Patent ID: 7391844

Claim:
A method for determining a correction for beam hardening in CT images in a CT imaging apparatus, said method comprising: obtaining air scans at a plurality of kVp's; detennining detection efficiencies for detector elements of the CT imaging apparatus; estimating a first set of projection values through a combination of at least two different materials of different thicknesses based on at least a combined material attenuation of the beam filters positioned between a radiation source and the detector elements, said different materials are objects other than the beam filters; estimating a second set of projection values through one of the two different materials based on the combined material attenuation of the beam filters: spectrally calibrating said materials utilizing a detector detection efficiency function, said spectral calibration for said different materials thereby becoming multiple material calibration data; detennining a transfer function that translates the first set of estimated projection values and the second set of estimated projection values into ideal projection values for at least two of said different materials; and storing the transfer function as the beam hardening calibration function for images of the CT imaging apparatus.