Image Quality Assessment in Torso Phantom Comparing Effects of Varying Automatic Current Modulation with Filtered Back Projection,Adaptive Statistical,and Model-Based Iterative Reconstruction Techniques in CT

ObjectivesTo compare image quality on computed tomographic (CT) images acquired with different levels of automatic tube current modulation reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and novel model-based iterative reconstruction (MBIR) techniques.MethodsA torso phantom was scanned at 17 different noise levels of automatic current modulation and images were reconstructed with FBP, ASIR, and MBIR. Objective and subjective image qualities were assessed. Effective dose was also calculated.ResultsObjective image analysis supports significant noise reduction and superior contrast to noise ratio with new a MBIR technique. Subjective image parameters were maximally rated for MBIR followed by ASIR then FBP. The reconstruction algorithms were evaluated over effective doses ranging from 0.7 to 3 mSv.ConclusionMBIR shows superior reduction in noise and improved image quality (both objective and subjective analysis) compared with ASIR and FBP. It was possible to achieve meaningful image quality even at the highest noise index of 70 achieving substantial dose reduction to as low as 0.7 mSv.