Patent ID: 7573973

Claim:
A computer programmed to generate computed tomographic (CT) images from a set of projection data acquired during a CT scan, said computer programmed to: perform a cone-angle-and-image-plane-dependent view weighting, wherein the view weighting is at least partially defined by an orthogonal distance between an image plane and a central plane; apply a Feldkamp, Davis, and Kress (FDK) algorithm with the cone-angle-and-image-plane-dependent view weighting to the set of projection data; apply an FDK algorithm to a single circular source trajectory expressed as: f ⁡ ( x , y , z ) = 1 2 ⁢ ∫ 0 2 ⁢ π ⁢ [ ⅆ 2 ⁢ / ( ⅆ 2 ⁢ + Z 2 ) 1 / 2 ] ⁡ [ ∫ - ∞ + ∞ ⁢ w ⁡ ( l , α ) ⁢ S β ⁡ ( ω , Z ) ⁢ ⅇ j ⁢ ⁢ 2 ⁢ ⁢ π ⁢ ⁢ ω ⁢ ⁢ x ⁢  ω  ⁢ ⅆ ω ] ⁢ ⅆ β ; ⁢ ⁢ and S β ⁡ ( ω , Z ) = ∫ - ∞ ∞ ⁢ P β ⁡ ( t , Z ) ⁢ ⅇ - j ⁢ ⁢ 2 ⁢ π ⁢ ⁢ ω ⁢ ⁢ t ⁢ ⅆ t , where w(X) represents at least one of: w ⁡ ( l , α ) = tan g ⁡ ( l ) ⁢ α c tan g ⁡ ( l ) ⁢ α + tan g ⁡ ( l ) ⁢ α c w ⁡ ( l , α , z ) = tan ( g ⁡ ( l ) + f ⁡ ( v c ) ) ⁢ α c tan ( g ⁡ ( l ) + f ⁡ ( v ) ) ⁢ α + tan ( g ⁡ ( l ) + f ⁡ ( v c ) ) ⁢ α c , where β represents view angle; ƒ (x,y,z) represents the point to be reconstructed; P β (t,Z) represents the projection of ƒ(x,y,z) in the virtual detector D′; d represents the orthogonal distance between the x-ray focal spot and the virtual detector; Z represents the height of the projection of ƒ(x,y,z) in the virtual detector; ω represents frequency; α_≡α(x,y,z) that represents the cone angle of the ray emanating from the focal spot and passing through a point P, wherein α(x,y,z) is dependent on a coordinate (x,y,z) of the point P; l≡l(z) that represents an orthogonal distance between an imaging plane (IP) and a central plane (CP), wherein l(z) is dependent on a z-coordinate of the point P g(l) is a positive monotonically increasing function over distance l; α c represents a cone angle of a conjugate ray to the ray emanating from the focal spot and passing through a point P; and ν and ν c are the vertical coordinates of the projection of pixel P in the detector corresponding to each conjugate ray, respectively.