Discrimination of clinically significant calcium salts using MARS spectral CT

T. E. Kirkbride, A. Raja, K. Mueller, C. J. Bateman, F. Becce, N. Anderson

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

2 Scopus citations


Calcium compounds within tissues are usually a sign of pathology, and calcium crystal type is often a pointer to the diagnosis. There are clinical advantages in being able to determine the quantity and type of calcifications non-invasively in cardiovascular, genitourinary and musculoskeletal disorders, and treatment differs depending on the crystal type and quantity. The problem arises when trying to distinguish between different calcium compounds within the same image due to their similar attenuation properties. There are spectroscopic differences between calcium salts at very low energies. As calcium oxalate and calcium hydroxyapatite can co-exist in breast and musculoskeletal pathologies of the breast, we wished to determine whether Spectral CT could distinguish between them in the same image at clinical X-ray energy ranges. Energy thresholds of 15, 22, 29 and 36keV and tube voltages of 50, 80 and 110kVp were chosen, and images were analysed to determine the percentage difference in the attenuation coefficients of calcium hydroxyapatite samples at concentrations of 54.3, 211.7, 808.5 and 1169.3mg/ml, and calcium oxalate at a concentration of 2000 mg/ml. The two lower concentrations of calcium hydroxyapatite were distinguishable from calcium oxalate at all energies and all tube voltages, whereas the ability to discriminate oxalate from hydroxyapatite at higher concentrations was dependent on the threshold energy but only mildly dependent on the tube voltage used. Spectral CT shows promise for distinguishing clinically important calcium salts.

Original languageBritish English
Title of host publicationMedical Imaging 2017
Subtitle of host publicationPhysics of Medical Imaging
EditorsTaly Gilat Schmidt, Joseph Y. Lo, Thomas G. Flohr
ISBN (Electronic)9781510607095
StatePublished - 2017
EventMedical Imaging 2017: Physics of Medical Imaging - Orlando, United States
Duration: 13 Feb 201716 Feb 2017

Publication series

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


ConferenceMedical Imaging 2017: Physics of Medical Imaging
Country/TerritoryUnited States


  • Calcium hydroxyapatite
  • Calcium oxalate
  • Spectral analysis
  • Spectral CT


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