DOI: 10.1148/radiol.2253011871
Coronary Artery Calcium Measurement with Multi–Detector Row CT: In Vitro Assessment of Effect of Radiation Dose1
Cheng Hong, MD, PhD,
Kyongtae T. Bae, MD, PhD,
Thomas K. Pilgram, PhD,
Jongdae Suh, MD and
David Bradley, BS, RT
1 From the Mallinckrodt Institute of Radiology, Washington University School of Medicine, Campus Box 8131, 510 S Kingshighway Blvd, St Louis, MO 63110 (C.H., K.T.B., T.K.P., J.S.); and Siemens Medical Systems, Iselin, NJ (D.B.). Received November 25, 2001; revision requested February 4, 2002; final revision received May 3; accepted May 29. Address correspondence to K.T.B. (e-mail: baet@mir.wustl.edu).
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Figure 1. Anthropomorphic cardiac phantom with the calibration inserts. HA = hydroxyapatite.
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Figure 2. Plot shows relationship between tube current and image noise. As tube current increased, image noise decreased in a consistent fashion (r = 0.90, P = .002).
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Figure 3. Representative multi-detector row CT scans of calcified cylinders in the phantom were obtained at (left) 20, (middle) 100, and (right) 160 mAs. The image obtained at 20 mAs shows the most noise.
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Figure 4. Plot shows relationship between tube current and calcium volume error expressed as a percentage of the true value. There appears to be no relationship between the tube current and calcium volume error (r = 0.03, P = .82). Size of data points indicates size of lesion: small = 3-mm diameter, large = 5-mm diameter. Color of data points indicates calcium density: white = 200 mg/cm3, gray = 400 mg/cm3, and black = 800 mg/cm3.
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Figure 5. Plot shows relationship between tube current and calcium mass error expressed as a percentage of the true value. There appears to be no relationship between the tube current and calcium mass error (r = 0.06, P = .70). Size of data points indicates size of lesion: small = 3-mm diameter, large = 5-mm diameter. Color of data points indicates calcium density: white = 200 mg/cm3, gray = 400 mg/cm3, black = 800 mg/cm3.
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Figure 6. Plot shows relationship between CaHA density and calcium volume error expressed as a percentage of the true value: small circles = individual values, large circles = means, and error bars = 1 SD. There is a clear tendency for the calcium volume error to be larger with larger CaHA densities. Differences between the means of the errors are statistically significant (P < .001).
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Figure 7. Plot shows relationship between CaHA density and calcium mass error expressed as a percentage of the true value: small circles = individual values, large circles = means, and error bars = 1 SD. There is a clear tendency for the calcium mass error to be smaller with larger CaHA densities. Differences between the means of the errors are statistically significant (P < .001).
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Figure 8. Plot shows relationship between calcium volume and mass errors expressed as a percentage of the true value. There is a clear relationship between the relative size of the errors, though the calcium volume error has a much larger range than that of the calcium mass error (r = 0.90, P < .001). The data points are clustered in terms of CaHA density, as noted in Figures 6 and 7. Size of data points indicates size of lesion: small = 3-mm diameter, large = 5-mm diameter. Color of data points indicates calcium density: white = 200 mg/cm3, gray = 400 mg/cm3, black = 800 mg/cm3.
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Copyright © 2002 by the Radiological Society of North America.
