Experimental determination of the weighting factor for the energy window subtraction-based downscatter correction for I-123 in brain SPECT studies
Correction for downscatter in I-123 SPECT can be performed by the subtraction of a secondary energy window from the main window, as in the triple-energy window method. This is potentially noise sensitive. For studies with limited amount of counts (e.g. dynamic studies), a broad subtraction window wi...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Wolters Kluwer Medknow Publications
2010-01-01
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| Series: | Journal of Medical Physics |
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| Online Access: | http://www.jmp.org.in/article.asp?issn=0971-6203;year=2010;volume=35;issue=4;spage=215;epage=222;aulast=de |
| _version_ | 1819264119635705856 |
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| author | de Nijs Robin Holm Søren Thomsen Gerda Ziebell Morten Svarer Claus |
| author_facet | de Nijs Robin Holm Søren Thomsen Gerda Ziebell Morten Svarer Claus |
| author_sort | de Nijs Robin |
| collection | DOAJ |
| description | Correction for downscatter in I-123 SPECT can be performed by the subtraction of a secondary energy window from the main window, as in the triple-energy window method. This is potentially noise sensitive. For studies with limited amount of counts (e.g. dynamic studies), a broad subtraction window with identical width is preferred. This secondary window needs to be weighted with a factor higher than one, due to a broad backscatter peak from high-energy photons appearing at 172 keV. Spatial dependency and the numerical value of this weighting factor and the image contrast improvement of this correction were investigated in this study. Energy windows with a width of 32 keV were centered at 159 keV and 200 keV. The weighting factor was measured both with an I-123 point source and in a dopamine transporter brain SPECT study in 10 human subjects (5 healthy subjects and 5 patients) by minimizing the background outside the head. Weighting factors ranged from 1.11 to 1.13 for the point source and from 1.16 to 1.18 for human subjects. Point source measurements revealed no position dependence. After correction, the measured specific binding ratio (image contrast) increased significantly for healthy subjects, typically by more than 20%, while the background counts outside of all subjects were effectively removed. A weighting factor of 1.1-1.2 can be applied in clinical practice. This correction effectively removes downscatter and significantly improves image contrast inside the brain. |
| first_indexed | 2024-12-23T20:24:25Z |
| format | Article |
| id | doaj.art-6d3fab4313eb4974b6255d8c00bf2d14 |
| institution | Directory Open Access Journal |
| issn | 0971-6203 1998-3913 |
| language | English |
| last_indexed | 2024-12-23T20:24:25Z |
| publishDate | 2010-01-01 |
| publisher | Wolters Kluwer Medknow Publications |
| record_format | Article |
| series | Journal of Medical Physics |
| spelling | doaj.art-6d3fab4313eb4974b6255d8c00bf2d142022-12-21T17:32:25ZengWolters Kluwer Medknow PublicationsJournal of Medical Physics0971-62031998-39132010-01-01354215222Experimental determination of the weighting factor for the energy window subtraction-based downscatter correction for I-123 in brain SPECT studiesde Nijs RobinHolm SørenThomsen GerdaZiebell MortenSvarer ClausCorrection for downscatter in I-123 SPECT can be performed by the subtraction of a secondary energy window from the main window, as in the triple-energy window method. This is potentially noise sensitive. For studies with limited amount of counts (e.g. dynamic studies), a broad subtraction window with identical width is preferred. This secondary window needs to be weighted with a factor higher than one, due to a broad backscatter peak from high-energy photons appearing at 172 keV. Spatial dependency and the numerical value of this weighting factor and the image contrast improvement of this correction were investigated in this study. Energy windows with a width of 32 keV were centered at 159 keV and 200 keV. The weighting factor was measured both with an I-123 point source and in a dopamine transporter brain SPECT study in 10 human subjects (5 healthy subjects and 5 patients) by minimizing the background outside the head. Weighting factors ranged from 1.11 to 1.13 for the point source and from 1.16 to 1.18 for human subjects. Point source measurements revealed no position dependence. After correction, the measured specific binding ratio (image contrast) increased significantly for healthy subjects, typically by more than 20%, while the background counts outside of all subjects were effectively removed. A weighting factor of 1.1-1.2 can be applied in clinical practice. This correction effectively removes downscatter and significantly improves image contrast inside the brain.http://www.jmp.org.in/article.asp?issn=0971-6203;year=2010;volume=35;issue=4;spage=215;epage=222;aulast=deweighting factorsdownscatter correctionSPECTiodine-123energy window subtraction |
| spellingShingle | de Nijs Robin Holm Søren Thomsen Gerda Ziebell Morten Svarer Claus Experimental determination of the weighting factor for the energy window subtraction-based downscatter correction for I-123 in brain SPECT studies Journal of Medical Physics weighting factors downscatter correction SPECT iodine-123 energy window subtraction |
| title | Experimental determination of the weighting factor for the energy window subtraction-based downscatter correction for I-123 in brain SPECT studies |
| title_full | Experimental determination of the weighting factor for the energy window subtraction-based downscatter correction for I-123 in brain SPECT studies |
| title_fullStr | Experimental determination of the weighting factor for the energy window subtraction-based downscatter correction for I-123 in brain SPECT studies |
| title_full_unstemmed | Experimental determination of the weighting factor for the energy window subtraction-based downscatter correction for I-123 in brain SPECT studies |
| title_short | Experimental determination of the weighting factor for the energy window subtraction-based downscatter correction for I-123 in brain SPECT studies |
| title_sort | experimental determination of the weighting factor for the energy window subtraction based downscatter correction for i 123 in brain spect studies |
| topic | weighting factors downscatter correction SPECT iodine-123 energy window subtraction |
| url | http://www.jmp.org.in/article.asp?issn=0971-6203;year=2010;volume=35;issue=4;spage=215;epage=222;aulast=de |
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