Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Introduction to Dual-Energy Computed Tomography

Introduction to Dual-Energy Computed Tomography EDITORIAL Introduction to Dual-Energy Computed Tomography Allen D. Elster, MD, FACR Dear JCAT Readers, his month, we have quite a treat for you indeed—a special issue devoted to dual-energy computed T tomography (DECT). For those of you not very familiar with this technology, hopefully you will find the following brief discussion helpful. Also known as “spectral imaging,” DECT traces its conceptual origins to the late 1970s concomi- tant with the initial deployment of conventional or single-energy CT systems. Only within the last 5 to 10 years, however, have scanner technology and postprocessing capabilities improved sufficiently to al- low DECT to become widely available commercially. Conventional (single-energy) CT systems typically utilize a single x-ray beam with a band of ener- gies ranging from 70 to 140 kVp (120 kVp most commonly used). Image contrast reflects differences in photon attenuation, which in turn depends on the inner shell electron binding energies (k-edge) of each tissue. The physical principle underlying DECT is that attenuation of various materials measured in Hounsfield units is not constant but can be manipulated by changing incident x-ray beam energy levels. Water and most soft tissues demonstrate only small differences in attenuation as a function of energy level. Materials with high atomic numbers such as metals and iodine, however, display large attenuation differences as photo energies increase. Dual-energy CT scanners typically emit x-rays and record attenuation in both low (80 kVp) and high (140 kVp) energy ranges. With this simultaneously acquired data, it is possible to simulate images performed at a single arbitrary photon level such as 40 or 100 kVp. Such synthetic images are called vir- tual monochromatic or monoenergetic images. Decomposition algorithms applied to these data also al- low material-specific images to be generated, such as blood, iodine, fat, or water (also known as “virtual unenhanced”)maps. At least 3 different strategies have been utilized by vendors to perform DECT. Dual-source DECT (popularized by Siemens) uses 2 x-ray tubes operating at different voltages and 2 sets of detectors. Single-source DECT (popularized by GE) uses only 1 set of detectors and 1 x-ray tube, the latter quickly switching between high and low energies. Detector-based spectral CT (popularized by Philips) uses a single broad-energy x-ray tube with double-layer detectors to discriminate between energy levels. The articles in our special JCAT issue review and highlight various DECT techniques and their clin- ical applications in the brain, lungs, heart, and abdomen. Hopefully there is something of interest for everyone here. Happy reading! From the Department of Radiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO. Correspondence to: Allen D. Elster, MD, FACR, Mallinckrodt Institute of Radiology, 216 S Kingshighway Blvd, St Louis, MO 63110 (e‐mail: aelster@wustl.edu). The author declares no conflict of interest. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/RCT.0000000000000827 J Comput Assist Tomogr � Volume 00, Number 00, Month 2018 www.jcat.org 1 Copyright © 2018 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. This paper can be cited using the date of access and the unique DOI number which can be found in the footnotes. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Computer Assisted Tomography Wolters Kluwer Health

Introduction to Dual-Energy Computed Tomography

Elster, Allen D.
Journal of Computer Assisted Tomography , Volume Publish Ahead of Print – Jun 1, 2018
Download PDF
1 page

Loading next page...
 
/lp/wolters-kluwer-health/introduction-to-dual-energy-computed-tomography-Ph9jk5f1iN

References

References for this paper are not available at this time. We will be adding them shortly, thank you for your patience.

Publisher
Wolters Kluwer Health
Copyright
Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.
ISSN
0363-8715
eISSN
1532-3145
DOI
10.1097/RCT.0000000000000827
Publisher site
See Article on Publisher Site

Abstract

EDITORIAL Introduction to Dual-Energy Computed Tomography Allen D. Elster, MD, FACR Dear JCAT Readers, his month, we have quite a treat for you indeed—a special issue devoted to dual-energy computed T tomography (DECT). For those of you not very familiar with this technology, hopefully you will find the following brief discussion helpful. Also known as “spectral imaging,” DECT traces its conceptual origins to the late 1970s concomi- tant with the initial deployment of conventional or single-energy CT systems. Only within the last 5 to 10 years, however, have scanner technology and postprocessing capabilities improved sufficiently to al- low DECT to become widely available commercially. Conventional (single-energy) CT systems typically utilize a single x-ray beam with a band of ener- gies ranging from 70 to 140 kVp (120 kVp most commonly used). Image contrast reflects differences in photon attenuation, which in turn depends on the inner shell electron binding energies (k-edge) of each tissue. The physical principle underlying DECT is that attenuation of various materials measured in Hounsfield units is not constant but can be manipulated by changing incident x-ray beam energy levels. Water and most soft tissues demonstrate only small differences in attenuation as a function of energy level. Materials with high atomic numbers such as metals and iodine, however, display large attenuation differences as photo energies increase. Dual-energy CT scanners typically emit x-rays and record attenuation in both low (80 kVp) and high (140 kVp) energy ranges. With this simultaneously acquired data, it is possible to simulate images performed at a single arbitrary photon level such as 40 or 100 kVp. Such synthetic images are called vir- tual monochromatic or monoenergetic images. Decomposition algorithms applied to these data also al- low material-specific images to be generated, such as blood, iodine, fat, or water (also known as “virtual unenhanced”)maps. At least 3 different strategies have been utilized by vendors to perform DECT. Dual-source DECT (popularized by Siemens) uses 2 x-ray tubes operating at different voltages and 2 sets of detectors. Single-source DECT (popularized by GE) uses only 1 set of detectors and 1 x-ray tube, the latter quickly switching between high and low energies. Detector-based spectral CT (popularized by Philips) uses a single broad-energy x-ray tube with double-layer detectors to discriminate between energy levels. The articles in our special JCAT issue review and highlight various DECT techniques and their clin- ical applications in the brain, lungs, heart, and abdomen. Hopefully there is something of interest for everyone here. Happy reading! From the Department of Radiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO. Correspondence to: Allen D. Elster, MD, FACR, Mallinckrodt Institute of Radiology, 216 S Kingshighway Blvd, St Louis, MO 63110 (e‐mail: aelster@wustl.edu). The author declares no conflict of interest. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/RCT.0000000000000827 J Comput Assist Tomogr � Volume 00, Number 00, Month 2018 www.jcat.org 1 Copyright © 2018 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. This paper can be cited using the date of access and the unique DOI number which can be found in the footnotes.

Journal

Journal of Computer Assisted Tomography – Wolters Kluwer Health

Published: Jun 1, 2018

There are no references for this article.