Imaging Cherenkov emission for quality assurance of high-dose-rate brachytherapy
Imaging Cherenkov emission for quality assurance of high-dose-rate brachytherapy
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DOI：
10.1038/s41598-020-60519-z
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发表时间：
2020-02-27
影响因子：
4.6
通讯作者：
Hayakawa, Kazushige
中科院分区：
文献类型：
--
作者：
Yogo, Katsunori;Matsushita, Akihiro;Hayakawa, Kazushige
随着高剂量率（HDR）近距离放射治疗的发展，质量保证（QA）的重要性越来越大，以确保安全的治疗，通过测量剂量分布和定位源与更紧密的间隔高活性源。然而，传统的QA是耗时的，涉及到使用几种不同的测量工具。在这里，我们开发了简单的QA方法的HDR近距离放射治疗的基础上成像的切伦科夫发射，并评估其性能。使用电荷耦合器件照相机捕获由Ir-192伽马射线源照射的纯水的光发射。蒙特卡罗计算表明，观测到的光主要是由伽马射线的康普顿散射电子产生的切伦科夫辐射。未校正的切伦科夫光分布（除靠近光源（距中心7 mm内）外，平均为5%）与使用治疗计划系统计算的剂量分布一致。准确性归因于各向同性辐射和短程康普顿电子。从光图像测量的源位置间隔与预期的间隔相当，产生的空间分辨率与常规胶片测量所允许的空间分辨率相似。该方法应该是非常适合的快速和简单的QA调查的HDR近距离放射治疗，因为它允许同时测量的剂量分布，源强度和源位置使用一个单一的图像。
With advances in high-dose-rate (HDR) brachytherapy, the importance of quality assurance (QA) is increasing to ensure safe delivery of the treatment by measuring dose distribution and positioning the source with much closer intervals for highly active sources. However, conventional QA is time-consuming, involving the use of several different measurement tools. Here, we developed simple QA method for HDR brachytherapy based on the imaging of Cherenkov emission and evaluated its performance. Light emission from pure water irradiated by an Ir-192 gamma-ray source was captured using a charge-coupled device camera. Monte Carlo calculations showed that the observed light was primarily Cherenkov emissions produced by Compton-scattered electrons from the gamma-rays. The uncorrected Cherenkov light distribution, which was 5% on average except near the source (within 7 mm from the centre), agreed with the dose distribution calculated using the treatment planning system. The accuracy was attributed to isotropic radiation and short-range Compton electrons. The source positional interval, as measured from the light images, was comparable to the expected intervals, yielding spatial resolution similar to that permitted by conventional film measurements. The method should be highly suitable for quick and easy QA investigations of HDR brachytherapy as it allows simultaneous measurements of dose distribution, source strength, and source position using a single image.