8.19 – Amorphous Silicon Detectors

This chapter provides an overview of the technology behind active matrix flat-panel imagers (AMFPIs). The principle of operation of amorphous silicon (a-Si) thin film transistor array, and the direct and indirect conversion approaches for the detection of x-rays are described. For each conversion approach, a variety of different detector design and construction methods are reviewed, and their x-ray response estimated. The international standards for evaluating the imaging performance of x-ray detectors are presented, along with examples of published measurement results for commercial detectors in different categories. The temporal performance of both types of AMFPIs and the physical mechanisms of lag and ghosting are discussed. Finally, a brief overview of emerging flat-panel imaging detector technologies is provided.