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Optical Engineering

Radial noise filtering in positron emission tomography
Author(s): Mongi A. Abidi; Paul B. Davis
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Paper Abstract

The quality of the images from positron emission tomography (PET) is regularly degraded by radial streak artifacts. In many cases this is attributed to data undersampling and the inexactitude of the models used in the image reconstruction. Because this noise cannot be easily isolated in either spatial or spectral domains, classical noise filtering techniques have proven inadequate. As an alternative, we propose a new filtering method, which is implemented as follows. The image is converted from the original rectangular x-y coordinate system into a polar ρ-θ coordinate system. This causes the radial noise to map into well-defined horizontal streaks. After a polar transformation, radial noise is mapped around one of the axes of the Fourier spectrum in the corresponding ω-m space. We have modeled radial noise using both rectangular and polar representations and have shown both analytically and through computer simulation that these streaks exhibit consistent mapping patterns. A class of filters is designed accordingly and applied to the image. The filtered image is then converted back to the rectangular coordinate system. This method has been tested using both synthetic and real data. It has shown little or no sensitivity to variations in the image data. Visual inspection of the filtered images show clear enhancement over the original images. Extreme levels of radial noise were removed with no apparent loss of sharpness around dominant features in the image.

Paper Details

Date Published: 1 May 1990
PDF: 8 pages
Opt. Eng. 29(5) doi: 10.1117/12.55625
Published in: Optical Engineering Volume 29, Issue 5
Show Author Affiliations
Mongi A. Abidi, Univ. of Tennessee/Knoxville (United States)
Paul B. Davis

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