Abstract
Purpose: To investigate the effect of Model-Based Iterative Reconstruction (MBIR) on CT#s and noise (standard deviation, SD) of both nodules and homogeneous regions (heart and vertebra spongiosa) in an anthropomorphic chest phantom. Methods: A Lungman phantom (Kyoto-Kagaku Co. Japan) was imaged with a GE Discovery CT750 HD CT scanner using our clinical lung nodule protocol (120kVp,80mA,0.5s,1.375:1pitch,1.25mm-slice,0.625mm-interval,40%ASIR) and lower dose protocols (20mA and 10mA), different %ASIR (0%,70%), and MBIR (VEO). A variety of 5mm-diameter simulated nodules (−630HU,100HU,water equivalent, etc.) were placed in the vasculature insert in the phantom. CT#s were measured within 7.9mm2 ROIs at the centers of the nodules and within larger ROIs in the heart and vertebra regions. Results: For nodules, on average, the CT#s are 18HU, 25HU, and 30HU greater for VEO than for 0%, 40% and 70%ASIR, respectively. The ratios of the SDs for VEO to those for 0%, 40% and 70%ASIR are 0.60, 0.77, and 0.93, respectively. For the heart region, the CT#s are independent of %ASIR at a given mA, and the CT#s for VEO are smaller than those for all ASIR blends by 10HU at 10mA, 3HU at 20mA, and 1HU at 80mA. The ratios of the SDs for VEO to those for ASIR blends increase with %ASIR and mA ranging from 0.14 for 0%ASIR/10 mA to 0.47 for 70%ASIR/80mA. Corresponding values in the spongiosa region show similar trends, with CT# differences of 35HU, 12HU, and 2HU, and SD ratios ranging from 0.13 to 0.40. Conclusions: The effect of MBIR on mean CT#s and noise depends on object size. The CT#s are greater for MBIR than ASIR blends in nodules; whereas, they are smaller for MBIR in large homogeneous regions. The noise is almost always lower for MBIR, but the degree of smoothing is much greater in large homogeneous regions than in small nodules
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
