Abstract
Dual energy CT (DECT) refers to the acquisition of CT images at two energy spectra and can provide information about tissue composition beyond that obtainable by conventional CT. The attenuation of a photon beam varies depends on the atomic number and density of the attenuating material and the energy of the incoming photon beam. This differential attenuation of the beam at varying energy levels forms the basis of DECT imaging and enables separation of materials with different atomic numbers but similar CT attenuation. DECT can be used to detect and quantify materials like iodine, calcium, or uric acid. Several post-processing techniques are available to generate virtual non-contrast images, iodine maps, virtual mono-chromatic images, Mixed or weighted images and material specific images. Although initially the concept of dual energy CT was introduced in 1970, it is only over the past two decades that it has been extensively used in clinical practice owing to advances in CT hardware and post-processing capabilities. There are numerous applications of DECT in Emergency radiology including stroke imaging to differentiate intracranial hemorrhage and contrast staining, diagnosis of pulmonary embolism, characterization of incidentally detected renal and adrenal lesions, to reduce beam and metal hardening artifacts, in identification of uric acid renal stones and in the diagnosis of gout. This review article aims to provide the emergency radiologist with an overview of the physics and basic principles of dual energy CT. In addition, we discuss the types of DECT acquisition and post processing techniques including newer advances such as photon-counting CT followed by a brief discussion on the applications of DECT in Emergency radiology.
Highlights
Multidetector Computed Tomography (MDCT) has revolutionized diagnostic radiology and has become the workhorse of medical imaging, especially in the emergency department [1]
MDCT has been performed with a “single energy” where a single polychromatic x-ray beam is generated by a single source and detected by a single detector array
Dual Energy CT Physics levels allows for differentiation of materials with different atomic numbers which may have the same CT attenuation
Summary
Multidetector Computed Tomography (MDCT) has revolutionized diagnostic radiology and has become the workhorse of medical imaging, especially in the emergency department [1]. Dual energy and multi-energy CT involve acquiring images at two or more energy spectra at different kilovoltage peaks (kVp). Dual Energy CT Physics levels allows for differentiation of materials with different atomic numbers which may have the same CT attenuation. The concept of dual energy CT acquisition was initially introduced in the early 1970s, it has been only over the past two decades that it has been used widely in routine practice. The purpose of this article is to discuss the basic principles of DECT, considerations for image acquisition and techniques, and a brief overview of clinical applications of DECT in emergency radiology. Specific clinical applications of DECT are available elsewhere in this issue
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