a two - dimensional radiation detector receives divergent ray penetrating radiation along conical or pyramidal ray paths which converge at an apex . the radiation may emanate from one or both of an x - ray tube or radionuclei injected into a human subject . as the radiation detector rotates around the subject , it is repeatedly sampled to generate two - dimensional data sets h t at each of a plurality of samplings t . each two - dimensional data array is weighted and divided into two components . a first component processor convolves a first component of each two - dimensional array with respect to u for each v . a second component processor processes a second component of each two - dimensional array including weighting each component with a geometrically dependent weighting function w from a weighting function computer . the processed first and second components are combined and backprojected .