Dual-Energy and Spectral CT

The outline of this chapter is as follows. Given the fact that dual-energy CT and spectral CT were introduced commercially only in recent years, it is important to establish a basic understanding of the principles and concepts. Therefore, Section 12.1 presents some simple phantom observations to provide an intuitive, high-level explanation of the basic concept. Section 12.2 provides a theoretical basis of material differentiation and representation. Based on the theory that the attenuation coefficient of any material can be represented as a linear combination of two other materials, material decomposition approaches are discussed. Monochromatic image, effective atomic number, electron density, and other representations of spectral information are presented in Section 12.3. Section 12.4 presents different ways of acquiring dual-energy and spectral CT data. The final section presents some clinical examples of dual-energy and spectral CT.