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Stein T, Rau A, Russe MF, Arnold P, Faby S, Ulzheimer S, Weis M, Froelich MF, Overhoff D, Horger M, Hagen F, Bongers M, Nikolaou K, Schönberg SO, Bamberg F, Weiß J. Photon-Counting Computed Tomography - Basic Principles, Potenzial Benefits, and Initial Clinical Experience. ROFO-FORTSCHR RONTG 2023; 195:691-698. [PMID: 36863367 DOI: 10.1055/a-2018-3396] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
BACKGROUND Photon-counting computed tomography (PCCT) is a promising new technology with the potential to fundamentally change today's workflows in the daily routine and to provide new quantitative imaging information to improve clinical decision-making and patient management. METHOD The content of this review is based on an unrestricted literature search on PubMed and Google Scholar using the search terms "Photon-Counting CT", "Photon-Counting detector", "spectral CT", "Computed Tomography" as well as on the authors' experience. RESULTS The fundamental difference with respect to the currently established energy-integrating CT detectors is that PCCT allows counting of every single photon at the detector level. Based on the identified literature, PCCT phantom measurements and initial clinical studies have demonstrated that the new technology allows improved spatial resolution, reduced image noise, and new possibilities for advanced quantitative image postprocessing. CONCLUSION For clinical practice, the potential benefits include fewer beam hardening artifacts, radiation dose reduction, and the use of new contrast agents. In this review, we will discuss basic technical principles and potential clinical benefits and demonstrate first clinical use cases. KEY POINTS · Photon-counting computed tomography (PCCT) has been implemented in the clinical routine. · Compared to energy-integrating detector CT, PCCT allows the reduction of electronic image noise. · PCCT provides increased spatial resolution and a higher contrast-to-noise ratio. · The novel detector technology allows the quantification of spectral information. CITATION FORMAT · Stein T, Rau A, Russe MF et al. Photon-Counting Computed Tomography - Basic Principles, Potenzial Benefits, and Initial Clinical Experience. Fortschr Röntgenstr 2023; 195: 691 - 698.
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Affiliation(s)
- Thomas Stein
- Department of Diagnostic and Interventional Radiology, Medical Center-University of Freiburg, Germany
| | - Alexander Rau
- Department of Diagnostic and Interventional Radiology, Medical Center-University of Freiburg, Germany
| | - Maximilian Frederik Russe
- Department of Diagnostic and Interventional Radiology, Medical Center-University of Freiburg, Germany
| | - Philipp Arnold
- Department of Diagnostic and Interventional Radiology, Medical Center-University of Freiburg, Germany
| | - Sebastian Faby
- Computed Tomography, Siemens Healthcare GmbH, Forchheim, Germany
| | - Stefan Ulzheimer
- Computed Tomography, Siemens Healthcare GmbH, Forchheim, Germany
| | - Meike Weis
- Department of Radiology and Nuclear Medicine, University Medical Centre Mannheim, Germany
| | - Matthias F Froelich
- Department of Radiology and Nuclear Medicine, University Medical Centre Mannheim, Germany
| | - Daniel Overhoff
- Department of Radiology and Nuclear Medicine, University Medical Centre Mannheim, Germany
| | - Marius Horger
- Department of Radiology, University Hospitals Tübingen, Germany
| | - Florian Hagen
- Department of Radiology, University Hospitals Tübingen, Germany
| | - Malte Bongers
- Department of Radiology, University Hospitals Tübingen, Germany
| | | | - Stefan O Schönberg
- Department of Radiology and Nuclear Medicine, University Medical Centre Mannheim, Germany
| | - Fabian Bamberg
- Department of Diagnostic and Interventional Radiology, Medical Center-University of Freiburg, Germany
| | - Jakob Weiß
- Department of Diagnostic and Interventional Radiology, Medical Center-University of Freiburg, Germany
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Willemink MJ, Persson M, Pourmorteza A, Pelc NJ, Fleischmann D. Photon-counting CT: Technical Principles and Clinical Prospects. Radiology 2018; 289:293-312. [PMID: 30179101 DOI: 10.1148/radiol.2018172656] [Citation(s) in RCA: 491] [Impact Index Per Article: 81.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Photon-counting CT is an emerging technology with the potential to dramatically change clinical CT. Photon-counting CT uses new energy-resolving x-ray detectors, with mechanisms that differ substantially from those of conventional energy-integrating detectors. Photon-counting CT detectors count the number of incoming photons and measure photon energy. This technique results in higher contrast-to-noise ratio, improved spatial resolution, and optimized spectral imaging. Photon-counting CT can reduce radiation exposure, reconstruct images at a higher resolution, correct beam-hardening artifacts, optimize the use of contrast agents, and create opportunities for quantitative imaging relative to current CT technology. In this review, the authors will explain the technical principles of photon-counting CT in nonmathematical terms for radiologists and clinicians. Following a general overview of the current status of photon-counting CT, they will explain potential clinical applications of this technology.
