The ionization quenching phenomenon in scintillators must be corrected to obtain accurate dosimetry in particle therapy. The purpose of this study was to develop a methodology for correcting camera projection measurements of a 3D scintillator detector exposed to proton pencil beams. Birks' ionization quenching model and the energy deposition by secondary electrons (EDSE) model were used to correct the light captured by a prototype 3D scintillator detector. The detector was made of a 20 cm  20 cm  20 cm tank filled with liquid scintillator, and three cameras. The detector was exposed to four proton-beam energies (84.6, 100.9, 144.9, and 161.6 MeV) at The University of Texas MD Anderson Cancer Center's Proton Therapy Center. The dose and track averaged linear energy transfer (LET) were obtained using validated Monte Carlo (MC) simulations. The corrected light output was compared to the dose calculated by the MC simulation. Optical artefact corrections were used to correct for refraction at the air-scintillator interface, and image perspective. These corrections did not account for the non-orthogonal integration of data off the central axis of the image. Therefore, we compared the light output to an integrated MC dose and LET along the non-orthogonal path. After accounting for the non-orthogonal integration of the data, the corrected light output reduced the dose error at the Bragg peak region from 15% to 3% for low proton-beam energies. Overall, the doses at the Bragg peak region using the Birks' model and EDSE model were less than ±3% and ±7% of the MC dose, respectively. We have improved the application of Birks' model quenching corrections in 3D scintillators by numerically projecting the dose and LET 3D grid to camera projections. This study shows that scintillator projections can be corrected using average LET values at the central axes.

中文翻译：

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暴露于扫描质子束的3D闪烁体探测器的电离猝灭校正。

必须纠正闪烁体中的电离猝灭现象，以便在粒子治疗中获得准确的剂量。这项研究的目的是开发一种校正暴露于质子铅笔束的3D闪烁体探测器的相机投影测量方法。Birks的电离猝灭模型和二次电子的能量沉积（EDSE）模型用于校正原型3D闪烁探测器检测到的光。检测器由一个装有液体闪烁器的20 cm×20 cm×20 cm的水箱和三个摄像头组成。在德克萨斯大学MD安德森癌症中心的质子治疗中心，检测器暴露于四种质子束能量（84.6、100.9、144.9和161.6 MeV）。使用经过验证的蒙特卡洛（MC）模拟获得剂量和轨道平均线性能量转移（LET）。将校正后的光输出与通过MC模拟计算的剂量进行比较。光学伪影校正用于校正空气闪烁器界面和图像透视的折射。这些校正不考虑偏离图像中心轴的数据的非正交积分。因此，我们将光输出与沿非正交路径的积分MC剂量和LET进行了比较。在考虑了数据的非正交积分之后，对于低质子束能量，校正后的光输出将布拉格峰区域的剂量误差从15％降低到3％。总体而言，使用Birks模型和EDSE模型在布拉格峰区域的剂量分别小于MC剂量的±3％和±7％。我们改进了Birks' 通过将剂量和LET 3D网格数值投影到相机投影中，对3D闪烁体中的猝灭校正进行建模。这项研究表明，可以使用中心轴上的平均LET值来校正闪烁体的投影。