1. An imaging system comprising: a high frequency electromagnetic energy source that emits a beam of high frequency electromagnetic energy toward an object to be imaged; a detector that receives high frequency electromagnetic energy emitted by the high frequency electromagnetic energy source and attenuated by the object; a data acquisition system (DAS) operably connected to the detector; and a computer operably connected to the DAS and programmed to: compute detector coefficients based on a static low kVp measurement and a static high kVp measurement; capture incident spectra at high and low kVp; compute effective X-ray incident spectra at high and low kVp using the captured incident spectra; scan a water phantom and normalize the computed detector coefficients to water; adjust the computed effective X-ray incident spectra based on the normalized detector coefficients; compute basis material decomposition functions using the adjusted X-ray incident spectra; and generate one or more basis material density images using the computed basis material decomposition functions.