The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 24, 1996
Filed:
Dec. 28, 1994
Gengsheng L Zeng, Salt Lake City, UT (US);
Grant T Gullberg, Salt Lake City, UT (US);
The University of Utah, Salt Lake City, UT (US);
Abstract
A subject (12) in an examination region is injected with a radioisotope that emits radiation. A detector head (18) receives emission radiation projections (28a) from the radioisotope and transmission radiation projections (28b) from a transmission radiation source (22) disposed opposite the subject from the detector head. A volume memory (50) stores an estimated volume image. For each actually collected image emission data projection set, a projector (52) reprojects a set of projection of the volume image from the image memory (50) along each of the same projection directions as the emission data projections. Each projection is rotated (80) and warped (82) such that rays which converge with the same angle as the convergence of the collimator on the detector head become parallel. The layers are each convolved with a point response function (84) weighted in accordance with a depth of the corresponding layer in the volume image and corresponding points are summed (92) to create a reprojected projection. A ratio of each collected projection and the reprojected projection is calculated (54) and backprojected (56) into a volume of correction factors (58). The backprojectioned correction factors for the set of ratios are summed. A memory updating algorithm (76) multiplies the estimated volume image in the image memory (50) by the sum of the correction factors (58). This process is repeated iteratively over a plurality of projection directions, each iteration further refining the volume image in the volume image memory (50).