A selenium-based flat-panel direct converter detector suitable for digital mammography was developed. The detector is based on a TFT-array with a resolution of 2816 X 2048 pixels, and a pixel pitch of 85 micrometers . Although the geometric fill factor for each pixel is around 70% , the effective fill factor for the detector is closer to 88% due to internal electric field shaping within the selenium layer. A selenium multilayer p-i-n structure of 200 micrometers was deposited onto the array by selectively doping the regions near each contact to produce unipolar conducting blocking layers. This structure absorbs more than 95% of a typical mammography beam.