A1 Refereed original research article in a scientific journal
Evaluation of penetration and scattering components in conventional pinhole SPECT: phantom studies using Monte Carlo simulation
Authors: Deloar HM, Watabe H, Aoi T, Iida H
Publisher: IOP PUBLISHING LTD
Publication year: 2003
Journal: Physics in Medicine and Biology
Journal name in source: PHYSICS IN MEDICINE AND BIOLOGY
Journal acronym: PHYS MED BIOL
Article number: PII S0031-9155(03)57560-1
Volume: 48
Issue: 8
First page : 995
Last page: 1008
Number of pages: 14
ISSN: 0031-9155
DOI: https://doi.org/10.1088/0031-9155/48/8/303
Abstract
In quantitative pinhole SPECT, photon penetration through the collimator edges (penetration), and photon scattering by the object (object scatter) and collimator (collimator scatter) have not been investigated rigorously. Monte Carlo simulation was used to evaluate these three physical processes for different tungsten knife-edge pinhole collimators using uniform, hotspot and donut phantoms filled with Tl-201, Tc-99m, I-123 and I-131 solutions. For the hotspot phantom, the penetration levels with respect to total counts for a I mm pinhole aperture were 78%, 28% and 23% for I-131, I-123 and Tc-99m, respectively. For a 2 mm aperture, these values were 65% for I-131, 16% for I-123 and 12% for Tc-99m. For all pinholes, Tl-201 penetration was less than 4%. The evaluated scatter (from object and collimator) with a hotspot phantom for the I mm pinhole was 24%, 16%, 18% and 13% for Tl-201, Tc-99m, I-123 and I-131, respectively. Summation of the object and collimator scatter for the uniform phantom was approximately 20% higher than that for the hotspot phantom. Significant counts due to penetration and object and collimator scatter in the reconstructed image were observed inside the core of the donut phantom. The collimator scatter can be neglected for all isotopes used in this study except for I-131. Object scatter correction for all radionuclides used in this study is necessary and correction for the penetration contribution is necessary for all radionuclides but Tl-201.
In quantitative pinhole SPECT, photon penetration through the collimator edges (penetration), and photon scattering by the object (object scatter) and collimator (collimator scatter) have not been investigated rigorously. Monte Carlo simulation was used to evaluate these three physical processes for different tungsten knife-edge pinhole collimators using uniform, hotspot and donut phantoms filled with Tl-201, Tc-99m, I-123 and I-131 solutions. For the hotspot phantom, the penetration levels with respect to total counts for a I mm pinhole aperture were 78%, 28% and 23% for I-131, I-123 and Tc-99m, respectively. For a 2 mm aperture, these values were 65% for I-131, 16% for I-123 and 12% for Tc-99m. For all pinholes, Tl-201 penetration was less than 4%. The evaluated scatter (from object and collimator) with a hotspot phantom for the I mm pinhole was 24%, 16%, 18% and 13% for Tl-201, Tc-99m, I-123 and I-131, respectively. Summation of the object and collimator scatter for the uniform phantom was approximately 20% higher than that for the hotspot phantom. Significant counts due to penetration and object and collimator scatter in the reconstructed image were observed inside the core of the donut phantom. The collimator scatter can be neglected for all isotopes used in this study except for I-131. Object scatter correction for all radionuclides used in this study is necessary and correction for the penetration contribution is necessary for all radionuclides but Tl-201.
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