TITLE:
Phantom study of the impact of adaptive statistical iterative reconstruction (ASiRTM) on image quality for paediatric computed tomography
AUTHORS:
Angjelina Protik, Karen Thomas, Paul Babyn, Nancy L. Ford
KEYWORDS:
Image Analysis; CT; Optimization; ASiRTM; Paediatric Imaging
JOURNAL NAME:
Journal of Biomedical Science and Engineering,
Vol.5 No.12A,
December
31,
2012
ABSTRACT:
Quantitative
analysis of image quality will be helpful for designing ASiRTM-enhanced
paediatric CT protocols, balancing image quality and radiation dose. Catphan600
phantom studies were performed on a GE Discovery HD750 64-slice CT scanner.
Images were reconstructed with 0% - 100% ASiRTM (tube current 150 mA,
variable kVp 80 - 140) in order to determine the optimal ASiRTM-Filtered
Back Projection (FBP) blend. Images reconstructed with a 50% ASiRTM-50% FBP blend were
compared to FBP images (0% ASiRTM) over a wide range of
kVp (80 - 140) and mA (10 - 400) values. Measurements of image noise, CT number
accuracy and uniformity, spatial and contrast resolution, and low contrast
detectability were performed on axial and reformatted coronal images.
Improvements in CNR, low contrast detectability and radial uniformity were
observed in ASiRTM images compared to FBP images. 50% ASiRTM was associated with a
26% - 30% reduction in image noise. Changes in noise texture were observed at
higher % ASiRTM blends with impact on visualisation of low and high
contrast objects. A small decrease in limiting spatial resolution was detected
with addition of ASiRTM, more appreciable at very low tube currents.
The preferred blend for paediatric body protocols in our study, as determined
by the image quality parameters investigated, was 50% ASiRTM when used with tube
currents greater than 50 mA.