Stefan Baumann MD, Abstract Co-Author: Nothing to Disclose

Felix G. Meinel MD, Presenter: Nothing to Disclose

Christian Canstein, Abstract Co-Author: Employee, Siemens AG

Martin Ulrich Sedlmair MS, Abstract Co-Author: Employee, Siemens AG

Carlo Nicola de Cecco MD, Abstract Co-Author: Nothing to Disclose

U. Joseph Schoepf MD, Abstract Co-Author: Research Grant, Bracco Group Research Grant, Bayer AG Research Grant, General Electric Company Research Grant, Siemens AG

Bernhard Schmidt PhD, Abstract Co-Author: Employee, Siemens AG

Brett S. Harris PhD, Abstract Co-Author: Nothing to Disclose

Thomas G. Flohr PhD, Abstract Co-Author: Employee, Siemens AG

To assess the influence of tube potential on radiation dose and image quality at 3rd generation dual-source coronary CT angiography (CTA) in a phantom model simulating an obese patient.

A thoracic phantom was equipped with tubular inserts containing iodine solution and water. A soft tissue-equivalent ring around the phantom simulated an obese patient. Images were acquired at tube potentials of 80, 100, 120, and 140 kV with 2nd generation dual-source CT (DSCT) and 70–150 kV (in 10 kV increments) with 3rd generation DSCT. Contrast-to-noise ratio (CNR) was calculated and CT dose index was recorded.

With 2nd generation DSCT, iodine attenuation decreased from 667 ± 4 HU at 80 kV to 315 ± 3 HU at 140 kV and image noise decreased from 56 ± 4 HU at 80 kV to 18 ± 1 HU at 140 kV. With 2nd generation DSCT, CNR was highest for 120 kV (19.0) and decreased with lower tube potential (12.0 at 80 kV) due to disproportionately increased image noise. With 3rd generation DSCT, iodine attenuation decreased from 782 ± 9 HU at 70 kV to 309 ± 4 HU at 150 kV and image noise decreased from 37 ± 4 HU at 70 kV to 17 ± 2 HU at 150 kV. With 3rd generation DSCT, 70 and 80 kV acquisitions showed a smaller increase in noise. CNRs for 3rd generation DSCT were highest for 70 and 80 kV (21.1 and 21.2, respectively). Compared to 120 kV, radiation dose was 68 % and 49 % lower at 70 kV and 80 kV, respectively.  

Our phantom experiments indicate that the high tube power of 3rd generation DSCT can prevent the disproportionate increase in image noise, which has so far precluded the use of low tube potential CTA in obese patients. Third generation DSCT may enable performing coronary CTA at 70-80 kV in obese patients without compromising subjective and objective image quality. Compared to 120 kV, which is the currently the clinical standard for obese patients, this approach reduces radiation dose by 49-68 %.

Third generation DSCT offers substantially increased tube power at low tube potential, which may enable performing coronary CT angiography at 70-80kV in obese patients and can reduce radiation dose by 49-68%.

Baumann, S, Meinel, F, Canstein, C, Sedlmair, M, de Cecco, C, Schoepf, U, Schmidt, B, Harris, B, Flohr, T, Image Quality and Radiation Dose of Low Tube Voltage Third Generation Dual-Source Coronary CT Angiography in Obese Patients: A Phantom Study.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14010853.html