Modeling photon-counting detectors for x-ray CT: Spectral response and pulse-pileup effects and evaluation using real data

J. Cammin, J. Xu, W. C. Barber, J. S. Iwanczyk, N. E. Hartsough, K. Taguchi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Spectral computed tomography (CT) with photon-counting detectors (PCDs) has the potential to substantially advance diagnostic CT imaging by reducing image noise and dose to the patient, by improving contrast and tissue specificity, and by enabling molecular and functional imaging. The current PCD technology, however, is limited by two main factors: imperfect energy measurement (spectral response effects, SRE) and limited count rate (pulse-pileup effects, PPE, due to detector dead-times). The overall goal of our research is to develop compensation algorithms for these sources of data distortions, to demonstrate that PCDs are suitable for clinical CT, and to identify key clinical applications for spectral CT with PCDs. We have already developed an iterative compensation scheme that includes a forward projection model of the imaging chain and that can compensate for either SRE or PPE distortions separately by maximizing a penalized log-likelihood function. In this paper we describe the evaluation of a combined, cascaded SRE and PPE model for PCDs and compare the models to data acquired with an experimental table-top PCD-CT system. The separation into count-rate independent effects (SRE) and count-rate dependent effects (PPE) allows cascading the forward model. First, the SRE model is evaluated using low count rates. Then the PPE model is cascaded and the combined SRE+PPE model is evaluated. Several different attenuators were used, including K-edge materials and the models and data were compared for various count-rate conditions.

Original languageEnglish (US)
Title of host publicationMedical Imaging 2013
Subtitle of host publicationPhysics of Medical Imaging
DOIs
StatePublished - Jun 3 2013
EventMedical Imaging 2013: Physics of Medical Imaging - Lake Buena Vista, FL, United States
Duration: Feb 11 2013Feb 14 2013

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume8668
ISSN (Print)1605-7422

Other

OtherMedical Imaging 2013: Physics of Medical Imaging
CountryUnited States
CityLake Buena Vista, FL
Period2/11/132/14/13

Keywords

  • Computed tomography
  • Photon-counting detectors
  • Pulse-pileup
  • Spectral response

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging

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