Computer tomographic method and a computer tomograph

A computer tomography method for obtaining amapping of a variable in an object, said variable being measured in the form of line integral values over a multitude of lines, crossing said object, the multitude of measured lines being subdivided into families of lines, which families are enumerable in an order determined by successive relative angular shifts between patterns of lines in successive families, characterized in that

• a) in a first step, groups are combined out of said families, each group consisting of a first prime number of families of lines having adjacent position in said order, said lines of said highest and lowest order of families forming a multitude of intersection points between lines belonging to one famly and lines belonging to another family, and calculating for each of said intersection points of the sum of the line integral values for the two respective said lines intersecting at that point, and further adding values interpolated to said points from eventual intermediate families, said first step resulting, for each said group of families, in a plurality of points in a plane, for which points individual sum values are stored, said sums forming space distributions, one for each said group,
• b) in a successive step combining a further prime number of previously combined groups, with their calculated space distributions, representative of adjacent positions in said order into further groups representative of a number of families which is said further prime number times that of an immediately preceding step, having successive positions in said order, and calculating for points of intersection between those lines belonging to the families of the lowest and highest order within the number of families comprised in each combined group, of sums of values representative of the two respective space distributions, and summing thereto values for the aforesaid points of intersection taken for distributions belonging to eventual intermediate groups, either for points coinciding with those having calculated individual sums using such sums, or, for points not so coinciding, adding values interpolated from adjacent points in a respective space distribution, forming in said successive step higher order space distributions, to a number which is reduced by the factor of said further number compared to that of the starting point of said successive step,
• c) and repeating said second step until obtension of a final space distribution.