Electron-beam CT: Use of a calibration phantom to reduce variability in calcium quantitation

Cynthia H. McCollough, Rachel B. Kaufmann, Bruce M. Cameron, Dolores J. Katz, Patrick F. Sheedy, Patricia A. Peyser

Research output: Contribution to journalArticlepeer-review

67 Scopus citations


PURPOSE: To measure scanner and patient variation in computed tomographic (CT) numbers for electron-beam CT and to determine the ability of calibration phantoms to reduce variability in calcium quantitation. MATERIALS AND METHODS: Two calibration phantoms were imaged to ensure longitudinal homogeneity and to determine the short-term intrascanner variation in CT numbers. Each phantom set was imaged twice a day for 14 weeks to determine intra- and interscanner variation. Data from examinations of 167 patients that included the phantom were analyzed to determine the intra- and interpatient variation in CT numbers of objects with known calcium concentrations. RESULTS: The calibration reduced scanner variations by approximately 25%. The calcium concentration associated with a CT number of 130 HU varied from 77.1 to 136.4 mg/cm3 and was dependent on patient girth, sex, smoking history, and image level. CONCLUSION: Scanner and patient variations in CT numbers in electron-beam CT can be reduced with a calibration phantom. In vitro and in vivo estimates of calcium concentration had a precision of 2% and 7%, respectively.

Original languageEnglish (US)
Pages (from-to)159-165
Number of pages7
Issue number1
StatePublished - Jul 1995


  • Computed tomography (CT), electron beam
  • Computed tomography (CT), physics
  • Coronary vessels, calcification
  • Phantoms

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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