A method includes extracting a fully sampled fixed kVp sinogram for a pre-determined kVp of interest from an under-sampled mixed kVp sinogram generated from a switched kVp computed tomography scan. A system includes a fixed sinogram extractor that extracts a fully sampled fixed kVp sinogram from an under-sampled mixed kVp sinogram from a switched kVp computed tomography scan. A method includes de-noising at least one of a fully sampled fixed kVp sinogram extracted from an under-sampled mixed kVp sinogram or the under-sampled mixed kVp sinogram by smoothing lower kVp measurements of the sinograms and sharpening higher kVp measurements of the sinograms.
