Clinical evaluation of automatic tube voltage selection in chest CT angiography
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To evaluate the clinical impact of automatic tube voltage selection on chest CT angiography (CTA).
Ninety-three patients were prospectively evaluated with a CT protocol aimed at comparing two successive CTAs acquired under similar technical conditions except for the kV selection: (1) the initial CTA was systematically obtained at 120 kVp and 90 ref mAs; (2) the follow-up CTA was obtained with an automatic selection of the kilovoltage (Care KV; Siemens Healthcare) for optimised CTA.
At follow-up, 90 patients (97 %) underwent CTA with reduced tube voltage, 100 kV (n = 26; 28 %) and 80 kV (n = 64; 69 %), resulting in a significant dose-length-product reduction (follow-up: 87.27; initial: 141.88 mGy.cm; P < 0.0001; mean dose reduction: 38.5 %) and a significant increase in the CNR at follow-up (follow-up: 11.5 ± 3.5 HU; initial: 10.9 ± 3.7 HU; P = 0.03). The increase in objective image noise at follow-up (follow-up: 23.2 ± 6.7 HU vs. 17.8 ± 5.1 HU; P < 0.0001) did not alter the diagnostic value of images.
Automatic tube voltage selection reduced the radiation dose delivered during chest CT angiograms by 38.5 % while improving the contrast-to-noise ratio of the examinations.
• As low a dose as possible must be used for CT angiography.
• Automatic tube voltage selection permits reduced patient exposure.
• Lowering the kVp enables increased intravascular attenuation.
• Automatic tube voltage selection does not compromise the overall image quality.
KeywordsCT angiography Dose Image quality kV/kVp Tube voltage
T. Niemann received grants from the Cancer League of Basel City and Basel Country and the Gottfried and Julia Bangerter-Rhyner Foundation.
T. Flohr is an employee of Siemens Medical Systems. J. Remy is consultant for Siemens Medical Systems.
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