The invention relates to a method for making a numerical three-dimensional model of a structure from relatively soft and relatively hard parts, comprising of making by means of penetrating radiation a plurality of numerical sections of the structure located at a mutual distance and representing the absorption for the radiation, storing in a memory the numerical sections and constructing a numerical three-dimensional model of the structure on the basis of the numerical sections stored in the memory, wherein at least during making of the sections at least a part of the relatively soft parts of the structure is provided with a layer of contrast agent with an absorption coefficient for the radiation differing substantially from that of the relatively soft parts.
