Modeling and characterization of imaging detectors for diagnostic medical digital imaging

基于X射线检测介质（光电导体或磷光体）的平板数字X射线图像传感器具有自扫描有源矩阵阵列，可提供出色的X射线图像。这些图像传感器以电子方式捕获X射线图像，因此通过取代传统的基于胶片的系统，实现了向数字X射线照相术的临床过渡。从临床角度来看，数字成像具有巨大的意义。 它们不仅使医生能够更快地检索和检查图像，而且具有高度便携性，可以由非现场专家进行分析。X射线探测器现在可用于普通X射线照相术和乳房X射线照相术，并且正在考虑用于荧光透视。然而，仍然存在与暗电流、图像滞后和重影、电子噪声、X射线诱导效应和探测器的长期稳定性相关的重大科学挑战。因此，有许多基础性的工作要做，以提高探测器的性能。拟议的研究的目标是通过探测器建模和表征任务，确定引起暗电流，瞬态光响应，雪崩增益和噪声，X射线引起的探测器灵敏度（重影）和图像探测器分辨率变化的物理机制。本研究的第二个目的是研究X射线光电导体的材料特性。

Flat-panel digital X-ray image sensors based on an X-ray detecting medium (either a photoconductor or a phosphor) with a self-scanned active matrix arrays provide excellent X-ray images. These image sensors capture an X-ray image electronically, and hence enable a clinical transition to digital radiography by replacing the traditional film based system. Digital imaging has tremendous implications from a clinical standpoint. Not only do they allow doctors to retrieve and inspect images quicker, they are highly portable and can be analyzed by specialists who are off-site. X-ray detectors are now commercially available for general radiography and mammography, and are under consideration for use in fluoroscopy. However, there still remain significant scientific challenges associated with dark current, image lag and ghosting, electronic noises, X-ray induced effects and long term stability of the detector. Therefore, there is much fundamental work to be done to enhance detector performance. The objectives of the proposed research are to determine the physical mechanisms causing dark current, transient photoresponse, avalanche gain and noise, X-ray induced change in detector sensitivity (ghosting) and resolution in image detectors, via detector modeling and characterization tasks. A secondary objective of this research is to investigate the material properties of X-ray photoconductors.