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Affiliation(s)
- Martin J Willemink
- From the Department of Radiology (M.J.W., M.P., N.J.P., D.F.) and Stanford Cardiovascular Institute (D.F.), Stanford University School of Medicine, 300 Pasteur Dr, S-072, Stanford, CA 94305-5105; Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands (M.J.W.); Departments of Bioengineering (M.P., N.J.P.) and Electrical Engineering (N.J.P.), Stanford University, Stanford, Calif; Department of Radiology and Department of Imaging Sciences and Biomedical Informatics, Emory University School of Medicine, Atlanta, Ga (A.P.)
| | - Mats Persson
- From the Department of Radiology (M.J.W., M.P., N.J.P., D.F.) and Stanford Cardiovascular Institute (D.F.), Stanford University School of Medicine, 300 Pasteur Dr, S-072, Stanford, CA 94305-5105; Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands (M.J.W.); Departments of Bioengineering (M.P., N.J.P.) and Electrical Engineering (N.J.P.), Stanford University, Stanford, Calif; Department of Radiology and Department of Imaging Sciences and Biomedical Informatics, Emory University School of Medicine, Atlanta, Ga (A.P.)
| | - Amir Pourmorteza
- From the Department of Radiology (M.J.W., M.P., N.J.P., D.F.) and Stanford Cardiovascular Institute (D.F.), Stanford University School of Medicine, 300 Pasteur Dr, S-072, Stanford, CA 94305-5105; Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands (M.J.W.); Departments of Bioengineering (M.P., N.J.P.) and Electrical Engineering (N.J.P.), Stanford University, Stanford, Calif; Department of Radiology and Department of Imaging Sciences and Biomedical Informatics, Emory University School of Medicine, Atlanta, Ga (A.P.)
| | - Norbert J Pelc
- From the Department of Radiology (M.J.W., M.P., N.J.P., D.F.) and Stanford Cardiovascular Institute (D.F.), Stanford University School of Medicine, 300 Pasteur Dr, S-072, Stanford, CA 94305-5105; Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands (M.J.W.); Departments of Bioengineering (M.P., N.J.P.) and Electrical Engineering (N.J.P.), Stanford University, Stanford, Calif; Department of Radiology and Department of Imaging Sciences and Biomedical Informatics, Emory University School of Medicine, Atlanta, Ga (A.P.)
| | - Dominik Fleischmann
- From the Department of Radiology (M.J.W., M.P., N.J.P., D.F.) and Stanford Cardiovascular Institute (D.F.), Stanford University School of Medicine, 300 Pasteur Dr, S-072, Stanford, CA 94305-5105; Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands (M.J.W.); Departments of Bioengineering (M.P., N.J.P.) and Electrical Engineering (N.J.P.), Stanford University, Stanford, Calif; Department of Radiology and Department of Imaging Sciences and Biomedical Informatics, Emory University School of Medicine, Atlanta, Ga (A.P.)
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Ge Y, Ji X, Zhang R, Li K, Chen GH. K-edge energy-based calibration method for photon counting detectors. Phys Med Biol 2017; 63:015022. [PMID: 29072192 DOI: 10.1088/1361-6560/aa9637] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In recent years, potential applications of energy-resolved photon counting detectors (PCDs) in the x-ray medical imaging field have been actively investigated. Unlike conventional x-ray energy integration detectors, PCDs count the number of incident x-ray photons within certain energy windows. For PCDs, the interactions between x-ray photons and photoconductor generate electronic voltage pulse signals. The pulse height of each signal is proportional to the energy of the incident photons. By comparing the pulse height with the preset energy threshold values, x-ray photons with specific energies are recorded and sorted into different energy bins. To quantitatively understand the meaning of the energy threshold values, and thus to assign an absolute energy value to each energy bin, energy calibration is needed to establish the quantitative relationship between the threshold values and the corresponding effective photon energies. In practice, the energy calibration is not always easy, due to the lack of well-calibrated energy references for the working energy range of the PCDs. In this paper, a new method was developed to use the precise knowledge of the characteristic K-edge energy of materials to perform energy calibration. The proposed method was demonstrated using experimental data acquired from three K-edge materials (viz., iodine, gadolinium, and gold) on two different PCDs (Hydra and Flite, XCounter, Sweden). Finally, the proposed energy calibration method was further validated using a radioactive isotope (Am-241) with a known decay energy spectrum.
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Affiliation(s)
- Yongshuai Ge
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, United States of America. The first two authors (Y Ge and X Ji) made equal contributions to this work and are both considered as the first author
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