A low-dose high contrast digital mammography system (DigiMAM)

Abstract

Hybrid pixel detector arrays that convert X-rays directly into charge signals are under development at NOVA for application to digital mammography. This technology also has wide application possibilities in other fields of radiology and also in industrial imaging for applications in nondestructive evaluation and inspection. These detectors have potentially superior properties compared to either emulsion based film, which has non-linear response to X-rays, or phosphor-based detectors in which there is an intermediate step of X-ray to light photons and light photons to electron-hole pairs conversion. Potential advantages of direct conversion detectors are high quantum efficiencies (QE) of 98% or higher (for 0.3 mm thick CdZnTe detector with 20 keV X-rays), improved contrast, high sensitivity and low intrinsic noise. These factors are expected to contribute to high detective quantum efficiency (DQE). The prototype hybrid pixel detector developed has 50/spl times/50 microns pixel size, is designed to have linear response to X-rays, and can support a dynamic range of 14 bits. The detector arrays are lightweight and can be packaged compactly, facilitating their incorporation into a digital mammography system or into other clinical radiology and industrial imaging applications where high sensitivity, excellent contrast, high resolution, and high dynamic range are required. Here, the authors report on tests of the first full size prototype readout ASIC chips hybridized with either silicon or CdZnTe detector arrays and present initial results and images.