Evaluation of a hybrid direct-indirect active matrix flat-panel imager using Monte Carlo simulation.
Evaluation of a hybrid direct-indirect active matrix flat-panel imager using Monte Carlo simulation.
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使用蒙特卡罗模拟评估混合直接-间接有源矩阵平板成像仪。
DOI：
10.1117/1.jmi.7.3.033501
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Zhao,Wei
中科院分区：
文献类型：
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作者：
Dow,Scott;Howansky,Adrian;Lubinsky,AnthonyR;Zhao,Wei
目的：蒙特卡罗模拟用于评估复合直接-间接有源矩阵平板成像仪（AMFPI）的成像特性，与单独的直接或间接AMFPI相比，AMFPI在X射线量子效率和空间分辨率之间具有潜在更有利的权衡。这种配置，称为混合AMFPI，包括闪烁体，其通过透明电极和空穴阻挡层光学耦合到a-Se直接AMFPI，使得a-Se充当直接X射线转换器和光学传感器。方法：GEANT 4用于模拟在RQA 5和RQA 9 X射线束条件下各种混合AMFPI配置中的X射线能量沉积、光学传输和电荷信号生成过程。Fujita-Lubberts-Swank方法用于量化照射几何形状、X射线转换器厚度、每层的转换增益和层间X射线串扰对探测量子效率（DQE）的影响。由于闪烁体提供的X射线量子效率增加，DQE改善在前照射和后照射（BI）几何形状中的低空间频率下最大。由于a-Se中的优先X射线吸收，DQE改善在BI几何结构中的较高频率下持续存在。匹配混合AMFPI的直接和间接检测层的X射线到电荷转换增益会影响其Swank因子，从而影响DQE（0）。X射线串扰对DQE（f）的影响可忽略不计 结论：优化后的混合AMFPI比现有的直接或间接AMFPI具有更好的DQE性能。
Purpose:Monte Carlo simulations were used to evaluate the imaging properties of a composite direct–indirect active matrix flat-panel imager (AMFPI) with potentially more favorable tradeoffs between x-ray quantum efficiency and spatial resolution than direct or indirect AMFPIs alone. This configuration, referred to as a hybrid AMFPI, comprises a scintillator that is optically coupled to an a-Se direct AMFPI through a transparent electrode and hole blocking layer, such that a-Se acts as both a direct x-ray converter and an optical sensor.Approach:GEANT4 was used to simulate x-ray energy deposition, optical transport, and charge signal generation processes in various hybrid AMPFI configurations under RQA5 and RQA9 x-ray beam conditions. The Fujita–Lubberts–Swank method was used to quantify the impact of irradiation geometry, x-ray converter thicknesses, conversion gain of each layer, and x-ray cross talk between layers on detective quantum efficiency (DQE).Results:Each hybrid configuration had a greater DQE than its direct AMFPI layer alone. The DQE improvement was largest at low spatial frequencies in both front- and back-irradiation (BI) geometries due to increased x-ray quantum efficiency provided by the scintillator. DQE improvements persisted at higher frequencies in BI geometry due to preferential x-ray absorption in a-Se. Matching the x-ray-to-charge conversion gains of a hybrid AMFPI’s direct and indirect detection layers affects its Swank factor and, thus, DQE(0). X-ray cross talk has a negligible impact on the DQE (f) of hybrid AMFPIs with sufficiently high optical quantum efficiency.Conclusion:An optimized hybrid AMFPI can achieve greater DQE performance than current direct or indirect AMFPIs.