Material separation in x-ray CT with energy resolved photon-counting detectors

X. Wang, D. Meier, K. Taguchi, D. J. Wagenaar, B. E. Patt, E. C. Frey

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

1 Scopus citations


The objective of the study was to demonstrate that more than two types of materials can be effectively separated with x-ray CT using a recently developed energy resolved photon-counting detector. We performed simulations and physical experiments using an energy resolved photon-counting detector with six energy thresholds. For comparison, dual-kVp CT with an integrating detector was also simulated. Iodine- and gadolinium-based contrast agents, as well as several soft-tissue- and bone-like materials were imaged. We plotted the attenuation coefficients for the various materials in a scatter plot for pairs of energy windows. In both simulations and physical experiments, the contrast agents were easily separable from other non-contrast-agent materials in the scatter plot between two properly chosen energy windows. This separation was due to discontinuities in the attenuation coefficient around their unique K-edges. The availability of more than two energy thresholds in a photon-counting detector allowed the separation with one or more contrast agents present. Compared with dual-kVp methods, CT with an energy resolved photon-counting detector provided a larger separation and the freedom to use different energy window pairs to specify the desired target material. We concluded that an energy resolved photon-counting detector with more than two thresholds allowed the separation of more than two types of materials, e.g., soft-tissue-like, bone-like, and one or more materials with K-edges in the energy range of interest. They provided advantages over dual-kVp CT in terms of the degree of separation and the number of materials that can be separated simultaneously.

Original languageEnglish (US)
Title of host publicationMedical Imaging 2011
Subtitle of host publicationPhysics of Medical Imaging
StatePublished - May 13 2011
EventMedical Imaging 2011: Physics of Medical Imaging - Lake Buena Vista, FL, United States
Duration: Feb 13 2011Feb 17 2011

Publication series

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


OtherMedical Imaging 2011: Physics of Medical Imaging
Country/TerritoryUnited States
CityLake Buena Vista, FL


  • CT
  • energy resolved photon-counting detector
  • material separation
  • spectral CT

ASJC Scopus subject areas

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


Dive into the research topics of 'Material separation in x-ray CT with energy resolved photon-counting detectors'. Together they form a unique fingerprint.

Cite this