Curved digital X-ray detectors

Abstract

A curved image sensor on plastic foil has been developed for cone beam computed tomography (CBCT) X-ray imaging. The image sensor of about 6x8cm(2) size has been built on a thin polyimide foil with an indium gallium zinc oxide (IGZO) backplane and an organic photodetectors (OPD) frontplane. A flexible cesium iodide (CsI) scintillator has been attached to the optical sensor with 480x640 pixels of 126 mu m size. Dark current density of the OPD was low with less than 10(-7)mA/cm(2) at -2V, while an external quantum efficiency (EQE) of about 50% was reached in the visible wavelength range matched to the scintillator output. The image quality of the digital X-ray detector allowed for 3D reconstruction images of a bone phantom on a rotating stage with a lab setup. The curved detector with 32cm curvature radius opens up the path for very compact CBCT gantries with largely reduced footprint.