A medical data processing method of determining anatomical structure subset data describing a subset of a graphical representation 9 of an anatomical structure of a patient's body to be displayed simultaneously with a medical image of an anatomical body part 1, the method being constituted to be executed by a computer and comprising the following steps: a) acquiring predetermined anatomical structure representation data describing a graphical representation of the anatomical structure and its position in the patient's body； b) acquiring anatomical body part image data describing an image of an anatomical body part 1 of the patient imaged by an optical imaging apparatus 2 for display by a display apparatus 3； c) acquiring optical parameter data describing an optical parameter WD serving as a basis for displaying the anatomical body part image data； d) determining, based on the anatomical structure representation data and the anatomical body part image data and the optical parameter data, anatomical structure subset data describing a subset 9 of the anatomical structure representation data, which subset describes graphical representation of a structure subset of the anatomical structure to be displayed simultaneously with the image of the anatomical body part 1.
