(Tuesday, 7/31/2018) 1:45 PM - 3:45 PM
Room: Room 207
Purpose: To compare radiation dose and image quality of conventional CT images produced by both a Spectral MECT scanner and a conventional MDCT scanner for routine pediatric brain and abdomen protocols.
Methods: To assess dose, a 3-piece CTDI phantom was scanned on a 128-detector Spectral MECT and 256-detector MDCT (IQon Spectral and Brilliance iCT, Philips, Cleveland, OH). Abdomen protocols were scanned using automatic exposure control and image quality reference parameters were matched on both scanners. Four weight-based abdominal MDCT protocols were used with 80, 100, and 120 kVp. A single abdominal MECT protocol was used at 120 kVp. On both scanners, four age-based head protocols at 120 kVp with fixed effective mAs were used to scan 10 and 16 cm CTDI phantom components. Ion chamber (Radcal Corporation, Monrovia, CA) and nanoDot dosimeter (Landauer, Glenwood, IL) measurements were recorded both centrally and at peripheral locations of the phantoms.
The 10 cm CTDI insert was replaced with a 10 cm low contrast phantom (QRM, Möhrendorf, DE) and scans repeated with effective mAs matched to the previous scans. Images were reconstructed with iterative reconstruction (iDose4 3mm slice thickness or IMR 1mm slice thickness) using a soft tissue/standard reconstruction kernel. Contrast-to-noise (CNR) ratios were calculated from a circular ROI drawn centrally and in a low contrast object.
Results: Depending on phantom size, measurement location, and protocol choice, nanoDot and ion chamber measurements showed differences of up to 22.9% more dose or 18.9% less dose for Spectral MECT compared to MDCT. CNR calculations showed equal or improved image quality using Spectral MECT compared to MDCT for most combinations of reconstruction, protocol, and phantom size. CNR was on average 10.72% greater for head protocols for Spectral MECT compared to MDCT.
Conclusion: Comparable dose and image quality was observed on conventional images generated with either MDCT or MECT.
Authors:
Dianna M. E. Bardo, MD, Richard N. Southard, MD, Robyn Augustyn, RT (CT), Marrit Thorkelson, RT (MR), Nicholas Rubert, PhD
Keywords
Not Applicable / None Entered.
Taxonomy
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