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Proceedings Paper

Convolution estimation of spill-down and scatter in dual isotope (99mTc/111In) SPECT
Author(s): Jian Feng; Bill C. Penney; Xiaochuan Pan
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Paper Abstract

Accurate attenuation correction in dual isotope single photon emission computed tomography (SPECT) requires spill-down and scatter correction. Convolution methods that allow such correction were investigated. Three energy windows were used: 1) a Compton scatter window placed below the Tc-99m photopeak window, 2) the Tc-99m photopeak, and 3) both In-111 photopeaks. Spill-down of In-111 into the Tc-99m window was measured using a small source of In-111 at depths of 5, 7, 9, and 11cm. From these data, the convolution kernel relating the In-111 image and the Tc-99m window spill-down image was computed for each depth. Using a small Tc-99m source at the same depths, the convolution kernels describing its spill-down into the Compton window were computed. A factor to scale the Tc-99m spill-down estimate by for obtaining the self-scatter estimate was determined from the total counts in the Tc-99m photopeak vs. the Compton scatter window when primary photons were blocked with a small lead disk. Depths of 5 and 9cm were optimal for spill-down and Tc-99m self-scatter correction, respectively. It was demonstrated that the spill-down and scatter correction increased effective attenuation coefficient towards its 'no-scatter' value and dramatically decreased the intensity of an In-111 source in Tc-99m projection images.

Paper Details

Date Published: 3 May 2002
PDF: 9 pages
Proc. SPIE 4682, Medical Imaging 2002: Physics of Medical Imaging, (3 May 2002); doi: 10.1117/12.465618
Show Author Affiliations
Jian Feng, Univ. of Chicago (United States)
Bill C. Penney, Univ. of Chicago (United States)
Xiaochuan Pan, Univ. of Chicago (United States)

Published in SPIE Proceedings Vol. 4682:
Medical Imaging 2002: Physics of Medical Imaging
Larry E. Antonuk; Martin Joel Yaffe, Editor(s)

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