Spatio-energetic cross-talk in photon counting detectors: numerical detector model (PcTK) and workflow for CT image quality assessment

Taguchi, Katsuyuki; Stierstorfer, Karl; Polster, Christoph; Lee, Okkyun; Kappler, S.

doi:10.1117/12.2293881

Cited by 16 publications

(43 citation statements)

References 4 publications

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“…The transport of x‐ray photons into a CdTe substrate was performed using a Monte Carlo code, GEANT4. While we chose to use in‐house Monte Carlo codes for this work, an open‐source toolkit that implements a similar approach has recently been made available . Alternatives to Monte Carlo have also been demonstrated that may improve the computational efficiency of simulation .…”

Section: Methodsmentioning

confidence: 99%

Digital count summing vs analog charge summing for photon counting detectors: A performance simulation study

Hsieh

Sjölin

2018

Medical Physics

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Section: Methodsmentioning

confidence: 99%

Digital count summing vs analog charge summing for photon counting detectors: A performance simulation study

Hsieh

Sjölin

2018

Medical Physics

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“…Almost all of n ‐tuple counting does not involve neighboring pixels because (a) the probability of triple‐ and quadruple‐counting is less than 1.5% (see Table of Ref. ); and (b) the probability of triple‐ and quadruple‐counting at a pixel boundary is even smaller. Thus, most of spill‐in events produce one count at the output‐pixel‐of‐interest, while producing another count at a neighboring pixel.…”

Section: Discussionmentioning

confidence: 99%

“…We used the PCD cross‐talk model, Photon Counting Toolkit (PcTK) version 3.2, which had been made available to academic researcher free of charge (pctk.jhu.edu), with parameters for PCDs we will specify in Section 2.D. The PcTK has been extensively evaluated by a Monte Carlo simulator in Ref.…”

Section: Methodsmentioning

confidence: 99%

“…The PcTK has been extensively evaluated by a Monte Carlo simulator in Ref. , while the agreement between the Monte Carlo simulator and an actual PCD has been evaluated in Ref. .…”

Section: Methodsmentioning

confidence: 99%

“…The factors included in the study were N × N sub‐pixel binning, sub‐pixel masking, and n ‐tuple‐counting. We used the Photon Counting Toolkit (PcTK) software package (pctk.jhu.edu), which was developed based on the spatio‐energetic cross‐talk model version 3.2 among PCD sub‐pixels and made available to academic researchers.…”

Section: Introductionmentioning

confidence: 99%

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Spatio‐energetic cross‐talk in photon counting detectors: N × N binning and sub‐pixel masking

et al. 2018

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Multi‐energy inter‐pixel coincidence counters for charge sharing correction and compensation in photon counting detectors

Taguchi

2020

Medical Physics

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Purpose: Smaller pixel sizes of x-ray photon counting detectors (PCDs) are advantageous for count rate capabilities but disadvantageous for charge sharing. With charge sharing, the energy of an x-ray photon may be split and one photon may produce two or more counts at adjacent pixels, both at lower energies than the incident energy. This "double-counting" increases noise variance and degrades the spectral response. Overall, it has a significantly negative impact on the performance of PCD-based computed tomography (CT). Charge sharing is induced by the detection physics and occurs regardless of count rates; thus, it is impossible to avoid. We propose in this paper a method that has a potential to address both noise and bias added by charge sharing. Methods: We propose applying a multi-energy inter-pixel coincidence counter (MEICC) technique, which uses energy-dependent coincidence counters, keeps the book of charge sharing events during data acquisition, and provides the exact number of charge sharing occurrences, which can be used to either correct or compensate for them after the acquisition is completed. MEICC does not interfere with the primary counting process; therefore, PCDs with MEICC will remain as fast as those without MEICC. MEICC can be implemented using current electronics technology because its inter-pixel coincidence counters used to handle digital data are rather simple. We evaluated Cram er-Rao lower bound (CRLB) of PCDs with and without MEICC using a Monte Carlo simulation. Results: When the number of energy windows was four or larger and eight neighboring pixels were used, the CRLBs of 225-µm PCD with MEICC normalized by those of the current PCD with the same number of windows were 0.361-0.383 for water density images of two basis functions, which was only 5.7-16.4% worse than those of a PCD without charge sharing (which were at 0.329-0.358). In contrast, the normalized CRLBs of the PCD with one coincidence counter were 0.466-0.499, which were 37.3-45.6% worse than the PCD without charge sharing. The use of eight neighboring pixels provided~10% better CRLB values than four neighboring pixels for MEICC. With four energy windows, decreasing the number of coincidence counters from 16 to 9 only slightly increased the CRLB from 0.255 to 0.269 (which corresponded to as little as a 5.5% change). The normalized CRLBs of MEICC for K-edge imaging (gold) were 0.295-0.426, while those of the one coincidence counter were 0.926-0.959 and the ideal PCDs were 0.126-0.146. Conclusions:The proposed MEICC provides spectral information that can be used to address charge sharing problems in PCDs and is expected to satisfy the requirements for clinical x-ray CT. MEICC is very effective, especially for K-edge imaging, which requires accurate spectral information.

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Spatio-energetic cross-talk in photon counting detectors: numerical detector model (PcTK) and workflow for CT image quality assessment

Cited by 16 publications

References 4 publications

Digital count summing vs analog charge summing for photon counting detectors: A performance simulation study

Digital count summing vs analog charge summing for photon counting detectors: A performance simulation study

Spatio‐energetic cross‐talk in photon counting detectors: N × N binning and sub‐pixel masking

Multi‐energy inter‐pixel coincidence counters for charge sharing correction and compensation in photon counting detectors

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