Patent ID: 8628241

Claim:
A method for calibrating a CT system including at least one focus-detector combination having a quanta-counting detector with a plurality of detector elements, the focus-detector combination being configured to rotate around a measurement region and a system axis of the CT system, the focus-detector combination being configured to emit an X-ray bundle having an X-ray energy spectrum over an energy range, the method comprising: arranging at least one phantom in the measurement region such that each measurement beam of the focus-detector combination passes at least once through an area which results in a maximum attenuation and at least once through an area which results in minimum attenuation; performing at least one first scanning of the measurement region having the arranged at least one phantom, the first scanning being carried out from a plurality of projection angles arranged around an orbit of the focus-detector combination; performing at least one second scanning of the measurement region without the at least one phantom, the second scanning being carried out over a plurality of dosimetry power values; forming a scatter plot for each of the plurality of detector elements and each of the dosimetry power values, the scatter plot including a comparison between actual attenuation values and theoretical attenuation values of beams spatially identical to one another, the actual attenuation values being calculated based on measured values obtained by the quanta-counting detector during the first and second scanning, each of the theoretical attenuation values being associated with one of the plurality of dosimetry power values; determining at least one transfer function between the theoretical attenuation values and the actual attenuation values for each detector element; and calibrating the CT system based on the determined at least one transfer function.