Heart: Dual-source CT shows promise in reducing radiation dose

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When standard protocols for coronary CT angiography with 16-, 64-slice multidetector CT and dual-source CT scanners are used, the radiation dose is still high; however, imagers can achieve low estimated radiation doses when using optimized and individually adjusted protocols, according to a study in the August issue of Heart.

J. Rixe, MD, from the department of cardiology at Kerckhoff Heart Centre in Bad Nauheim, Germany, and colleagues compared radiation dose estimates of dual-source CT with 16- and 64-slice multidetector CT for coronary angiography. They performed a retrospective data analysis on 292 patients, examining 56 patients with 16-slice multidetector CT, 38 patients with 64-slice multidetector CT and 202 patients using dual-source CT.

The investigators calculated the effective dose estimates for all patients from the dose–length product and the conversion factor k (0.017 mSv/mGy/cm), as recommended by current guidelines.

Researchers reported that the mean effective dose for patients examined by 16-slice MDCT was 9.8 mSv, for 64-slice multidetector CT 8.6 mSv and for dual-source CT 11.4 mSv. With a protocol of 100 kV tube voltage and 110 mAs ECG-pulsing window, the mean effective dose was 3.8 mSv for dual-source CT scanning.

Rixe and colleagues found that dual-source CT with a tube voltage of 100 kV resulted in a significant inverse correlation between heart rate and radiation dose exposure.

Based on their findings, the authors concluded that “dual-source CT has the potential to reduce radiation dose exposure, if the scan protocol is adjusted appropriately.

“Dose optimization thus remains a highly important concern that must be dealt with by cardiologists, radiologists and manufacturers of multidetector CT scanners," they added.