of the transform along the path of the ray is retained each of these transforms is added into a two or thee dimensional array if the three dimensional distribution is being imaged the transform is a plane of numbers which is added into the three dimensional array at right angles to the path of the ray the numbers in the array are corrected for the non uniform density of data after enough such rays in enough different directions are applied the distribution of the property is obtained by taking the inverse fourier transform of the data in the array application_number US 70900204 A description the rbr method can be applied equally well to a wide range of imaging technologies and in particular to any of the several ways in which cone beams are used in ct including helical scanning and tomosynthesis the following embodiment shows how to apply the invention to one specific geometry that incorporates x rays and cone beam geometry the following geometry has a fixed cylinder of detector elements and a single rotating source that provides a cone beam of x rays the geometry will be described with reference to the drawings fig1 a shows a very simple cone beam consisting of nine rays arranged in three rows 1 2 3 parallel to the x axis and three columns a b c parallel to the z axis the three rays in row 2 are on the x axis and the three rays in column b are on the z axis the source 4 and the ray at the intersection of row 2 and column b or ray 2 b are both on the z axis fig1 b shows the nine corresponding f component planes in f.