A computer-implemented medical method of determining the position of an anatomical region of interest of a patient's body is provided. The method includes acquiring finger model data, acquiring finger position data based on the finger model data and based on imaging the at least one finger, acquiring planning image data that describes a planning external surface of the anatomical region of interest, and determining anatomical region position data based on the finger position data and the planning image data, wherein the finger model data describes a user-specific model of the pose which is acquired by imaging the at least one finger when it attains the pose.