Keywords:
Diagnostic procedure, CT, Cardiac, Dosimetry, Dosimetric comparison
Authors:
B. Petritsch1, T. Allmendinger2, A. Kunz1, T. A. Bley1, T. Gassenmaier1; 1Würzburg/DE, 2Forchheim/DE
Methods and Materials
Phantom
The study was performed with a commercially available 30-cm-wide anthropomorphic calcium scoring phantom (QRM,
Moehrendorf,
Germany) with a total of six cylindrical inserts (3 inserts of 5 mm and 3 inserts of 3 mm) containing hydroxyapatite at different concentrations (800; 400; 200 mg/cm3).
Each acquisition was conducted three times,
i.e.
without additional attenuation ring,
as well as with small and large attenuation rings for simulation of a slim,
average-sized and large patient.
CT scanner & image reconstruction
All scans were performed with a third-generation dual-source CT (SOMATOM Force,
Siemens,
Forchheim,
Germany) at 120 kVp tube potential.
Tube current was set to 80mAs for reference and then stepwise reduced to 60,
40,
20 and 10 mAs,
respectively.
Images were reconstructed with a standard weighted filtered back projection (wFBP) kernel.
Additional reconstructions were performed with a new version of an established iterative reconstruction kernel (ADMIRE) at different strength levels,
ranging from 1 (lowest) to 5 (highest).
For each series,
calcifications were quantified by calculation of Agatston scores.
Statistical Analysis
Comparison between FBP and the different strength levels of the new ADMIRE reconstruction algorithm was performed with the Kruskal-Wallis-test and the Mann-Whitney-U-test for between-group comparisons.