Abstract
Objective
The objective was to compare standard-dose chest computed tomography (CT) reconstructed
with filtered back projection (FBP) versus low-dose images with FBP and raw-data-based
iterative reconstruction.
Methods
Eighty-seven consecutive patients (46 male; mean age, 54.54±16.12; mean body mass
index, 24.58±4.07) referred for initial chest CT with full-dose examinations [mean
dose–length product (DLP), 183.37±44.13 mGy·cm] and follow-up chest CT with half-dose
examinations (mean DLP, 91.08±23.81 mGy·cm) were included. The full-dose protocol
was reconstructed with FBP; the half-dose protocol was reconstructed with FBP and
sinogram-affirmed iterative reconstruction (SAFIRE). Noise and signal-to-noise ratio
were compared using a paired Student’s t test; subjective image quality and lesion conspicuity were compared using Wilcoxon
signed ranks test.
Results
Actual radiation dose of follow-up CT was about 50% (49.26%±2.62%) of standard-dose
protocol. Compared to full-dose images with FBP, there was no significant difference
in half-dose images with SAFIRE in the objective noise (ascending aorta: P=.38, descending aorta: P=.70, trachea on mediastinal images: P=.37) and SNR (ascending aorta: P=.14, descending aorta: P=.72, trachea on mediastinal images: P=.06) on mediastinal images. Noise was significantly lower (P<.001) and SNR was significantly higher (P<.001) in half-dose images with SAFIRE on lung images. Noise was significantly higher
(P<.001) and SNR was significantly lower (P<.001) in half-dose images with FBP. Subjective image quality was similar on both mediastinal
images (P=.317) and lung images (P=.614) of half-dose SAFIRE images versus full-dose FBP images. Lesion conspicuity was
also similar. Subjective image quality was significantly lower on both mediastinal
images (P<.001) and lung images (P<.001) of half-dose FBP images versus full-dose FBP images. The conspicuity of some
lesions was significantly lower (ground-glass opacity, P<.0001; ill-defined micronodule, P<.0001; lung cyst, P<.0001; emphysematous lesion, P=.003) on half-dose FBP versus full-dose FBP images.
Conclusion
Compared to full-dose CT images reconstructed with the conventional FBP algorithm,
SAFIRE with three iterations could provide similar or better image quality at 50%
less dose.
Keywords
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Article info
Publication history
Published online: August 05, 2013
Accepted:
June 5,
2013
Received in revised form:
March 27,
2013
Received:
July 24,
2012
Identification
Copyright
© 2013 Elsevier Inc. Published by Elsevier Inc. All rights reserved.
