1. A method for performing iterative reconstruction of three dimensional image data in (x, y, z) coordinate space comprising the steps of: a) arranging said three dimensional image data in a linogram representation such that said data lie on a plurality of x,y planes tilted from the (x, y, 0) plane by z′(ψ)=z+tan τ×(y cos ψ−x sin ψ), where τ is a tilt angle and ψ is an orientation angle; b) forming forward projections in said linogram representation using an Approximate Discrete Radon Transform (ADRT) method; and c) forming back projections in said linogram representation using said ADRT method.