Low kilovoltage cardiac dual-source CT: attenuation, noise, and radiation dose
The purpose of this study was to investigate the effect of low kilovoltage dual-source computed tomography coronary angiography (CTCA) on qualitative and quantitative image quality parameters and radiation dose.
Dual-source CTCA with retrospective ECG gating was performed in 80 consecutive patients of normal weight. Forty were examined with a standard protocol (120 kV/330mAs), 20 were examined at 100 kV/330mAs, and 20 at 100 kV/220mAs. Two blinded observers independently assessed image quality of each coronary segment and measured the image parameters noise, attenuation, and contrast-to-noise ratio (CNR). The effective radiation dose was calculated using CT dose volume index and the dose-length product.
Diagnostic image quality was obtained in 99 % of all coronary segments (1,127/1,140) without significant differences among the protocols. Image noise, attenuation, and CNR were significantly higher for 100 kV/330mAs (26±3 HU, 549± 62 HU, 25.5±3.2; each P<0.01) and 100 kV/220mAs (27±2 HU, 560± 43 HU, 25.0±2.2; each P<0.01) when compared to the 120-kV protocol (21±2 HU, 317±28 HU, 20.6±1.7). There was no significant difference between the two 100-kV protocols. Estimated effective radiation dose of the 120-kV protocol (8.9±1.2 mSv) was significantly higher than the 100 kV/330mAs (6.7±0.8 mSv, P<0.01) or 100 kV/220mAs (4.4± 0.6 mSv, P<0.001) protocols.
Dual-source CTCA with 100 kV is feasible in patients of normal weight, results in a diagnostic image quality with a higher CNR, and at the same time significantly reduces the radiation dose.
Authors: Sebastian Leschka, Paul Stolzmann, Florian T. Schmid, Hans Scheffel, Bjoern Stinn, Borut Marincek, Hatem Alkadhi, Simon Wildermuth
Full text available on: Eur Radiol 2008 Sep;18(9):1809-17. Epub 2008 Apr 8.
