A novel X-ray detector with multiple screen-CCD sensors for real-time diagnostic imaging. Physics of Medical Imaging

In this contribution we propose an alternative x-ray detector based upon multiple screen-CCD sensor combinations. The impinging x-ray quanta are detected by a scintillator screen (e.g. CsI) and converted to light photons (typ. 1200 photons per absorbed x-ray quantum). We propose a number of lens-CCD sensors for standard video performance to detect the light photons coming out of an x-ray intensifying screen. Due to the smaller demagnification the coupling efficiency is better even with moderate quality (F number) lenses. We thus obtain a matrix of subimages, the system is constructed such that the subimages partially overlap. With digital image processing we construct from the subimages a single high quality image. Special hardware (incl. ASICS) has been developed for imaging at video rates, enabling (almost) fluoroscopy with this new detector. We show a viable digital x-ray imaging detector concept by means of our 2 by 2 CCD camera prototype and real-time processing engine. The image quality, MTF and noise properties are satisfactory and well in the diagnostic application range.