A CT scanner for multiple energy CT scanning of a subject having an X-Ray source adapted to rotate about the subject and a detector array, having a plurality of detector elements, adapted to acquire attenuation data for X-Rays that have been attenuated by a subject disposed between said X-Ray source and said detector array, said detector array comprising at least two types of detector element, which are differ by their spectral response. The scanner is adapted to generate images associated with the different X-Ray energy spectra.