蒙特卡罗研究在光子束中塑料闪烁探测器的响应的能量和角度依赖性。

Monte Carlo study of the energy and angular dependence of the response of plastic scintillation detectors in photon beams.

机构信息

Department of Radiation Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.

出版信息

Med Phys. 2010 Oct;37(10):5279-86. doi: 10.1118/1.3488904.

DOI:10.1118/1.3488904

PMID:21089762

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC2951997/

Abstract

PURPOSE

By using Monte Carlo simulations, the authors investigated the energy and angular dependence of the response of plastic scintillation detectors (PSDs) in photon beams.

METHODS

Three PSDs were modeled in this study: A plastic scintillator (BC-400) and a scintillating fiber (BCF-12), both attached by a plastic-core optical fiber stem, and a plastic scintillator (BC-400) attached by an air-core optical fiber stem with a silica tube coated with silver. The authors then calculated, with low statistical uncertainty, the energy and angular dependences of the PSDs' responses in a water phantom. For energy dependence, the response of the detectors is calculated as the detector dose per unit water dose. The perturbation caused by the optical fiber stem connected to the PSD to guide the optical light to a photodetector was studied in simulations using different optical fiber materials.

RESULTS

For the energy dependence of the PSDs in photon beams, the PSDs with plastic-core fiber have excellent energy independence within about 0.5% at photon energies ranging from 300 keV (monoenergetic) to 18 MV (linac beam). The PSD with an air-core optical fiber with a silica tube also has good energy independence within 1% in the same photon energy range. For the angular dependence, the relative response of all the three modeled PSDs is within 2% for all the angles in a 6 MV photon beam. This is also true in a 300 keV monoenergetic photon beam for PSDs with plastic-core fiber. For the PSD with an air-core fiber with a silica tube in the 300 keV beam, the relative response varies within 1% for most of the angles, except in the case when the fiber stem is pointing right to the radiation source in which case the PSD may over-response by more than 10%.

CONCLUSIONS

At +/- 1% level, no beam energy correction is necessary for the response of all three PSDs modeled in this study in the photon energy ranges from 200 keV (monoenergetic) to 18 MV (linac beam). The PSD would be even closer to water equivalent if there is a silica tube around the sensitive volume. The angular dependence of the response of the three PSDs in a 6 MV photon beam is not of concern at 2% level.

摘要

目的

通过蒙特卡罗模拟，作者研究了塑料闪烁探测器（PSD）在光子束中的响应的能量和角度依赖性。

方法

本研究中对三种 PSD 进行了建模：一个塑料闪烁体（BC-400）和一个闪烁纤维（BCF-12），都通过塑料芯光纤茎连接，以及一个塑料闪烁体（BC-400）通过带有涂有银的二氧化硅管的空气芯光纤茎连接。然后，作者通过低统计不确定性，计算了水模体中 PSD 响应的能量和角度依赖性。对于能量依赖性，探测器的响应被计算为探测器剂量与单位水剂量之比。通过使用不同的光纤材料，在模拟中研究了连接到 PSD 以将光学光引导到光电探测器的光纤茎引起的扰动。

结果

对于光子束中 PSD 的能量依赖性，在从 300keV（单能）到 18MV（直线加速器束）的光子能量范围内，具有塑料芯光纤的 PSD 具有出色的能量独立性，误差约为 0.5%。具有带有二氧化硅管的空气芯光纤的 PSD 在相同的光子能量范围内也具有 1%以内的良好能量独立性。对于角度依赖性，所有三个建模的 PSD 的相对响应在 6MV 光子束的所有角度下都在 2%以内。对于具有塑料芯光纤的 PSD，在 300keV 单能光子束中也是如此。对于 300keV 束中的带有二氧化硅管的空气芯纤维的 PSD，除了光纤茎指向辐射源的情况外，相对响应在大多数角度下变化在 1%以内，在这种情况下，PSD 的响应可能会超过 10%。