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:
Mar. 14, 1989
Filed:
Jul. 31, 1986
Grant T Gullberg, Salt Lake City, UT (US);
Carl R Crawford, Milwaukee, WI (US);
General Electric Company, Waukesha, WI (US);
Abstract
Method and means for determining and compensating for a shift in the center of rotation of a fan beam CT reconstruction apparatus. Known reconstruction algorithms for fan beam computed tomography are based on the assumption that the center of rotation of the source or detector is on the midline of the fan. In certain cases due, for example, to machine inaccuracies, the center of rotation can be shifted from the assumed center, and such shift can cause artifacts in the reconstruction. The present invention provides a procedure for estimating the magnitude of the shift and also accommodates for the shift by applying a series of weighting factors to the projection information which are dependent on the magnitude of the shift. The weighted projections are then processed by the usual convolution operation, and the convolved projection sets back projected using a geometry modified to account for the shift. Efficiencies are achieved in that all projection sets can be weighted and convolved before back projection, and existing back projection hardware or software can be used to map the modified projection sets into the pixelized image space.