<title>Development of thin-film flat-panel arrays for diagnostic and radiotherapy imaging</title>

Abstract

Since the design and fabrication of the first pixelated, two-dimensional, hydrogenated amorphous silicon image sensor arrays at Xerox, PARC, in 1988, a variety of milestones have been achieved including the first demonstration of high quality radiographic images of low- contrast, anatomical detail. Current array configurations and design rules offer the prospect of 100 micrometers pixel pitches over 30 by 30 cm2 areas in the next few years. Beyond this, present attempts to extend the size of the substrates to 100 cm on the diagonal by 1996 coupled with the possibility of three-dimensional thin-film electronics could eventually result in a revolution in many forms of x-ray imaging. Such arrays will present challenges in the design of the fast, analog, and digital electronic readout systems required to precisely match the characteristics of the arrays to those of the imaging needs. For such arrays, one of the most important parameters is the dynamic range. Early results are reported for the measured limits on this quantity as obtained through measurements from individual sensors and FETs as well as an improved lower limit as obtained by direct measurements of array pixels.