QUANTITATIVE MULTI-DETECTOR EMISSION COMPUTERIZED-TOMOGRAPHY USING ITERATIVE ATTENUATION COMPENSATION

  • 1 January 1982
    • journal article
    • research article
    • Vol. 23  (8) , 706-714
Abstract
An iterative procedure to correct for attenuation was developed for a multidetector, single-photon emission tomographic scanner. The difference between measured and estimated data projections is used at each iteration to form an error image which is used, in turn, to correct the image. A damping factor that minimizes .chi.2 is applied after each iteration to speed convergence. Several phantoms of different size, with various concentration distributions, were used to compare this method with a 1st-order multiplicative attenuation correction used previously with this scanner. The 1st-order correction is inadequate for most of the phantoms studied, whereas relative and absolute quantitative capability is demonstrated for the iterative attenuation correction. The reconstructed average number of counts per pixel is a linear function of activity concentration up to .apprx. 5 .mu.Ci/ml for all regions of uniform activity whose size is .gtoreq. 5 cm. The importance of using an accurate attenuation distribution with this method is demonstrated with a torso-like phantom.

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