Abstract
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 language | English (US) |
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Pages (from-to) | 159-165 |
Number of pages | 7 |
Journal | Radiology |
Volume | 196 |
Issue number | 1 |
DOIs | |
State | Published - Jul 1995 |
Keywords
- Computed tomography (CT), electron beam
- Computed tomography (CT), physics
- Coronary vessels, calcification
- Phantoms
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging