Low kilovoltage cardiac dual-source CT: attenuation, noise, and radiation dose

Leschka, Sebastian ; Stolzmann, Paul ; Schmid, Florian ; Scheffel, Hans ; Stinn, Bjoern ; Marincek, Borut ; Alkadhi, Hatem ; Wildermuth, Simon

In: European Radiology, 2008, vol. 18, no. 9, p. 1809-1817

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    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 (120kV/330mAs), 20 were examined at 100kV/330mAs, and 20 at 100kV/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 100kV/330mAs (26 ± 3HU, 549 ± 62HU, 25.5 ± 3.2; each P < 0.01) and 100kV/220mAs (27 ± 2HU, 560 ± 43HU, 25.0 ± 2.2; each P < 0.01) when compared to the 120-kV protocol (21 ± 2HU, 317 ± 28HU, 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 ± 1.2mSv) was significantly higher than the 100kV/330mAs (6.7 ± 0.8mSv, P < 0.01) or 100kV/220mAs (4.4 ± 0.6mSv, P < 0.001) protocols. Dual-source CTCA with 100kV 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