Identical Quality Assurance for Volumetric Modulated Arc Therapy in Elekta and Varian Machines
Identical Quality Assurance for Volumetric Modulated Arc Therapy in Elekta and Varian Machines
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DOI：
10.1177/1533034614500419
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发表时间：
2015-08-01
影响因子：
2.8
通讯作者：
Zhang, Zhen
中科院分区：
文献类型：
--
作者：
Wang, Jiazhou;Hu, Weigang;Zhang, Zhen
体积调强弧形放射治疗（VMAT）由于其比常规调强放射治疗技术更高的治疗效率而被许多临床所采用。目前，质量保证（QA）仍然是一个挑战，因为不同供应商的加速器没有相同的测试。本研究是首次尝试为瓦里安和Elekta机器的VMAT技术设计相同的QA测试。为两台机器创建了测试MLC位置和移动、剂量率变化以及机架位置和移动的相同程序。这些测试包括尖桩栅栏（PF）、剂量率与机架速度（DRGS）和MLC速度与剂量率（MLCDR）测试。这些测试的可行计划是用内部软件制定的，该软件可用于两家供应商（Elekta Synergy和Varian Trilogy）的直线加速器。电子射野成像设备（EPID）用于这些测试。建立了自动化分析方法，并创建了软件来定量评价结果。PF测试的系统间隙位置和宽度误差在0.5 mm以内。我们评估了该程序的可检测性，引入的误差下降到0.2 mm。引入的误差和测量误差之间存在线性关系。在DRGS测试中，对于Synergy和Trilogy，99.8%和100.0%的强度与预期曲线的偏差分别小于3%。对于MLCDR，Synergy和Trilogy的强度与预期曲线的偏差小于3%，分别为100.0%和98.1%。为两家供应商的VMAT加速器创建并实施了相同的测试系列。报告了两种加速器的试验结果。从两个供应商处获得了可比较的结果，从而能够为VMAT质量保证建立统一的标准。
Volumetric modulated arc therapy (VMAT) has been adopted by many clinics for its higher delivery efficiency compared to conventional intensity modulated radiotherapy techniques. Currently, the quality assurance (QA) has remained a challenge in that no identical tests are available for accelerators from different vendors. This study is the first attempt to design identical QA tests for the VMAT technique for Varian and Elekta machines. Identical procedures testing MLC positions and movements, dose rate variations, and gantry positions and movement were created for both machines. These included picket fence (PF), dose rate vs. gantry speed (DRGS) and MLC speed vs. dose rate (MLCDR) tests. Deliverable plans for these tests were made with in-house software that was deliverable for linacs from two vendors (Elekta Synergy and Varian Trilogy). The electronic portal imaging device (EPID) was used for these tests. An automated analysis method was established and software was created to quantitatively evaluate the result. The systematic gap position and width errors from PF tests were within 0.5 mm. We evaluated the detectability of this program for introduced errors down to 0.2 mm. Linear relationships existed between the introduced errors and measured errors. In the DRGS test, 99.8% and 100.0% of the intensity deviations from expected profiles were less than 3% for the Synergy and Trilogy, respectively. For the MLCDR, the intensity deviations from expected profiles less than 3% were 100.0% for Synergy and 98.1% for Trilogy. Identical test series were created and implemented for VMAT accelerators from two vendors. Test results were reported from both accelerators. Comparable results were obtained from both vendors, enabling uniform criteria to be established for VMAT quality assurance.