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Proceedings Paper

Photodiode gain calibration of flat dynamic x-ray detectors using reset light
Author(s): Burkhard A. Groh; Bernhard Sandkamp; Mathias Hoernig; Volker K. Heer; Falko Busse; Thierry Ducourant
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Paper 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.

Paper Details

Date Published: 3 May 2002
PDF: 9 pages
Proc. SPIE 4682, Medical Imaging 2002: Physics of Medical Imaging, (3 May 2002); doi: 10.1117/12.465587
Show Author Affiliations
Burkhard A. Groh, Siemens Medical Solutions (Germany)
Bernhard Sandkamp, Siemens Medical Solutions (Germany)
Mathias Hoernig, Siemens Medical Solutions (Germany)
Volker K. Heer, Siemens Medical Solutions (Germany)
Falko Busse, Philips Research Labs. (Germany)
Thierry Ducourant, Trixell SAS (France)

Published in SPIE Proceedings Vol. 4682:
Medical Imaging 2002: Physics of Medical Imaging
Larry E. Antonuk; Martin Joel Yaffe, Editor(s)

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