Back-irradiated and dual-screen sandwich detector configurations for radiography.
Back-irradiated and dual-screen sandwich detector configurations for radiography.
复制标题
用于射线照相的背照射和双屏夹层探测器配置。
DOI：
10.1117/1.jmi.6.3.033501
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Zhao,Wei
中科院分区：
文献类型：
--
作者：
Lubinsky,AnthonyR;Howansky,Adrian;Zheng,Hao;Zhao,Wei
薄膜晶体管阵列技术的最新进展使得“背面照射”（BI）间接有源矩阵平板成像仪（AMFPI）成为可能，其中X射线首先通过光学传感器暴露闪烁体，以及“双屏”AMFPI，其中两个闪烁屏夹在双向有源矩阵周围。我们开发了一个理论处理这样的探测器。该理论被用来调查可能的成像性能的改进，传统的“前照射”（FI）AMFPI，其中的有源矩阵是相对的X射线入射表面。调制传递函数、归一化噪声功率谱、Swank因子（As）、Lubberts函数L（f）和空间频率相关的量子探测效率DQE（f）的简单表达式 推导并用于计算各种FI、BI和双屏探测器配置的这些量。DQE（f） 用作优化和比较各种配置性能的品质因数。与FI单屏幕系统相比，BI的性能有了很大的提高。进一步的改进是可能的双屏配置。优化DQE的两个屏幕的厚度比通常是不对称的，其中较薄的屏幕面向入射通量。最佳比率取决于屏幕中的X射线衰减长度。
Recent advances in thin film transistor array technology have enabled the possibility of “back-irradiated” (BI) indirect active-matrix flat-panel imagers (AMFPIs), in which x-rays first expose the scintillator through the optical sensor, and “dual-screen” AMFPIs, in which two scintillating screens are sandwiched around a bidirectional active matrix. We developed a theoretical treatment of such detectors. The theory is used to investigate possible imaging performance improvements over conventional “front-irradiation” (FI) AMFPIs, where the active matrix is opposite the x-ray entrance surface. Simple expressions for the modulation transfer function, normalized noise power spectrum, Swank factor (As), Lubberts functionL(f) , and spatial frequency-dependent detective quantum efficiency DQE (f) are derived and used to compute these quantities for a variety of FI, BI, and dual-screen detector configurations. DQE (f) is used as the figure of merit for optimizing and comparing the performance of the various configurations. Large performance improvements over FI single-screen systems are found possible with BI. Further improvements are found possible with dual-screen configurations. The ratio of the thicknesses of the two screens that optimizes DQE is generally asymmetric, with the thinner screen facing the incident flux. The optimum ratio depends on the x-ray attenuation length in the screen.