Highlights
- •We examined the point spread function of a cross-sectional Compton image.
- •The effect of the number of views was also examined.
- •The double Lorentzian function approximated the PSF well.
- •Insufficient views caused star-shaped artifacts, but did not degrade spatial resolution.
Abstract
Introduction
We have been developing a medical imaging technique using a Compton camera, which
is expected to reconstruct three-dimensional images. If the number of views is not
sufficient, star-shaped artifacts (streak artifacts) could arise in cross-sectional
images. Therefore, we estimated the point spread function (PSF) of cross-sectional
Compton images and the effect of the number of views by Monte Carlo simulations and
experimental studies.
Materials and methods
A cross-sectional Compton image was reconstructed using a dataset comprising 719 view
directions and PSF was analyzed using a radial distribution. The peak height, full
width at half maximum (FWHM), background (BG), and residual sum of squares (RSS) were
calculated from the obtained PSF. In addition, RSSs were plotted against the number
of views to estimate the required number to suppress star-shaped artifacts.
Results
There was no correlation found between the number of views and both FWHM (16 mm) and
peak/BG ratio (∼1 × 104). RSSs were reduced with the number of views and approached the minimum asymptotically.
Correlation was observed between the required number of views and the number of Compton
events used for image reconstruction.
Conclusion
We determined the PSF of cross-sectional Compton images and the effect of the number
of views on the images. The required number of views to suppress the star-shaped artifact
is related to the square root of the number of Compton events used to reconstruct
the image. From this study, we concluded that 21 or more views are required for clinical
purposes.
Keywords
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Article info
Publication history
Accepted:
November 10,
2018
Received in revised form:
November 2,
2018
Received:
July 3,
2018
Identification
Copyright
© 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
