Direct measurement of Lubberts effect in CsI:Tl scintillators using single x-ray photon imaging
Direct measurement of Lubberts effect in CsI:Tl scintillators using single x-ray photon imaging
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使用单 X 射线光子成像直接测量 CsI:Tl 闪烁体中的鲁伯特效应
DOI：
10.1117/12.2255561
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发表时间：
2017
影响因子：
--
通讯作者：
Wei Zhao
中科院分区：
文献类型：
--
作者：
A. Howansky;A. Lubinsky;S. Ghose;Katsuhiko Suzuki;Wei Zhao
间接平板探测器(I-FPD)的成像性能从根本上受到其闪烁体的限制。闪烁体的调制传递函数(MTF)作为层中X射线相互作用的深度的函数而变化，这是由于在被光学传感器检测之前光的横向扩散的不同。这种变化降低了I-FPD的空间频率相关的探测量子效率(DQE(F))，并被Lubberts效应量化。已经用蒙特卡罗模拟估算了用于I-FPD的各种闪烁体随深度变化的MTF，但从来没有直接测量过。本文首次实验测量了厚度在200-1000μm范围内的掺Tl碘化铯(CsI)和掺Tb的Gd2O2S(GOS)闪烁体的调制传递函数随深度的变化。利用平行同步辐射(32keV)的微缝光束定位闪烁体中的X射线相互作用深度，并在50±1微米深度间隔内通过平移来改变深度。利用成像光爆发的傅里叶分析推导出MTF与X射线相互作用深度z的关系，并用MTF(z，f)的测量结果计算了RQA-M3、RQA5和RQA9光束质量下的预采样MTF(F)，并与传统的斜边测量结果进行了比较。深度变化的光爆发的图像被用来推导出32keV光束的每个闪烁体的Lubberts函数。
The imaging performance of an indirect flat panel detector (I-FPD) is fundamentally limited by that of its scintillator. The scintillator’s modulation transfer function (MTF) varies as a function of the depth of x-ray interaction in the layer, due to differences in the lateral spread of light before detection by the optical sensor. This variation degrades the spatial frequency-dependent detective quantum efficiency (DQE(f)) of I-FPDs, and is quantified by the Lubberts effect. The depth-dependent MTFs of various scintillators used in I-FPDs have been estimated using Monte Carlo simulations, but have never been measured directly. This work presents the first experimental measurements of the depth-dependent MTF of thallium-doped cesium iodide (CsI) and terbium-doped Gd2O2S (GOS) scintillators with thickness ranging from 200 – 1000 μm. Light bursts from individual x-ray interactions occurring at known, fixed depths within a scintillator are imaged using an ultra-high-sensitivity II-EMCCD (image-intensifier, electron multiplying charge coupled device) camera. X-ray interaction depth in the scintillator is localized using a micro-slit beam of parallel synchrotron radiation (32 keV), and varied by translation in 50 ± 1 µm depth intervals. Fourier analysis of the imaged light bursts is used to deduce the MTF versus x-ray interaction depth z. Measurements of MTF(z,f) are used to calculate presampling MTF(f) with RQA-M3, RQA5 and RQA9 beam qualities and compared with conventional slanted edge measurements. Images of the depth-varying light bursts are used to derive each scintillator’s Lubberts function for a 32 keV beam.
影响因子：
3.8
作者：
Star-Lack, Josh;Sun, Mingshan;Abel, Eric
通讯作者：
Abel, Eric
影响因子：
3.8
作者：
Zhao, W;Ristic, G;Rowlands, JA
通讯作者：
Rowlands, JA