An SVD investigation of modeling scatter in multiple energy windowsfor improved SPECT images
Kadrmas, D.J.
Frey, E.C.
Tsui, B.M.W.
Dept. of Biomed. Eng., North Carolina Univ., Chapel Hill, NC;
This paper appears in: Nuclear Science, IEEE Transactions on
Publication Date: Aug 1996
Volume: 43,
Issue: 4, Part 1
On page(s): 2275-2284
Meeting Date: 10/21/1995 - 10/28/1995
Location: San Francisco, CA, USA
ISSN: 0018-9499
References Cited: 26
CODEN: IETNAE
INSPEC Accession Number: 5371706
Digital Object Identifier: 10.1109/23.531892
Current Version Published: 2002-08-06
Abstract
In this work singular value decomposition (SVD) techniques are
used to investigate how the use of low energy photons and multiple
energy windows affects the noise properties of Tc-99m SPECT imaging. The
authors have previously shown that, when modeling scatter in the
projector and backprojector of iterative reconstruction algorithms,
simultaneous reconstruction from multiple energy window data can result
in very different noise characteristics. Further, the properties depend
upon the width and number of energy windows used. To investigate this
further, the authors have generated photon transport matrices using
models for scatter, an elliptical phantom containing cold rods of
various sizes, and a number of multiple energy window acquisition
schemes. Transfer matrices were also generated for the cases of perfect
scatter rejection and ideal scatter subtraction. The matrices were
decomposed using SVD, and signal power and projection space variance
spectra were computed using the basis formed by the left singular
vectors. Results indicate very different noise levels for the various
energy window combinations. The perfect scatter rejection case resulted
in the lowest variance spectrum, and reconstruction-based scatter
compensation performed better than the scatter subtraction case. When
including lower energy photons in reconstruction-based scatter
compensation, using a series of multiple energy windows outperformed a
single large energy window. One multiple window combination is presented
which achieves a lower variance spectrum than the standard 20% energy
window, indicating the potential for using low energy photons to improve
the noise characteristics of SPECT images
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