Dual-energy CT (DECT) scan mode was introduced in 2006. It uses two different X-ray energy spectra simultaneously to obtain additional information on tissue composition . The basic principle of DECT is the acquisition of two datasets with different energy spectra, from the same anatomic location . These spectra are generated with different tube potentials, by switching the voltage of one X-ray tube or by running two tubes at different voltages at the same time. DECT information can then be gained from two absorption measurements  in contrast to only one in a conventional CT.