3 May 2002 Photodiode gain calibration of flat dynamic x-ray detectors using reset light
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Abstract
Due to spatial gain differences of the photo diodes and inhomogeneities in the converter (CsI) a gain calibration is usually applied for flat dynamic X-ray detectors. This calibration is calculated from X-ray images. Using the reset light, integrated in the detector, a calibration of the photo diode gain is possible. Since neither the reset light intensity nor the X-ray field distribution in combination with the converter efficiency are spatially homogeneous the ratio of these two effects has to be measured and stored once in an X-ray reset-light map. In a reset light calibration the photo diode gain will be estimated and the final calibration is then calculated from this gain image and the stored X-ray reset-light map. The reset light gain image contains the same information as the X-ray image except the influence of the scintillator which should be very stable over time. Changes in the photo diode gain can easily and automatically be corrected using the reset light calibration. Defect pixels can be determined from the reset light gain images. This method would allow a continuous calibration during the lifetime of the detector without the need for any user interaction.
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Burkhard A. Groh, Burkhard A. Groh, Bernhard Sandkamp, Bernhard Sandkamp, Mathias Hoernig, Mathias Hoernig, Volker K. Heer, Volker K. Heer, Falko Busse, Falko Busse, Thierry Ducourant, Thierry Ducourant, "Photodiode gain calibration of flat dynamic x-ray detectors using reset light", Proc. SPIE 4682, Medical Imaging 2002: Physics of Medical Imaging, (3 May 2002); doi: 10.1117/12.465587; https://doi.org/10.1117/12.465587
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