Radiation Dose Exposure of Computed Tomography Coronary Angiography - Comparison of Dual Source -, 16 – slice and 64 – slice - CT

Johannes Rixe ^1*, Guido Conradi ¹, Andreas Rolf ¹, Axel Schmermund ², Annett Magedanz ², Damir Erkapic ¹, Anja Deetjen ³, Christian W Hamm ¹ and Thorsten Dill ¹

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

^* To whom correspondence should be addressed. E-mail: j.rixe{at}kerckhoff-klinik.de.

Accepted 24 March 2009

Abstract

Objective: 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. The aim of this study was to compare radiation dose estimates of DSCT to 16 - and 64 - slice multi detector CT (MDCT) for non - invasive coronary angiography.

Patients and design: Retrospective data analysis was performed on 292 patients: 56 patients examined with 16 - slice MDCT, 34 patients with 64 - slice MDCT and 202 patients using DSCT. The effective dose estimates (ED) were calculated for all patients from the dose length product (DLP) and the conversion factor k (0.017 mSv x mGy-1 x cm-1), as recommended by current guidelines.

Results: The mean ED for patients examined by 16 - slice MDCT was 9.76 ± 1.84 mSv, for 64 - slice MDCT 7.9 ± 1.6 mSv, and for DSCT 11.36 ± 7.2 mSv, respectively. With a protocol of 100 kV tube voltage and 110 ms ECG pulsing- window the mean ED was 3.75 ± 1.68 mSv for DSCT scanning. Using DSCT with a tube voltage of 100 kV, there was a significant inverse correlation between heart rate and radiation dose exposure.

Conclusions: Using standard protocols for coronary CT – angiography with 16 -, 64 – slice – and DSCT – scanners, radiation dose is still high. However, using optimized and individually adjusted protocols low estimated radiation doses can be achieved.