TABLE 1.

Features of Dual-Energy CT Hardware Platforms

Hardware Platform	Advantages	Disadvantages
Dual-source CT	Different beam filtration for each tube results in wider spectral separation and improved material discrimination Flexible adjustment of tube current for each tube optimizes image quality	No projection-domain dual-energy processing for helical scans Second tube has limited scanning field of view, requiring careful patient positioning for large patients
Rapid kV switching	Allows dual-energy processing in projection space Allows creation of monochromatic images, which have the potential to reduce beam-hardening artifacts	Same beam filtration for both low- and high-energy scanning, limited spectra separation Difficult to adjust tube current for low- and high-energy scans separately, usually leading to inferior image quality in the low-energy scan
Multilayer sandwich detectors (prototype)	Same data-acquisition geometry as in conventional single-energy CT; low-energy and high-energy data are perfectly aligned	Potential for significant spectra overlap, which may compromise performance of material characterization Difficult to achieve similar image quality in low-energy data as in high-energy data