Spectral CT imaging: Technical principles of dual-energy CT and multi-energy photon-counting CT

Spectral computed tomography (CT) imaging encompasses a unique generation of CT systems based on a simple principle that makes use of the energy-dependent information present in CT images. Over the past two decades this principle has been expanded with the introduction of dual-energy CT systems. The first generation of spectral CT systems, represented either by dual-source or dual-layer technology, opened up a new imaging approach in the radiology community with their ability to overcome the limitations of tissue characterization encountered with conventional CT. Its expansion worldwide can also be considered as an important leverage for the recent groundbreaking technology based on a new chain of detection available on photon counting CT systems, which holds great promise for extending CT towards multi-energy CT imaging. The purpose of this article was to detail the basic principles and techniques of spectral CT with a particular emphasis on the newest technical developments of dual-energy and multi-energy CT systems. (c) 2022 The Authors. Published by Elsevier Masson SAS on behalf of Societe francaise de radiologie. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Automated summary

Spectral computed tomography (CT) imaging is a generation of CT systems that utilize the energy-dependent information in CT images. The introduction of dual-energy CT systems expanded this principle. The first generation of spectral CT systems overcame limitations of tissue characterization encountered with conventional CT and provided a new imaging approach. The global expansion of spectral CT is seen as an important leverage for extending CT towards multi-energy CT imaging based on photon counting CT systems.