1. A method for reciprocally assigning a spatial position of a patient and/or a part of a patient's body and an acquired, stored patient data set, comprising the steps of: producing at least two video image recordings of the patient and/or part of the body from different recording positions via at least one video image source, wherein a three-dimensional position and/or orientation of the video image source relative to a reference coordinate system is known or can be determined; identifying corresponding tuples of points in the video image recordings; ascertaining and storing three-dimensional spatial positions from the identified tuples of points; matching the stored patient data set to a point set of the assigned spatial positions; determining a reciprocal assignment or registration of the spatial position of the patient and/or part of the body and the patient data set when the greatest or best match has been achieved.