Monte Carlo study of the energy and angular dependence of the response of plastic scintillation detectors in photon beams.
Monte Carlo study of the energy and angular dependence of the response of plastic scintillation detectors in photon beams.
复制标题
蒙特卡罗研究塑料闪烁探测器在光子束中的响应的能量和角度依赖性。
DOI：
10.1118/1.3488904
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发表时间：
2010
期刊：
影响因子：
3.8
通讯作者：
Beddar,ASam
中科院分区：
文献类型：
--
作者：
Wang,LilieLW;Klein,David;Beddar,ASam
用蒙特卡罗模拟方法研究了塑料闪烁探测器(PSD)在光子光束中的响应与能量和角度的关系。方法建立了三种PSD的模型：塑料闪烁体(BC-400)和闪烁光纤(BCF-12)，均由塑料芯光纤杆连接，塑料闪烁体(BC-400)由空芯光纤杆连接，石英管镀银。然后，作者以很低的统计不确定性计算了PSD在水模中的响应的能量和角度依赖关系。对于能量依赖，探测器的响应被计算为每单位水剂量的探测器剂量。结果在光子能量为300keV(单能)到18 mV(直线加速器光束)的范围内，塑料芯光纤PSD在约0.5%的能量范围内具有很好的能量独立性。在相同的光子能量范围内，具有空芯光纤和硅管的PSD在1%以内也具有良好的能量独立性。对于角度依赖关系，对于6 MV光子束中的所有角度，三种建模的PSD的相对响应度都在2%以内。对于带塑料芯光纤的PSD，300keV的单能光子束也是如此。对于300keV束流中带有石英管空芯光纤的PSD，除了光纤杆指向辐射源的情况外，大部分角度的相对响应都在1%以内，此时PSD可能会过度响应10%以上。结论在±1%的水平上，在200keV(单能)到18 mV(直线加速器束)的光子能量范围内，不需要对所模拟的三种PSD的响应进行束流能量校正。如果在敏感体积周围有一根硅管，PSD将更接近于水当量。在2%的水平上，3个PSD在6 mV光子束中的响应与角度的关系不受关注。
PurposeBy using Monte Carlo simulations, the authors investigated the energy and angular dependence of the response of plastic scintillation detectors (PSDs) in photon beams.MethodsThree 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.ResultsFor 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%.ConclusionsAt ±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.