Keywords:
Calcifications / Calculi, Arteriosclerosis, Comparative studies, CT-Quantitative, CT, Cardiac
Authors:
M. Vonder1, G. J. Pelgrim1, M. Meyer2, T. Henzler2, M. Oudkerk1, R. Vliegenthart1; 1Groningen/NL, 2Mannheim/DE
Methods and Materials
A calcium insert with 100 small calcifications (size: 0.5-2.0 mm,
density: 90-540 mgHA) was placed inside a anthropomorphic thorax phantom and was scanned with third generation dual-source CT,
see Fig. 1.
The reference protocol was 120 kVp at 90 reference (ref) mAs with filtered back-projection (FBP).
The same ref mAs was used for acquisitions at 70,
80,
90,
100,
110 kVp,
reconstructed with FBP and Advanced Modeled Iterative Reconstruction (ADMIRE),
strengths 1 to 5.
These 30 protocols were compared to the reference protocol,
regarding: calcium detectability,
calcium scores and image quality.
For protocols that yielded similar calcium scores as the reference protocol,
additional scans were acquired at reduced dose by lowering the quality reference mAs in 20% steps,
to 72,
54,
36 and 18.
By adding a medium and large fat ring to the thorax phantom,
the impact of these dose reduced protocols were also evaluated for medium and large patient size.
All acquisitions were repeated five times with a small translation and rotation between each scan.
Independent-samples-median test was used to determine differences in contrast/signal to noise ratio (CNR and SNR),
dose and calcium scores.