Abstract: A method for determining a correction for beam hardening in CT images includes obtaining air scans at a plurality of kVp's, determining detection efficiencies for detector elements of the CT imaging apparatus, and estimating projection values through a combination of at least two different materials of different thicknesses. The method further includes determining a transfer function that translates the estimated projection values into ideal projection values for at least two of the different materials and storing the transfer function as the beam hardening correction for images of the CT imaging apparatus.

Abstract: A method for calibrating a computed tomographic imaging apparatus having a gantry, a radiation source operable at a plurality of kVp's, and a detector array having a plurality of detector elements includes using a system detection function to estimate signals of each detector element that would have been detected through air and through a given thickness of water to determine estimated datasets. The estimated datasets are used to determine data pair sets each comprising a normalized water projection value and an ideal projection value for each detector element. The method further includes determining and storing a representation of a mapping function of the normalized water projections values to the ideal projection values in a memory of the computed tomographic imaging apparatus as a spectral calibration of the computed tomographic imaging apparatus.