Cone-beam correction for 3rd generation multislice CT

Describes a rigorous adaptation of the circular source trajectory cone-beam algorithm (“FDK”) to the third-generation, helical multislice CT geometry. The authors then describe two practical implementations, one designed to get high image quality (HQ) and the other for high speed patient coverage (HS). Exact conversion of FDK to 3 generation geometry requires 1) interpolation of projection data onto planar projections and 2) new kernel and pre- and post-convolution weights for the filter. For small cone-angles, an approximation leads to an implementation similar to the current (flat-panel) FDK algorithm and data flow. Comparison of preliminary results with helical weighting approaches which ignore the cone angle altogether demonstrate significant image quality improvement, even for the small cone-angles associated with current multislice systems