METHOD FOR DISTINGUISHING BETWEEN FOUR MATERIALS IN TOMOGRAPHIC RECORDS OF A DUAL-ENERGY CT SYSTEM

A method and a CT system are disclosed having a computation unit for distinguishing between four materials (M1, M2, M3, M4) in tomographic records of a dual-energy CT system, wherein the size of a two-dimensional or three-dimensional viewing area is defined around each voxel whose material content is to be distinguished. In an embodiment of the method, the adjacent voxels from the viewing area on an HU value diagram are imaged for each voxel (Vi) whose material content is to be distinguished, the distances from the diagonals are calculated for all the imaged voxels, and the mean squares of these distances are formed (x12, x22). If the mean square distance (x12, x22) to one diagonal is less than to the other diagonal, then the composition of the voxel is assumed to be composed of the materials to whose diagonal the lower mean square distance (x12, x22) occurs.