Coronary CTA with lower tube voltage reduces radiation exposure


NEW YORK (Reuters Health), Apr 27 - A coronary CT angiography (CTA) protocol with reduced tube voltage results in a significant reduction in radiation exposure, and image quality in nonobese patients is not compromised, according to findings published in the April issue of the American Journal of Roentgenology.

"Despite its noninvasive nature, the associated radiation exposure of coronary CT angiography has been reason for concern," write Dr. Tobias Pflederer and colleagues from the University of Erlangen, Germany.

The researchers assessed image quality of coronary dual-source CT angiography in 100 consecutive patients with a body weight < 85 kg who were randomly assigned to either scanning protocol 1, which used a tube voltage of 120 kV and a tube current-time product of 330 mAs, or to group 2, which reduced the tube voltage to 100 kV.

Two independent observers assessed datasets for image quality. The effective dose was estimated using the dose-length product.

The mean estimated effective radiation dose was significantly reduced from 12.7 mSv in group 1 to 7.8 mSv in group 2 (p < 0.001). This corresponded to a reduction of radiation exposure of 38.6%.

The investigators report that the overall image quality was preserved. The mean quality image score was 2.7 in group 1 and 2.6 in group 2 (p = 0.75).

Group 1 included one nonassessable patient and two nonassessable vessels, and group 2 had two nonassessable patients and three nonassessable vessels. The team notes that overall interobserver agreement in assessing image quality was good.

Still, they recommend that other methods of reducing the radiation dose further should be explored, including the technique of prospective rather than retrospective gating and a reduction of tube current during ECG dose modulation.

Am J Roentgenol 2009;192:1045-1050.

Last Updated: 2009-04-24 15:00:24 -0400 (Reuters Health)

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