Testing of local gamma-ray scatter fractions determined by spectral fitting.

Published

Journal Article

The spectral-fitting method of correction for gamma-ray Compton scattering within objects separates the unscattered and scattered components of locally measured energy spectra. Here, we employ a third-order polynomial for the scattering and an approximately constant fitting window. A scatter fraction, defined as total scattered over total unscattered counts within a 20% window, is calculated for each point in our Anger camera images. These scatter fractions are tested against those from Monte-Carlo simulation for 99mTc and against results from semiconductor detector measurements for 131I. A radioactive sphere at several locations within a non-radioactive cylinder and the inverse are imaged for the testing. For one case, reproducibility of the spectral-fitting scatter fraction as a function of the number of unscattered counts within the 20% acceptance window was also determined. With 99mTc, for all cases, the agreement between spectral fitting and the standard estimation method is within 16%. With 131I, for the 'hot' sphere at two locations, the agreement is within 21%. For the 'hot' sphere at the third location (off the cylinder axis towards the camera), the dependence of scatter fraction on transverse distance is good although the absolute values are too large. Scatter fraction reproducibility is within 10% for 1000 or more counts. Therefore, further testing of spectral fitting and initial application to realistic clinical images seem to be in order.

Full Text

Duke Authors

Cited Authors

  • Koral, KF; Wang, X; Zasadny, KR; Clinthorne, NH; Rogers, WL; Floyd, CE; Jaszczak, RJ

Published Date

  • February 1991

Published In

Volume / Issue

  • 36 / 2

Start / End Page

  • 177 - 190

PubMed ID

  • 2008445

Pubmed Central ID

  • 2008445

International Standard Serial Number (ISSN)

  • 0031-9155

Language

  • eng

Conference Location

  • England