Patent ID: 7062009

Claim:
A CT system for reconstructing at least one image of an object, said system comprising: a. an x-ray source for generating x-rays, said x-ray source being mounted on a gantry for rotation about an axis; b. an x-ray detector system mounted opposite said x-ray source for providing a set of projection data with respect to said object as the object is translated along said axis, said x-ray detector system including a plurality of rows of detector elements; wherein for each detector element, a corresponding detector ray is defined by x-ray photons traveling from said x-ray source to said detector element; and wherein said detector rays define an x-ray beam that is asymmetric in a plane perpendicular to said axis, said x-ray beam including a symmetric region in which one or more complementary rays can be found for each detector ray, and an asymmetric region in which no complementary ray can be found for any detector ray; c. an interpolator for interpolating said projection data from each detector element onto a slice plane by multiplying said data with helical interpolation weights; wherein for projection data resulting from detector rays lying within the symmetric region of said x-ray beam, the helical interpolation weights are complementary interpolation weights that weigh the data from complementary rays in proportion to the distance from each detector element row to said slice plane; and wherein for projection data resulting from detector rays that lie within the asymmetric region of said x-ray beam, the helical interpolation weights are direct interpolation weights that weigh the data at a given azimuthal angle from different rows in proportion to the distance from each detector element row to said slice plane; and d. an image reconstructor for reconstructing a tomographic image of said object using said helically interpolated projection data.