A method is provided for determining a position of an object within a breast of a female patient in a simple manner from a three-dimensional image taken of the breast. A simplified model is made of an internal structure of a breast having glandular bodies leading via lactiferous ducts to an outlet at a nipple. A particularly advantageous model is a tree-type structure in which branches correspond to lactiferous ducts and leaves correspond to glandular bodies. Furthermore, a determination is made of whether the object has contact with an element of the tree-type structure. Alternatively, a distance to an element of the tree-type structure is established. By correlating tree-type structures derived from various images taken on the same breast, the location of the object can be unequivocally established.