Original articles

Cardiac imaging and non-invasive testing

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

J Rixe¹, G Conradi¹, A Rolf¹, A Schmermund², A Magedanz², D Erkapic¹, A Deetjen³, C W Hamm¹, T Dill¹

¹ Department of Cardiology, Kerckhoff Heart Centre, Bad Nauheim, Germany
² Cardioangiologisches Zentrum Bethanien, Frankfurt am Main, Germany
³ Department of Cardiology, Katharinenhospital, Stuttgart, Germany

Dr J Rixe, Department of Cardiology/Cardiovascular Imaging, Kerckhoff Heart Centre, Benekestrasse 2-8, 61231 Bad Nauheim, Germany; j.rixe{at}kerckhoff-klinik.de

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.

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