Exploration of the pulse pileup effects in a clinical CdTe-based photon-counting computed tomography.
ACR phantom
CT number
Poisson statistics
computed tomography
contrast-to-noise ratio (CNR)
flux
modulation transfer function (MTF)
noise power spectrum (NPS)
photon counting CT
pulse pileup
Journal
Medical physics
ISSN: 2473-4209
Titre abrégé: Med Phys
Pays: United States
ID NLM: 0425746
Informations de publication
Date de publication:
Nov 2023
Nov 2023
Historique:
revised:
27
06
2023
received:
20
01
2023
accepted:
20
07
2023
medline:
6
11
2023
pubmed:
21
8
2023
entrez:
21
8
2023
Statut:
ppublish
Résumé
High tube current generates a high flux of x-rays to photon counting detectors (PCDs) that can potentially result in the piling up of pulses formed by concurrent photons, which can cause count loss and energy resolution degradation. To evaluate the performance of clinical photon-counting CT (PCCT) systems in high flux, potentially influenced by pulse pileup effects, in terms of task-generic image quality metrics. A clinical phantom was scanned on a commercial PCCT scanner (NAEOTOM Alpha, Siemens) at 120 kV under fourteen different tube current levels (40-1000 mA) with a rotation time of 0.25 s and a pitch of 1. The dose levels corresponded to CTDI The 50% cut-off frequency of TTF (f Increasing tube currents did not affect the spatial resolution, but slightly affected the CT number and noise measurements of the clinical PCCT system. However, the effects were only considerable at clinically irrelevant tube currents used on a small 20-cm phantom. In general clinical practices, automatic exposure control techniques are used to decrease the variation of flux on the detector, which alleviates the chances of detector saturation due to high count rates. The observed effects could be due to pulse pileup, signal-dependent filtration of the system, or nonlinearities in the reconstruction algorithm. In conclusion, either the deadtime of the detector used in the photon-counting CT system is shorter such that count losses due to pulse pileup are negligible, or pulse pileup has inconsiderable effects on the image quality of clinical photon-counting CT systems in routine clinical practice due to possible corrections applied on the system.
Sections du résumé
BACKGROUND
BACKGROUND
High tube current generates a high flux of x-rays to photon counting detectors (PCDs) that can potentially result in the piling up of pulses formed by concurrent photons, which can cause count loss and energy resolution degradation.
PURPOSE
OBJECTIVE
To evaluate the performance of clinical photon-counting CT (PCCT) systems in high flux, potentially influenced by pulse pileup effects, in terms of task-generic image quality metrics.
METHODS
METHODS
A clinical phantom was scanned on a commercial PCCT scanner (NAEOTOM Alpha, Siemens) at 120 kV under fourteen different tube current levels (40-1000 mA) with a rotation time of 0.25 s and a pitch of 1. The dose levels corresponded to CTDI
RESULTS
RESULTS
The 50% cut-off frequency of TTF (f
CONCLUSIONS
CONCLUSIONS
Increasing tube currents did not affect the spatial resolution, but slightly affected the CT number and noise measurements of the clinical PCCT system. However, the effects were only considerable at clinically irrelevant tube currents used on a small 20-cm phantom. In general clinical practices, automatic exposure control techniques are used to decrease the variation of flux on the detector, which alleviates the chances of detector saturation due to high count rates. The observed effects could be due to pulse pileup, signal-dependent filtration of the system, or nonlinearities in the reconstruction algorithm. In conclusion, either the deadtime of the detector used in the photon-counting CT system is shorter such that count losses due to pulse pileup are negligible, or pulse pileup has inconsiderable effects on the image quality of clinical photon-counting CT systems in routine clinical practice due to possible corrections applied on the system.
Substances chimiques
cadmium telluride
STG188WO13
Cadmium Compounds
0
Tellurium
NQA0O090ZJ
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Pagination
6693-6703Subventions
Organisme : NIH HHS
ID : R01EB001838
Pays : United States
Organisme : NIH HHS
ID : R01HL155293
Pays : United States
Organisme : NIH HHS
ID : P41EB028744
Pays : United States
Informations de copyright
© 2023 American Association of Physicists in Medicine.
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