Ralf W. Bauer MD, Presenter: Research Consultant, Siemens AG Speakers Bureau, Siemens AG

Julian Lukas Wichmann MD, Abstract Co-Author: Nothing to Disclose

Thomas Allmendinger, Abstract Co-Author: Employee, Siemens AG

Thomas Josef Vogl MD, PhD, Abstract Co-Author: Nothing to Disclose

Josef Matthias Kerl MD, Abstract Co-Author: Research Consultant, Siemens AG Speakers Bureau, Siemens AG

To investigate the impact of a novel adaptive detector collimation on dose parameters and accurateness of scan length adaption at prospectively ECG-triggered sequential cardiac CT with a new wide-detector third-generation dual-source CT.

Ideal scan lengths for human hearts were retrospectively derived from 103 triple rule out examinations. These measures were entered into the new scanner operated in prospectively ECG-triggered sequential cardiac scan mode with three different detector settings: a) adaptive detector collimation b) fixed 64 x 0.6 mm collimation c) fixed 96 x 0.6 mm collimation. Differences in effective scan length and its deviation from the ideal scan length and dose parameters (CTDIvol, DLP) for 120, 100, 90 and 70 kV were documented.

The ideal cardiac scan length could be matched by the adaptive detector collimation in every case while the mean scanned length was +15.4% with the 64 x 0.6 mm and +27.2% with the fixed 96 x 0.6 mm collimation longer. While the DLP was almost identical between the adaptive and the 64 x 0.6 mm collimation (83 vs. 89 mGycm at 120 kV), it was +62.7% and therefore significantly higher with the 96 x 0.6 mm collimation (135 mGycm).

The adaptive detector collimation for sequential acquisition allows adjusting the scan length as accurate as this can only be achieved with a spiral acquisition. This technique is further indispensable with a 57.6 mm wide detector in order to keep patient exposure low where otherwise patient dose would significantly increase with the traditional step-and-shoot mode.

A novel adaptive detector collimation ensures accurate z-axis coverage and is crucial to keep exposure parameters at the lowest level with third-generation cardiac step-and-shoot dual-source CT.

Bauer, R, Wichmann, J, Allmendinger, T, Vogl, T, Kerl, J, Evaluation of a Novel Adaptive Detector Collimation for Prospectively ECG-triggered Sequential Cardiac CT with a 192-slice Third-generation Dual-source CT.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14006367.html