Panel Disdussion

3rd International Congress 3rd International of Nuclear Congress Medicine of Nuclear & 15th Medicine Iranian Annual & 15th Iranian Congress Annual of
Nuclear Congress Medicine of Nuclear Medicine
Shahid Beheshti Shahid Beheshti University University of Medical Sciences of Medical 19-21 Sciences May 201119-21 May 2011
Weighting Coefficient Studies for Compton Scattering Effect
Compensation in SPECT Imaging Using Monte-Carlo
Simulation
Firouz Payervand, Mansour Ashoor, Ali Ramezani Moghaddam
Nuclear Science & Technology Research Institute
The aim of single photon emission computed tomography is to
provide accurate images of the radionuclide distribution after
injecting and to provide metabolic and physiologic functional data of
some internal organs of the object being scanned. The inclusion of
scatter radiation in the projections is one of the main sources of error
in SPECT imaging.Tthe detection of scattered events affects the
contrast, the signal to noise ratio and the resolution of the images. At
the photon energies of interest in SPECT imaging, Compton scattering
is the dominant mode of interaction. During Compton scattering, the
photon is reduced in energy as well as deflected from its original
path. Thus one can use energy loss and energy windowing to reduce
the amount of scattered photons imaged. Several methods for the
effects of scattered events have been proposed. The difference
between methods is the way of estimating the scatter contribution.
To modeling imaging systems or developing algorithms or evaluating
and improving those methods, one can use Monte-Carlo simulation
code. In this paper to evaluating and improving Energy Window
Subtraction (EWS), MCNP code has been used and then scatter
phenomena has been studied and the best weighting coefficient and
the appropriate position and width of each energy window has been
determined and quantitative parameters of image have been studied.
Generally, with using the result of this paper and the mathematical
modeling, one can eliminates scattering effects. Simulation results
showed that by operating weighting coefficients we can improve
quantitative parameters of image and provide suitable images with
anatomical and physiological data of internal organs.
Keywords: Compton scattering, Photo eak, SPECT, MCNP Code
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