Estimation and compensation of the signal-to-noise ratios in radiography imaging under irregular detector gains

Image detectors, which are based on large flat panels, suffer from irregular gains due to the multiple circuits, such as line drives and amplifiers. In this paper, an image formation model, which considers the irregular gains of image detectors, is proposed, and a method for measuring the signal-to-noise ratio (SNR) of the acquired images from the detectors is introduced. The method uses several images taken under the same condition and is theoretically analyzed based on the proposed image formation model. A compensation scheme is then proposed for the method. It is shown that the method is equivalent to measuring the SNR from gain-corrected images, in which gain maps are employed. Despite the irregular gains, we can accurately measure SNRs with the quantum noise by employing the proposed compensation scheme for practical applications of digital radiography detectors.