Detective efficiency of photon counting detectors with spectral degradation and crosstalk.
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| Title: | Detective efficiency of photon counting detectors with spectral degradation and crosstalk. |
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| Authors: | Rajbhandary, Paurakh L.1 (AUTHOR) paurakh@stanford.edu, Persson, Mats2 (AUTHOR), Pelc, Norbert J.3 (AUTHOR) |
| Source: | Medical Physics. Jan2020, Vol. 47 Issue 1, p27-36. 10p. |
| Subjects: | Photon detectors, Photon counting, Crosstalk, Nyquist frequency, Quantum efficiency, Underwater noise |
| Abstract: | Purpose: Charge sharing and migration of scattered and fluorescence photons in an energy discriminating photon counting detector (PCD) degrade the detector's energy response and can cause a single incident photon to be registered as multiple events at different energies among neighboring pixels, leading to spatio‐energetic correlation. Such a correlation in conventional linear, space‐invariant imaging system can be usefully characterized by the frequency dependent detective quantum efficiency DQE(f). Defining and estimating DQE(f) for PCDs in a manner consistent with that of conventional detectors is complicated because the traditional definition of DQE(f) does not address spectral information. Methods: We introduce the concept of presampling spectroscopic detective quantum efficiency, DQEs(f), and present an analysis of it for CdTe PCDs using a spatial domain method that starts from a previously described analytic computation of spatio‐energetic crosstalk. DQEs(f) is estimated as the squared signal‐to‐noise ratio of the amplitude of a small‐signal sinusoidal modulation of the object (cortical bone) thickness at frequency f estimated using data from the detector under consideration compared that obtained from the photon distribution incident on the detector. DQEs for material decomposition (spectral) and effective monoenergetic imaging tasks for different pixel pitch is studied based on the multipixel Cramér‐Rao lower bound (CRLB) that accounts for inter pixel basis material correlation. Effective monoenergetic DQEs is estimated from the CRLB of a linear weighted combination of basis materials, and its energy dependence is also studied. Results: Zero frequency DQEs for the spectral task was ~18%, 25%, and 34% for 250 μm, 500 μm, and 1 mm detector pixels respectively. Inter pixel signal correlation results in positive noise correlation between same basis material estimates of neighboring pixels, resulting in least impact on DQEs at the detector's Nyquist frequency. Effective monoenergetic DQEs(0) at the optimal energy is relatively tolerant of spectral degradation (85–91% depending on pixel size), but is highly dependent on the selected effective energy, with maximum variation (in 250 μm pixels) of 17% to 85% for effective energy between 30 to 120 keV. Conclusions: Our results show that spatio‐energetic correlations degrade DQEs(f) beyond what is lost by poor spectral response in a single detector element. The positive correlation between computed single basis material values in neighboring pixels results in the penalty to DQEs(f) to be the least at the Nyquist frequency of the detector. It is desirable to reduce spectral degradation and crosstalk to minimize the impact on system performance. Larger pixels sizes have better spatio‐energetic response due to lower charge sharing and escape of scatter and K‐fluorescence photons, and therefore higher DQEs(0). Effective monoenergetic DQEs(0) at the optimal energy is much less affected by spectral degradation and crosstalk compared to DQEs for spectral tasks. [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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| Header | DbId: egs DbLabel: Engineering Source An: 141252316 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Detective efficiency of photon counting detectors with spectral degradation and crosstalk. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Rajbhandary%2C+Paurakh+L%2E%22">Rajbhandary, Paurakh L.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> paurakh@stanford.edu</i><br /><searchLink fieldCode="AR" term="%22Persson%2C+Mats%22">Persson, Mats</searchLink><relatesTo>2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Pelc%2C+Norbert+J%2E%22">Pelc, Norbert J.</searchLink><relatesTo>3</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Medical+Physics%22">Medical Physics</searchLink>. Jan2020, Vol. 47 Issue 1, p27-36. 