, Volume 18, Issue 3, pp 592-599
Date: 02 Oct 2007

Radiation dose estimates in dual-source computed tomography coronary angiography

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Abstract

The purpose of this study was to quantify radiation dose parameters of dual-source CT coronary angiography. Eighty patients underwent contrast-enhanced, retrospectively ECG-gated dual-source CT coronary angiography with heart rate-adapted ECG pulsing using two algorithms: In 40 patients, the tube current was reduced to 20% (Amin1) of the normal tube current (Amax) outside the pulsing window; in 40 patients tube current was reduced to 4% (Amin2) of Amax. Mean CTDIvol in the Amin1 group was 45.1 ± 3.6 mGy; the mean CTDIvol in the Amin2 group was 39.1 ± 3.2 mGy, with CTDIvol in the Amin2 group being significantly reduced when compared to the Amin1 group (P < 0.001). A significant negative correlation was found between CTDIvol and heart rate in group Amin1 (r = −0.82, P < 0.001), whereas no correlation was found between CTDIvol and heart rate in group Amin2 (r = −0.066). Using the conversion coefficient for the chest, dual-source CT coronary angiography resulted in an estimated mean effective dose of 8.8 mSv in the Amin1 group and 7.8 mSv in the Amin2. Radiation exposure of dual-source CT coronary angiography using an ECG-pulsing protocol reducing the tube current to 20% significantly decreases with increasing heart rates, despite using wider pulsing windows at higher heart rates. When using a protocol with reduced tube current of 4%, the radiation dose is significantly lower, irrespective of the heart rate.