To define a low-dose coronary calcium scan protocol including advanced dose reduction techniques yielding similar calcium score results as the conventional full-dose protocol.
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,
reconstructed with FBP and Advanced Modeled Iterative Reconstruction (ADMIRE),
strengths 1 to 5.
These 30 protocols were...
Of the 30 protocols compared to the reference protocol,
only 90kVp-ADMIRE3 and 100kVp-ADMIRE1 did not show any difference in detectability,
volume score and mass score (p>0.206).
Detectability and Agatston score were not affected by lower tube currents of 36-72 ref mAs with 90kVp-ADMIRE3 and 54-72 ref mAs with 100kVp-ADMIRE1 for small to large patient size (p>0.206),
see Fig. 2 ,
while the and CNR and SNR were similar or higher than the reference protocol (0.008
In this experiment,
out of the 30 protocols,
the combination of 90 kVp with ADMIRE strength 3 or 100 kVp with ADMIRE strength 1 yielded similar calcium detectability,
Agatston score and image quality as conventional 120 kVp with FBP,
with dose reduction up to 60.6%.