A transmission-dependent method for scatter correction in SPECT

S. R. Meikle*, B. F. Hutton, D. L. Bailey

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    145 Citations (Scopus)

    Abstract

    A method of scatter compensation has been developed that incorporates planar transmission measurements in the estimation of photopeak scatter in SPECT. Methods: The scatter distribution is first estimated by convolving the planar projections with a monoexponential scatter function. The number of scattered events that subsequently reach the detector as a proportion of total events (i.e., scatter fraction) is then determined for each point in the projections based on narrow-beam transmission values, obtained using an external source. The assumptions of the method were tested using 99mTc and 201Tl point and line sources. The quantitative and qualitative impact of transmission-dependent scatter correction was assessed in realistic phantom experiments simulating blood-pool, lung and myocardial perfusion studies. Results: The method accurately predicts the scatter distribution from 99mTc and 201Tl line sources in a phantom with variable density. Reconstructed counts are artificially enhanced in regions of high tissue density when scattered events are not removed from the projections prior to attenuation correction. Using convolution-subtraction with a constant scatter fraction (k = 0.4), scatter is underestimated in the heart and overestimated in the lungs, whereas transmission-dependent scatter correction enables activity to be quantified with ≥95% accuracy in heart and lung regions. Conclusion: We conclude that incorporating transmission data enables accurate scatter compensation in objects with nonuniform density.

    Original languageEnglish
    Pages (from-to)360-367
    Number of pages8
    JournalJournal of Nuclear Medicine
    Volume35
    Issue number2
    Publication statusPublished - 1994

    Keywords

    • attenuation correction
    • Compton scattering
    • quantitative SPECT
    • transmission tomography

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