A framework for performance characterization of energy‐resolving photon‐counting detectors.
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| Title: | A framework for performance characterization of energy‐resolving photon‐counting detectors. |
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| Authors: | Persson, Mats1 matspers@stanford.edu, Rajbhandary, Paurakh L.2, Pelc, Norbert J.3 |
| Source: | Medical Physics. Nov2018, Vol. 45 Issue 11, p4897-4915. 19p. |
| Subjects: | Photon counting, Photon detectors, Quantum efficiency, Spectral imaging, X-ray imaging |
| Abstract: | Purpose: Photon‐counting, energy‐resolving detectors are subject to intense research interest, and there is a need for a general framework for performance assessment of these detectors. The commonly used linear‐systems theory framework, which measures detector performance in terms of noise‐equivalent quanta (NEQ) and detective quantum efficiency (DQE) is widely used for characterizing conventional x‐ray detectors but does not take energy‐resolving capabilities into account. The purpose of this work is to extend this framework to encompass energy‐resolving photon‐counting detectors and elucidate how the imperfect energy response and other imperfections in real‐world detectors affect imaging performance, both for feature detection and for material quantification tasks. Method: We generalize NEQ and DQE to matrix‐valued quantities as functions of spatial frequency, and show how these matrices can be calculated from simple Monte Carlo simulations. To demonstrate how the new metrics can be interpreted, we compute them for simplified models of fluorescence and Compton scatter in a photon‐counting detector and for a Monte Carlo model of a CdTe detector with 0.5×0.5mm2 pixels. Results: Our results show that the ideal‐linear‐observer performance for any detection or material quantification task can be calculated from the proposed generalized NEQ and DQE metrics. We also demonstrate that the proposed NEQ metric is closely related to a generalized version of the Cramér‐Rao lower bound commonly used for assessing material quantification performance. Off‐diagonal elements in the NEQ and DQE matrices are shown to be related to loss of energy information due to imperfect energy resolution. The Monte Carlo model of the CdTe detector predicts a zero‐frequency dose efficiency relative to an ideal detector of 0.86 and 0.65 for detecting water and bone, respectively. When the task instead is to quantify these materials, the corresponding values are 0.34 for water and 0.26 for bone. Conclusions: We have developed a framework for assessing the performance of photon‐counting energy‐resolving detectors and shown that the matrix‐valued NEQ and DQE metrics contain sufficient information for calculating the dose efficiency for both detection and quantification tasks, the task having any spatial and energy dependence. This framework will be beneficial for the development and optimization of photon‐counting x‐ray detectors. [ABSTRACT FROM AUTHOR] |
| Copyright of Medical Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
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| Items | – Name: Title Label: Title Group: Ti Data: A framework for performance characterization of energy‐resolving photon‐counting detectors. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Persson%2C+Mats%22">Persson, Mats</searchLink><relatesTo>1</relatesTo><i> matspers@stanford.edu</i><br /><searchLink fieldCode="AR" term="%22Rajbhandary%2C+Paurakh+L%2E%22">Rajbhandary, Paurakh L.</searchLink><relatesTo>2</relatesTo><br /><searchLink fieldCode="AR" term="%22Pelc%2C+Norbert+J%2E%22">Pelc, Norbert J.</searchLink><relatesTo>3</relatesTo> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Medical+Physics%22">Medical Physics</searchLink>. Nov2018, Vol. 45 Issue 11, p4897-4915. 19p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Photon+counting%22">Photon counting</searchLink><br /><searchLink fieldCode="DE" term="%22Photon+detectors%22">Photon detectors</searchLink><br /><searchLink fieldCode="DE" term="%22Quantum+efficiency%22">Quantum efficiency</searchLink><br /><searchLink fieldCode="DE" term="%22Spectral+imaging%22">Spectral imaging</searchLink><br /><searchLink fieldCode="DE" term="%22X-ray+imaging%22">X-ray imaging</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Purpose: Photon‐counting, energy‐resolving detectors are subject to intense research interest, and there is a need for a general framework for performance assessment of these detectors. The commonly used linear‐systems theory framework, which measures detector performance in terms of noise‐equivalent quanta (NEQ) and detective quantum efficiency (DQE) is widely used for characterizing conventional x‐ray detectors but does not take energy‐resolving capabilities into account. The purpose of this work is to extend this framework to encompass energy‐resolving photon‐counting detectors and elucidate how the imperfect energy response and other imperfections in real‐world detectors affect imaging performance, both for feature detection and for material quantification tasks. Method: We generalize NEQ and DQE to matrix‐valued quantities as functions of spatial frequency, and show how these matrices can be calculated from simple Monte Carlo simulations. To demonstrate how the new metrics can be interpreted, we compute them for simplified models of fluorescence and Compton scatter in a photon‐counting detector and for a Monte Carlo model of a CdTe detector with 0.5×0.5mm2 pixels. Results: Our results show that the ideal‐linear‐observer performance for any detection or material quantification task can be calculated from the proposed generalized NEQ and DQE metrics. We also demonstrate that the proposed NEQ metric is closely related to a generalized version of the Cramér‐Rao lower bound commonly used for assessing material quantification performance. Off‐diagonal elements in the NEQ and DQE matrices are shown to be related to loss of energy information due to imperfect energy resolution. The Monte Carlo model of the CdTe detector predicts a zero‐frequency dose efficiency relative to an ideal detector of 0.86 and 0.65 for detecting water and bone, respectively. When the task instead is to quantify these materials, the corresponding values are 0.34 for water and 0.26 for bone. Conclusions: We have developed a framework for assessing the performance of photon‐counting energy‐resolving detectors and shown that the matrix‐valued NEQ and DQE metrics contain sufficient information for calculating the dose efficiency for both detection and quantification tasks, the task having any spatial and energy dependence. This framework will be beneficial for the development and optimization of photon‐counting x‐ray detectors. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Medical Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1002/mp.13172 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 19 StartPage: 4897 Subjects: – SubjectFull: Photon counting Type: general – SubjectFull: Photon detectors Type: general – SubjectFull: Quantum efficiency Type: general – SubjectFull: Spectral imaging Type: general – SubjectFull: X-ray imaging Type: general Titles: – TitleFull: A framework for performance characterization of energy‐resolving photon‐counting detectors. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Persson, Mats – PersonEntity: Name: NameFull: Rajbhandary, Paurakh L. – PersonEntity: Name: NameFull: Pelc, Norbert J. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 11 Text: Nov2018 Type: published Y: 2018 Identifiers: – Type: issn-print Value: 00942405 Numbering: – Type: volume Value: 45 – Type: issue Value: 11 Titles: – TitleFull: Medical Physics Type: main |
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