Dual-layer flat panel detector with a-Se top layer for opportunistic screening of coronary artery calcium: a simulation study

Single exposure dual energy Dual-Layer (DL) Flat-Panel Detectors (FPD) are an approach to acquisition technology for x-ray imaging applications. It provides the advantages of enabling dual energy exposures in a single shot, avoiding motion artifacts created by respiratory or cardiac motion, and creating spectral separation to improve tissue specificity. We are investigating the effect of the top layer detector of a DL FPD by comparing two configurations (indirect vs. direct top layer conversion). We are interested in replacing the top layer scintillator detector for a direct conversion detector, made of amorphous selenium (a-Se), to improve image quality. Due to the photoconductive properties of a -Se, we will demonstrate that our design may improve the spatial resolution and high-frequency response of the x-ray image. The merit of developing these detectors lies in the possibility of opportunistic screening for quantifying coronary artery calcium (CAC), deteunining bone mineral density (i.e., osteoporosis), and characterizing renal stones through improvements to high-contrast visualization. In this work, we simulate the a-Se top layer detector to optimize the design parameters (e.g., the layer thickness and pixel pitch) for direct conversion to maintain spectral separation compared to that provided by a 200 mu m cesium iodide (CsI) indirect conversion layer and improve image quality.