Comparison of a-Si:H/CsI flat-panel digital imaging systems with CR-and CCD-based systems: image quality measurements

Abstract

The amorphous silicon/cesium iodide (a-Si:H/CsI:Tl) flat-panel imaging systems have recently become commercially available for both chest and mammographic imaging applications. This new detector technology is considered to be a significant improvement over CR techniques. In this work, we measured the image properties for two commercial flat-panel systems and compared them with those measured for CR and CCD based imaging systems. Image quality measurements related to detector properties such as linearity, MTF, NPS and DQE are presented and compared at selected chest and mammographic imaging techniques. Factors and issues related to these measurements are discussed. For chest imaging, the flat-panel system was found to have slightly lower MTFs but significantly higher DQEs than the CR system. For mammographic imaging, the CCD-based system was found to have the highest MTF, followed in order by the flat-panel and CR systems. The flat-panel system was found to have the highest DQEs, followed in the order by the CCD-based and CR systems. The DQEs of the flat-panel systems were found to increase with exposure while those of the CR systems decrease slightly with the exposure in both chest and mammographic imaging. The DQEs of the CCD-based system were found to vary little for exposures ranging from 1 to 30 mR.