10p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Photon+detectors%22">Photon detectors</searchLink><br /><searchLink fieldCode="DE" term="%22Photon+counting%22">Photon counting</searchLink><br /><searchLink fieldCode="DE" term="%22Crosstalk%22">Crosstalk</searchLink><br /><searchLink fieldCode="DE" term="%22Nyquist+frequency%22">Nyquist frequency</searchLink><br /><searchLink fieldCode="DE" term="%22Quantum+efficiency%22">Quantum efficiency</searchLink><br /><searchLink fieldCode="DE" term="%22Underwater+noise%22">Underwater noise</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Purpose: Charge sharing and migration of scattered and fluorescence photons in an energy discriminating photon counting detector (PCD) degrade the detector's energy response and can cause a single incident photon to be registered as multiple events at different energies among neighboring pixels, leading to spatio‐energetic correlation. Such a correlation in conventional linear, space‐invariant imaging system can be usefully characterized by the frequency dependent detective quantum efficiency DQE(f). Defining and estimating DQE(f) for PCDs in a manner consistent with that of conventional detectors is complicated because the traditional definition of DQE(f) does not address spectral information. Methods: We introduce the concept of presampling spectroscopic detective quantum efficiency, DQEs(f), and present an analysis of it for CdTe PCDs using a spatial domain method that starts from a previously described analytic computation of spatio‐energetic crosstalk. DQEs(f) is estimated as the squared signal‐to‐noise ratio of the amplitude of a small‐signal sinusoidal modulation of the object (cortical bone) thickness at frequency f estimated using data from the detector under consideration compared that obtained from the photon distribution incident on the detector. DQEs for material decomposition (spectral) and effective monoenergetic imaging tasks for different pixel pitch is studied based on the multipixel Cramér‐Rao lower bound (CRLB) that accounts for inter pixel basis material correlation. Effective monoenergetic DQEs is estimated from the CRLB of a linear weighted combination of basis materials, and its energy dependence is also studied. Results: Zero frequency DQEs for the spectral task was ~18%, 25%, and 34% for 250 μm, 500 μm, and 1 mm detector pixels respectively. Inter pixel signal correlation results in positive noise correlation between same basis material estimates of neighboring pixels, resulting in least impact on DQEs at the detector's Nyquist frequency. Effective monoenergetic DQEs(0) at the optimal energy is relatively tolerant of spectral degradation (85–91% depending on pixel size), but is highly dependent on the selected effective energy, with maximum variation (in 250 μm pixels) of 17% to 85% for effective energy between 30 to 120 keV. Conclusions: Our results show that spatio‐energetic correlations degrade DQEs(f) beyond what is lost by poor spectral response in a single detector element. The positive correlation between computed single basis material values in neighboring pixels results in the penalty to DQEs(f) to be the least at the Nyquist frequency of the detector. It is desirable to reduce spectral degradation and crosstalk to minimize the impact on system performance. Larger pixels sizes have better spatio‐energetic response due to lower charge sharing and escape of scatter and K‐fluorescence photons, and therefore higher DQEs(0). Effective monoenergetic DQEs(0) at the optimal energy is much less affected by spectral degradation and crosstalk compared to DQEs for spectral tasks. [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.13889 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 10 StartPage: 27 Subjects: – SubjectFull: Photon detectors Type: general – SubjectFull: Photon counting Type: general – SubjectFull: Crosstalk Type: general – SubjectFull: Nyquist frequency Type: general – SubjectFull: Quantum efficiency Type: general – SubjectFull: Underwater noise Type: general Titles: – TitleFull: Detective efficiency of photon counting detectors with spectral degradation and crosstalk. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Rajbhandary, Paurakh L. – PersonEntity: Name: NameFull: Persson, Mats – PersonEntity: Name: NameFull: Pelc, Norbert J. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 01 Text: Jan2020 Type: published Y: 2020 Identifiers: – Type: issn-print Value: 00942405 Numbering: – Type: volume Value: 47 – Type: issue Value: 1 Titles: – TitleFull: Medical Physics Type: main |
| ResultId | 1 |
