Intelligent Pixel Architectures for Digital Medical Imaging Applications

Abstract

The most widely used architecture in large area amorphous silicon (a-Si) flat panel imagers is a passive pixel sensor (PPS), which consists of a detector and a readout switch. While the PPS has the advantage of being compact and amenable towards high-resolution imaging, reading small PPS output signals requires external column charge amplifiers that produce additional noise and reduce the minimum readable sensor input signal. This work presents current mediated amorphous silicon active pixel readout circuits based on four, three and two transistor designs that perform on-pixel amplification of noise-vulnerable sensor input signals to minimize the effect of external readout noise sources associated with "off-chip" charge amplifiers. The on-pixel amplifiers appear promising for use in fast readout, noise-sensitive, large area, digital medical imaging applications such as dual mode radiography/fluoroscopy and mammography tomosynthesis.