Radiation dose values for various coronary calcium scoring protocols in dual-source CT

Stolzmann, Paul ; Leschka, Sebastian ; Betschart, Thomas ; Desbiolles, Lotus ; Flohr, Thomas ; Marincek, Borut ; Alkadhi, Hatem

In: The International Journal of Cardiovascular Imaging, 2009, vol. 25, no. 4, p. 443-451

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    Summary
    Purpose The purpose of this study was to assess the radiation dose and associated image noise of previously suggested calcium scoring protocols using dual-source CT. Methods One hundred consecutive patients underwent coronary calcium scoring using dual-source CT. Patients were randomly assigned to five different protocols: retrospective ECG-gating and tube current reduction to 4% outside the pulsing window at 120 (protocol A) and 100kV (B), prospective ECG-triggering at 120 (C) and 100kV (D), and prospective ECG-triggering at 100kV with attenuation-based tube current modulation (E). Radiation dose parameters and image noise were determined and compared. Results Protocol A resulted in an effective dose of 1.3±0.2mSv, protocol B in 0.8±0.2mSv, protocol C in 1.0±0.2mSv, protocol D in 0.6±0.1mSv, and protocol E in 0.7±0.1mSv. Effective doses were significantly lower (P<0.001) with 100kV when compared to 120kV protocols, and were significantly lower (P<0.001) for prospective versus retrospective ECG-gating. No significant difference was found between protocol D and E. Significant negative correlations were found between the CTDIvol and heart rate for both retrospective ECG-gating protocols (protocol A: r=−0.98, P<0.001; protocol B: r=−0.83, P<0.001). The mean image noise was 29.0±6.7HU, with no significant differences between the five protocols. The image noise was significantly correlated with the body weight (r=0.21, P<0.05) and BMI (r=0.31, P<0.01). Conclusions Effective dose of calcium scoring using dual-source CT ranges from 0.6 to 1.3mSv. Prospective triggering and lower tube voltage significantly reduces the radiation but yield similar image noise