RSNA 2012 

Abstract Archives of the RSNA, 2012


SSQ18-07

Assessment of Image Quality with Filtered Back Projection and Iterative Reconstruction Technique (ASiR ) for Low Dose and Ultra Low Dose in an Anthropomorphic Phantom

Scientific Formal (Paper) Presentations

Presented on November 29, 2012
Presented as part of SSQ18: Physics (CT Reconstruction)

Participants

Gaurav Shyam Desai MBBS, Presenter: Nothing to Disclose
Avinash R. Kambadakone MD, FRCR, Abstract Co-Author: Nothing to Disclose
Dushyant V. Sahani MD, Abstract Co-Author: Research collaboration, General Electric Company Consultant, Bracco Group
Michael Ethan Zalis MD, Abstract Co-Author: Nothing to Disclose

PURPOSE

To compare the performance of low dose (LD) and ultra-low dose (ULD) scan protocols and image quality in an anthropomorphic colon phantom study reconstructed using Filtered Back Projection (FBP), Adaptive Statistical Iterative Reconstruction (ASiR).

METHOD AND MATERIALS

A colon phantom (with 11 polyps, mean polyp size 1.12+/-0.2 cm) was scanned on a CT system equipped with ASiR technology (GE 64). For ASiR, the phantom was scanned at a kV/mAs combinations in 3 groups; A1=120 /35-25-15, A2=100/50-35, and A3=80/50-25 (2.5-mm, 64 × 0.625 mm). Images were reconstructed using FBP and ASiR 30 and 60. Two blinded readers evaluated images for quality acceptable for rendering colonic and extra-colonic interpretations. The objective noise, polyp measurment and dose in CTDivol were recorded.

RESULTS

All examinations except for those scanned at kV/ mAs of 80/25 were acceptable with FBP and ASiR image reconstruction methods. There was no change in polyp size with the different scanner settings. ASiR improved image quality in all subgroups including scans taken at 80kV and 25 mAs. CTDivol recorded was highest for 120kV/35mAs: 2.04 mGy and lowest for 80kV/25mAs: 0.49mGy. Objective noise was lowest for images acquired with (ASiR 30 and 60) and FBP for G1 (24.2, 20.2, 29.3) and most for G3 (46.5, 48.2, 67) CTDivol recorded was highest for 120kV/70mA: 2.04 mGy and lowest for 80kV/50mA: 0.49mGy.

CONCLUSION

Iterative reconstruction with ASiR provide diagnostic quality for interpreting colonic and extra colonic findings in an anthroprometric phantom at a fraction dose of currently used low dose CT protocol.

CLINICAL RELEVANCE/APPLICATION

CT Colonography (CTC) is a screening examination in healthy adults. Iterative reconstruction techniques have potential advantages in improving image quality and reducing radiation levels.

Cite This Abstract

Desai, G, Kambadakone, A, Sahani, D, Zalis, M, Assessment of Image Quality with Filtered Back Projection and Iterative Reconstruction Technique (ASiR ) for Low Dose and Ultra Low Dose in an Anthropomorphic Phantom.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12037765.html