Real-time diagnostic imaging with a novel x-ray detector with multiple screen-CCD sensors

In reference 1 we have presented the principle of an X-ray detector based upon a screen coupled to an array of multiple CCD sensors. In reference 2 we focus on the characterization of the image quality: resolution (MTF) and noise behavior in the overlap area. Simple (and cheap) low F# lenses likely show distortion which means that not all imaged pixels have the same magnification. This may affect resolution. Lenses with (some) barrel distortion have the benefit of less vignetting. The correction of distortion in combination with a rotation adjustment requires interpolation. Interpolation affects the noise properties so care must be taken in order to avoid that the noise characterization of the reconstructed image mosaic i.e. the noise texture becomes spatially non uniform. We present an analysis of the influence of lens distortion and interpolation in cases of small rotation correction on the image mosaic. The image processing appears not to diminish the image quality provided the processing parameters are set correctly. The calibration of the imaging mosaic geometry is crucial. We therefore present a robust extraction algorithm. In this paper our main interest is on MTF and quantum noise properties. The lab prototype hardware is designed such (cubic spline interpolation) that also the lens distortion can be compensated. For this purpose ASICs are designed by the company AEMICS. This enables relative cheap optical components with low F# and a short building length. We have obtained and will present radiographic exposures of static phantoms.