A method for assisting optimum positioning of an occlusion site in a blood vessel in a tumor embolization is provided. Tumors are cut off from the blood supply by the embolization which is an artificial occlusion of blood vessels. The vessels around the tumor and at the same time the planned site for occlusion are firstly determined. A path from the access to the vessels can be determined based on image recognition, and with the aid of this path the site for occlusion can then be optimally determined. A computer system assists the doctor carrying out the treatment by a suitable display.
