明显的依赖性。

Influence of VMAT's field angle clearance on dose verification

LAI Jialu, MA Chaoqiong, GOU Chengjun, WU Zhangwen, HOU Qing

Key Lab of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China

Abstract: The influence of discretization treatment of irradiation arc in the dose calculation is inspected in allusion to the problem on verification of dose precision in the radiation treatment planning system of volumetric modulated arc therapy(VMAT). By changing the variable relationship of simulated field along with the gantry angle and combining with factor analysis, it discovers that when the variation of the field shape is moderate, the discretization clearance is enlarged, which has obvious influence on low-dosage area mainly, and passing rate of dose verification is easy to reach 90%. When the variation of the field shape is fast along with the gantry angle, enlargement of discretization clearance has obvious influence on both the low-dose and high-dose areas, and passing rate of dose verification is reduced obviously. Under such circumstances, discretization angle clearance of irradiation arc shall not be greater than 4°, and then satisfied passing rate of dose verification can be acquired. In addition, passing rate of dose verification weakly depends on the phantom geometry and the VMAT isocenter location.

Keywords: VMAT;angle clearance;isocenter;dose distributions;dose evaluation

2016, 42(6): 23-28  收稿日期: 2015-10-20;收到修改稿日期: 2015-12-09

基金项目: 

作者简介: 赖佳路(1989-),男,四川眉山市人,硕士研究生,专业方向为辐射物理与医学物理。

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