A comparative study between ultra-low dose computed tomography colonography with iterative reconstruction and low dose computed tomography colonography with filtered back projection

Abstract

Objective This study sought to evaluate and compare the radiation dose and image quality between ultra-low dose computed tomography colonography (CTC) with different levels of iterative reconstruction (Sinogram Affirmed Iterative Reconstruction, SAFIRE), and low dose CTC with filtered back projection (FBP).
Participants and Methods Following institutional ethics clearance, 80 participants who underwent screening with CTC were included. The participants were scanned using low dose protocol in a supine position with FBP, and ultra-low dose protocol in a prone position with iterative reconstruction. The effective dose and objective image quality were both evaluated.
Results The mean effective dose in low dose CTC was 1.28 mSv, compared to 0.61-0.82 mSv at four different ultra-low dose CTC (p<0.01). The mean effective dose was reduced by 46% in ultra-low dose protocol compared to low dose protocol (p<0.01). CTC image noise (standard deviation) was reduced by a maximum of 45% in CTC with iterative reconstruction compared to CTC reconstructed with SAFIRE (p<0.05).
Conclusions The radiation dose in ultra-low dose CTC with SAFIRE could be reduced by 46%, without decreasing image quality, compared to the radiation dose in low dose CTC with FBP.