title: Dual- and Multi-Energy CT: Principles, Technical Approaches, and Clinical Applications.
abstract: In x-ray computed tomography (CT), materials having different elemental compositions can be represented by identical pixel values on a CT image (ie, CT numbers), depending on the mass density of the material. Thus, the differentiation and classification of different tissue types and contrast agents can be extremely challenging. In dual-energy CT, an additional attenuation measurement is obtained with a second x-ray spectrum (ie, a second "energy"), allowing the differentiation of multiple materials. Alternatively, this allows quantification of the mass density of two or three materials in a mixture with known elemental composition. Recent advances in the use of energy-resolving, photon-counting detectors for CT imaging suggest the ability to acquire data in multiple energy bins, which is expected to further improve the signal-to-noise ratio for material-specific imaging. In this review, the underlying motivation and physical principles of dual- or multi-energy CT are reviewed and each of the current technical approaches is described. In addition, current and evolving clinical applications are introduced.
authors: From the Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905.
authors: Cynthia H
authors: CH
authors: McCollough
authors: From the Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905.
authors: Shuai
authors: S
authors: Leng
authors: From the Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905.
authors: Lifeng
authors: L
authors: Yu
authors: From the Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905.
authors: Joel G
authors: JG
authors: Fletcher
mesh_terms: D000465:Algorithms; D006801:Humans; D015900:Radiography, Dual-Energy Scanned Projection; D014057:Tomography, X-Ray Computed / Q000379:methods*