Quality assurance in proton beam therapy using a plastic scintillator and a commercially available digital camera
Quality assurance in proton beam therapy using a plastic scintillator and a commercially available digital camera
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DOI：
10.1002/acm2.12143
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发表时间：
2017-09-01
影响因子：
2.1
通讯作者：
Gibson, Adam
中科院分区：
文献类型：
--
作者：
Almurayshid, Mansour;Helo, Yusuf;Gibson, Adam
目的：在这篇文章中，我们评估了塑料闪烁探测器系统的质量保证质子治疗使用BC-408塑料闪烁体，商业相机，和computer.Methods：该系统的基本特性进行了评估，在一系列的质子辐照。测定了重复性和对剂量、剂量率和质子能量变化的响应。获得闪烁光分布的照片，并与Geant 4 Monte Carlo模拟和电离室测量的深度-剂量曲线进行比较。在60 MeV质子束的布拉格峰处观察到淬灭效应，其中产生的光比预期的少。我们开发了一种方法，使用Birks方程来校正这种猝灭。我们在Geant 4中模拟了线性能量传递（LET）随深度的变化，并通过比较计算的LET和测量的闪烁光分布发现了Birks常数。结果：校正后的闪烁体光输出与剂量成线性关系。该系统稳定，短期重现性在0.80%以内。结论：该方法提供了一种有效的校正淬灭的方法，为临床质子束的质量保证提供了一种快速、方便、常规的方法。此外，该系统具有提供单个辐射场的2D可视化的优点，具有复杂的时变场的质量保证的潜在应用。
Purpose: In this article, we evaluate a plastic scintillation detector system for quality assurance in proton therapy using a BC-408 plastic scintillator, a commercial camera, and a computer.Methods: The basic characteristics of the system were assessed in a series of proton irradiations. The reproducibility and response to changes of dose, dose-rate, and proton energy were determined. Photographs of the scintillation light distributions were acquired, and compared with Geant4 Monte Carlo simulations and with depth-dose curves measured with an ionization chamber. A quenching effect was observed at the Bragg peak of the 60 MeV proton beam where less light was produced than expected. We developed an approach using Birks equation to correct for this quenching. We simulated the linear energy transfer ( LET) as a function of depth in Geant4 and found Birks constant by comparing the calculated LET and measured scintillation light distribution. We then used the derived value of Birks constant to correct the measured scintillation light distribution for quenching using Geant4.Results: The corrected light output from the scintillator increased linearly with dose. The system is stable and offers short-term reproducibility to within 0.80%. No dose rate dependency was observed in this work.Conclusions: This approach offers an effective way to correct for quenching, and could provide a method for rapid, convenient, routine quality assurance for clinical proton beams. Furthermore, the system has the advantage of providing 2D visualization of individual radiation fields, with potential application for quality assurance of complex, time-varying fields.