Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, United States of America. Author to whom any correspondence should be addressed.
Phys Med Biol. 2018 Apr 5;63(8):085001. doi: 10.1088/1361-6560/aab56c.
The purpose of this work was to characterize intensity and spectral response changes in a plastic scintillation detector (PSD) as a function of magnetic field strength. Spectra measurements as a function of magnetic field strength were performed using an optical spectrometer. The response of both a PSD and PMMA fiber were investigated to isolate the changes in response from the scintillator and the noise signal as a function of magnetic field strength. All irradiations were performed in water at a photon beam energy of 6 MV. Magnetic field strengths of (0, ±0.35, ±0.70, ±1.05, and ±1.40) T were investigated. Four noise subtraction techniques were investigated to evaluate the impact on the resulting noise-subtracted scintillator response with magnetic field strength. The noise subtraction methods included direct spectral subtraction, the spectral method, and variants thereof. The PMMA fiber exhibited changes in response of up to 50% with magnetic field strength due to the directional light emission from [Formula: see text]erenkov radiation. The PSD showed increases in response of up to 10% when not corrected for the noise signal, which agrees with previous investigations of scintillator response in magnetic fields. Decreases in the [Formula: see text]erenkov light ratio with negative field strength were observed with a maximum change at -1.40 T of 3.2% compared to 0 T. The change in the noise-subtracted PSD response as a function of magnetic field strength varied with the noise subtraction technique used. Even after noise subtraction, the PSD exhibited changes in response of up to 5.5% over the four noise subtraction methods investigated.
这项工作的目的是描述塑料闪烁探测器 (PSD) 的强度和光谱响应随磁场强度的变化。使用分光光度计进行了随磁场强度的光谱测量。研究了 PSD 和 PMMA 光纤的响应，以隔离响应随磁场强度的变化以及来自闪烁体和噪声信号的变化。所有辐照均在水介质中，光子束能量为 6MV。研究了 (0, ±0.35, ±0.70, ±1.05 和 ±1.40) T 的磁场强度。研究了四种噪声扣除技术，以评估它们对随磁场强度变化的噪声扣除后闪烁体响应的影响。噪声扣除方法包括直接光谱扣除、光谱方法及其变体。由于切伦科夫辐射的定向光发射，PMMA 光纤的响应随磁场强度的变化高达 50%。当不对噪声信号进行校正时，PSD 的响应增加高达 10%，这与先前对磁场中闪烁体响应的研究结果一致。随着负磁场强度的增加，切伦科夫光比减小，与 0T 相比，在最大负磁场强度 -1.40T 时最大变化为 3.2%。随磁场强度变化的噪声扣除后 PSD 响应的变化随所使用的噪声扣除技术而变化。即使在噪声扣除后，PSD 的响应变化仍高达 5.5%，这四种噪声扣除方法均如此。
