A CCD Based Digital Detector for Whole-Breast Digital Mammography

Abstract

We are developing an 18×27cm digital x-ray detector for whole-breast mammography based on CCD imaging technology [1]. In this paper we report the performance of a 10×20 cm, 2-CCD prototype we have built and tested. Similar to a film system, this detector uses a phosphor screen to convert an x-ray image to visible light. In the digital system the light photons are transferred onto a charge-coupled device (CCD) by a demagnifying fiber optic taper. Dedicated electronics then transfer the image to a PC based viewing station. The dynamic range of the detector is roughly 375 times greater than that of a typical screen film [2]. This difference increases our ability to discriminate low contrast differences in tissue, and allows image exposure to be determined solely by the desired signal-to-noise ratio and acceptable patient dose, whereas in a non-digital system, exposure is determined by film’s narrow linear response range.