Radiation dose exposure of computed tomography coronary angiography: comparison of dual-source, 16-slice and 64-slice CT

Background: Dual-source CT (DSCT) promises a significant reduction of radiation dose exposure for coronary CT angiography (CTA). Large studies on radiation dose estimates are rare. Objective: To compare radiation dose estimates of DSCT with 16- and 64-slice multidetector CT (MDCT) for non-invasive coronary angiography. Patients and design: Retrospective data analysis was performed on 292 patients: 56 patients were examined with 16- slice MDCT, 38 patients with 64-slice MDCT and 202 patients using DSCT. The effective dose (ED) estimates were calculated for all patients from the dose length product and the conversion factor k (0.017 mSv/mGy/cm), as recommended by current guidelines. Results: The mean (SD) ED for patients examined by 16-slice MDCT was 9.8 (1.8) mSv, for 64-slice MDCT 8.6 (2.8) mSv and for DSCT 11.4 (7.2) mSv. With a protocol of 100 kV tube voltage and 110 ms ECG pulsing window the mean (SD) ED was 3.8 (1.7) mSv for DSCT scanning. When DSCT with a tube voltage of 100 kV was used, a significant inverse correlation between heart rate and radiation dose exposure was found. Conclusions: When standard protocols for coronary CTA with 16-, 64-slice MDCT and DSCT scanners are used, the radiation dose is still high. However, using optimised and individually adjusted protocols low estimated radiation doses can be achieved.