Empirical and theoretical investigation of the noise performance of indirect detection, active matrix flat-panel imagers (AMFPIs) for diagnostic radiology
Empirical and theoretical investigation of the noise performance of indirect detection, active matrix flat-panel imagers (AMFPIs) for diagnostic radiology
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DOI：
10.1118/1.597919
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发表时间：
1997-01-01
期刊：
影响因子：
3.8
通讯作者：
Cunningham, IA
中科院分区：
文献类型：
--
作者：
Siewerdsen, JH;Antonuk, LE;Cunningham, IA
研究了有源矩阵平板成像器在放射诊断条件下的噪声特性。这些研究的重点是成像器的基础上的像素阵列，将一个分立的光电二极管耦合到薄膜晶体管，都从氢化非晶硅制造。这些光学敏感阵列与上覆的X射线转换器一起操作，以允许间接检测入射X射线。外部电子设备，包括栅极驱动器电路和前置放大电路，也需要操作阵列。一个理论模型描述的信号和噪声传输特性的成像相关的条件下，诊断X线摄影，荧光透视，和乳房X线摄影。该频率相关模型基于级联系统分析，其中成像器在概念上被划分为具有固有增益和扩展特性的一系列级。从该模型的预测进行比较，与X射线的灵敏度和噪声测量获得从个别像素的成像器与像素格式为1536 × 1920像素在像素间距为127 μ m。该模型被证明是在良好的协议与诊断X射线使用各种荧光屏获得的测量。该模型用于探索现有和假设成像器在X线摄影、荧光透视和乳腺X线摄影中的潜在性能，作为曝光、加性噪声和填充因子的函数。这些理论预测表明，结合CsI：TI增感屏的这种一般设计的成像器可以被优化，以提供比用于一般射线照相术和乳房X射线照相术的现有屏-膜和存储磷光体系统上级的探测量子效率（DQE）。对于荧光透视，该模型预测，随着a-Si：H成像器的进一步优化，DQE性能接近最好的X射线图像增强器系统是可能的。该分析的结果为该成像技术的未来改进提出了策略。(C)1997年美国医学物理学家协会。
Noise properties of active matrix, flat-panel imagers under conditions relevant to diagnostic radiology are investigated. These studies focus on imagers based upon arrays with pixels incorporating a discrete photodiode coupled to a thin-film transistor, both fabricated from hydrogenated amorphous silicon. These optically sensitive arrays are operated with an overlying x-ray converter to allow indirect detection of incident x rays. External electronics, including gate driver circuits and preamplification circuits, are also required to operate the arrays. A theoretical model describing the signal and noise transfer properties of the imagers under conditions relevant to diagnostic radiography, fluoroscopy, and mammography is developed. This frequency-dependent model is based upon a cascaded systems analysis wherein the imager is conceptually divided into a series of stages having intrinsic gain and spreading properties. Predictions from the model are compared with x-ray sensitivity and noise measurements obtained from individual pixels from an imager with a pixel format of 1536 x 1920 pixels at a pixel pitch of 127 mu m. The model is shown to be in excellent agreement with measurements obtained with diagnostic x rays using various phosphor screens. The model is used to explore the potential performance of existing and hypothetical imagers for application in radiography, fluoroscopy, and mammography as a function of exposure, additive noise, and fill factor. These theoretical predictions suggest that imagers of this general design incorporating a CsI:TI intensifying screen can be optimized to provide detective quantum efficiency (DQE) superior to existing screen-film and storage phosphor systems for general radiography and mammography. For fluoroscopy, the model predicts that with further optimization of a-Si:H imagers, DQE performance approaching that of the best x-ray image intensifier systems may be possible. The results of this analysis suggest strategies for future improvements of this imaging technology. (C) 1997 American Association of Physicists in Medicine.