When ESe is increased to > 90 V/mum, avalanche multiplication occurs. These signals can be stored and read out in the same fashion as in existing flat-panel detectors. Under an electric field ESe, the a-Se is sensitive to light and converts the optical photons emitted from CsI into electronic signal. The detector consists of an amorphous selenium (a-Se) photoconductor optically coupled to a structured cesium iodide (CsI) scintillator. Theory and measurements indicate that the C-APS pixel architecture is promising for diagnostic medical imaging modalities including low noise, real-time fluoroscopy.Ī new concept - an indirect flat-panel detector with avalanche gain - for low dose x-ray imaging has been proposed. In addition, the performance of C-APS amplified pixels is measured from both, a-Si TFT metastability and noise performance perspectives. Preliminary tests indicate linear performance, and a programmable circuits gain via choice of supply voltage and sampling time. Building upon previous research into active pixel sensor (APS) based amplified pixel readout circuits, this work investiates a current-mediated APS (C-APS) x-ray detection array for diagnostic medical imaging applications. While the PPS has the advantage of being compact and amenable towards high-resolution imaging, the data line capacitance, resistance, and the column charge amplifiers add a large noise component to the PPS that reduces the minimum readable sensor input signal. The most widely used pixel architecture is a passive pixel sensor (PPS) where the pixel consists of a detector and an a-Si:H thin-film transistor readout switch.
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