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 compared to the reference protocol,
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<p<0.206).
For the 100kVp-IR1 protocol with 52-74 ref mAs,
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%.