title: Digital radiology using active matrix readout of amorphous selenium: construction and evaluation of a prototype real-time detector.
abstract: The goal of the present work is to develop a large area, flat-panel solid-state detector for both digital radiography and fluoroscopy. The proposed detector employs a photoconductive layer of amorphous selenium (a-Se) to convert x rays into charge. The charge image formed by the a-Se layer is electronically read out in situ using a two dimensional array of thin film transistors (TFTs), or active matrix. Since the active matrix readout is capable of producing x-ray images in real-time, it can potentially be applied in both radiography and fluoroscopy. In this paper, the imaging performance of this concept is investigated using a prototype x-ray imaging detector. The designs for the active matrix, the peripheral electronic circuits, and the image acquisition system are described. Measurements of x-ray imaging properties of the prototype detector, i.e., x-ray sensitivity, presampling modulation transfer function (MTF), and noise power spectrum (NPS), were performed, and from which the spatial frequency dependent detective quantum efficiency (DQE) of the prototype was derived. The experimental results are in agreement with the results of our theoretical analysis. The factors affecting the imaging performance and methods of improvement in the future are discussed.
authors.affiliation: Department of Medical Biophysics, University of Toronto, Sunnybrook Health Science Centre, Ontario, Canada. zhao@phoebus.sunnybrook.utoronto.ca
authors.forename: W
authors.initials: W
authors.lastname: Zhao
authors.forename: I
authors.initials: I
authors.lastname: Blevis
authors.forename: S
authors.initials: S
authors.lastname: Germann
authors.forename: J A
authors.initials: JA
authors.lastname: Rowlands
authors.forename: D
authors.initials: D
authors.lastname: Waechter
authors.forename: Z
authors.initials: Z
authors.lastname: Huang
mesh_terms: D005471:Fluoroscopy / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted; D008962:Models, Theoretical; D011857:Radiographic Image Interpretation, Computer-Assisted; D012643:Selenium; D012680:Sensitivity and Specificity; D014965:X-Rays
chemical_list: D012643:Selenium