Delivery efficiency of an Elekta linac under gated operation.
Delivery efficiency of an Elekta linac under gated operation.
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DOI：
10.1120/jacmp.v15i5.4713
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发表时间：
2014-09-08
影响因子：
2.1
通讯作者：
Shepard DM
中科院分区：
文献类型：
--
作者：
Cui G;Housley DJ;Chen F;Mehta VK;Shepard DM
在这项研究中，我们已经表征了Elekta直线加速器在提供门控放射治疗方面的效率。我们探索了减少束流延迟和提高投射效率的技术，并研究了频繁的束流中断对门控投射剂量测量精度的影响。在Elekta Synergy上安装了一个新的可用的门控接口。门控信号是使用结合呼吸运动体模的表面标测系统产生的。采用先前为接受立体定向全身放射治疗的肺癌患者制定的容量调节弧形疗法(VMAT)治疗计划，进行了一系列门控分娩。确定了交付时间的基线值。然后对机器进行了调整，以努力将束上延迟降至最低，并提高交付效率。在这一过程完成后，通过使用伽马指数分析比较测量的和计划的日冕剂量分布来评估门控投射的剂量学准确性。还进行了门控和非门控分娩的比较。结果表明，在优化的机器设置下，平均入射延迟降低到0.22 S以下，所有试验(3%/3 mm标准)的伽马指数通过率均不低于99.0%，具有较高的剂量测量精度。因此，Elekta直线加速器可以为门控VMAT治疗提供实用的解决方案，具有高剂量测量精度和仅适度增加总交付时间的特点。PAC编号：87.56.bd、87.55.de、87.55.ne
In this study, we have characterized the efficiency of an Elekta linac in the delivery of gated radiotherapy. We have explored techniques to reduce the beam‐on delay and to improve the delivery efficiency, and have investigated the impact of frequent beam interruptions on the dosimetric accuracy of gated deliveries. A newly available gating interface was installed on an Elekta Synergy. Gating signals were generated using a surface mapping system in conjunction with a respiratory motion phantom. A series of gated deliveries were performed using volumetric modulated arc therapy (VMAT) treatment plans previously generated for lung cancer patients treated with stereotactic body radiotherapy. Baseline values were determined for the delivery times. The machine was then tuned in an effort to minimize beam‐on delays and improve delivery efficiency. After that process was completed, the dosimetric accuracy of the gated deliveries was evaluated by comparing the measured and the planned coronal dose distributions using gamma index analyses. Comparison of the gated and the non‐gated deliveries were also performed. The results demonstrated that, with the optimal machine settings, the average beam‐on delay was reduced to less than 0.22 s. High dosimetric accuracy was demonstrated with gamma index passing rates no lower than 99.0% for all tests (3%/3 mm criteria). Consequently, Elekta linacs can provide a practical solution for gated VMAT treatments with high dosimetric accuracy and only a moderate increase in the overall delivery time. PACS numbers: 87.56.bd, 87.55.de, 87.55.ne