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Proceedings Paper

SPECT imaging: the spatial distribution of detected photons about a point source in a scatter medium
Author(s): T. van Doorn; Zixin Zhang; Milka Zec
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Paper Abstract

When photon scattering around a point source in a scatter medium is considered in isolation, the distribution of the scattering sites is radially symmetric and exponentially decreasing in frequency. Discontinuities in the scattering medium cause a disruption in this radial symmetry. However, when the limited intrinsic energy resolution of the gamma camera, the energy acceptance window and the collimator response are included in the consideration, the distribution of the scattering sites of photons accepted by the gamma camera is complex. Monte Carlo techniques (EGS4) have been used to determine the spatial distribution of the scatter sites. The results of the simulation demonstrate a prominent peak in scattering sites in front of the source with a rapid decrease in all other directions. The contribution of completely backscattered photons to a point spread function is virtually negligible. Also, a clear discontinuity in the scatter site distribution is observed at the boundary of two scatter media. The first order scatter spatial distribution has also been modelled using analytical techniques. The analytical results are in good agreement with the Monte Carlo simulation. Direct experimental verification of the results of the two simulation techniques is not possible, however, there is agreement between secondary results with experimental data, hence the analysis is valid by implication. The knowledge of the scattering site distribution is anticipated to assist in a more accurate method of image reconstruction in SPECT imaging.

Paper Details

Date Published: 1 June 1992
PDF: 12 pages
Proc. SPIE 1651, Medical Imaging VI: Instrumentation, (1 June 1992); doi: 10.1117/12.59400
Show Author Affiliations
T. van Doorn, Ctr. for Medical and Health Physics/Queensland Univ. of Technology (Australia)
Zixin Zhang, Ctr. for Medical and Health Physics/Queensland Univ. of Technology (Australia)
Milka Zec, Ctr. for Medical and Health Physics/Queensland Univ. of Technology (Australia)


Published in SPIE Proceedings Vol. 1651:
Medical Imaging VI: Instrumentation
Rodney Shaw, Editor(s)

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