Iterative reconstruction reduces abdominal CT dose
Anne Catrine Trægde Martinsen1, Hilde Kjernlie Sæther, Per Kristian Hol
1The Intervention Centre, Oslo University Hospital, Rikshospitalet, Postboks 4950 Nydalen, N-0424 Oslo, Norway. anne.catrine.martinsem@ous-hf.no
Objective:
In medical imaging, lowering radiation dose from computed tomography scanning, without reducing diagnostic performance is a desired achievement. Iterative image reconstruction may be one tool to achieve dose reduction. This study reports the diagnostic performance using a blending of 50% statistical iterative reconstruction (ASIR) and filtered back projection reconstruction (FBP) compared to standard FBP image reconstruction at different dose levels for liver phantom examinations.
Methods:
An anthropomorphic liver phantom was scanned at 250, 185, 155, 140, 120 and 100 mAs, on a 64-slice GE Lightspeed VCT scanner. All scans were reconstructed with ASIR and FBP. Four readers evaluated independently on a 5-point scale 21 images, each containing 32 test sectors. In total 672 areas were assessed. ROC analysis was used to evaluate the differences.
Results:
There was a difference in AUC between the 250 mAs FBP images and the 120 and 100 mAs FBP images. ASIR reconstruction gave a significantly higher diagnostic performance compared to standard reconstruction at 100 mAs.
Conclusion:
A blending of 50-90% ASIR and FBP may improve image quality of low dose CT examinations of the liver, and thus give a potential for reducing radiation dose.
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