Effective atomic number and electron density determination using spectral X-ray CT

Matteo Busi*, Jan Kehres, Mohamad Khalil, Ulrik Lund Olsen

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

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We present Spectral X-ray Computed Tomography (SCT) estimations of material properties directly from energy-dependent measurements of linear attenuation coefficients (LAC). X-ray Computed Tomography (CT) is commonly utilized to characterize the internal properties of an object of interest. Dual-Energy X-ray CT allows material characterization into energy-independent physical properties such as Ze and electron density ρe. However, it is not robust in presence of dense materials and metal artifacts. We report on the performance of a method for system-independent characterization of materials that introduces a spectroscopic detector into X-ray CT, called spectral ρe/Ze estimation (SRZE). We benchmark the SRZE method against energy-integrated measurements in material classification tests, finding superior accuracy in the predictions. The advantage of this technique, over other methods for material characterization using x-ray CT, is that it does not require a set of reference materials for calibration. Moreover, the simultaneous detection of spectral features makes it robust to highly attenuating materials, since the energy intervals for which the attenuation is photon limited can easily be detected and excluded from the feature estimation.
Original languageEnglish
Title of host publicationAnomaly Detection and Imaging with X-Rays (ADIX) IV
EditorsAmit Ashok , Joel A. Greenburg , Michael E. Gehm
Number of pages11
PublisherSPIE - International Society for Optical Engineering
Publication date2019
Article number1099903
Publication statusPublished - 2019
EventSPIE Defense + Commercial Sensing 2019 - Baltimore, United States
Duration: 14 Apr 201918 Apr 2019


ConferenceSPIE Defense + Commercial Sensing 2019
Country/TerritoryUnited States
SeriesProceedings of SPIE - The International Society for Optical Engineering


  • Spectral X-ray CT
  • X-ray characterization
  • Effective atomic number
  • Electron density
  • MULTIX-ME100
  • Therat detection
  • Security screening


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