1. A method to operate an angiographic examination system to conduct a rotational angiography of an examination subject around an isocenter of the angiographic examination system, said method comprising: (S 1 ) placing an examination subject on a patient support and acquiring two x-ray projections of the examination subject, respectively from different acquisition angles, by rotating at least one C-arm-mounted x-ray radiator and x-ray image detector around the patient on the patient support; (S 2 ) providing said two x-ray projections to a computer and, in said computer, automatically segmenting the x-ray projections to generate outer contours of the patient in each of said two x-ray projections; (S 3 ) in said computer, automatically discretizing said outer contours in each of said two x-ray projections; (S 4 ) in said computer, automatically calculating coordinates of focal points of the patient from discrete points in each of said two x-ray projections produced by said discretization of said outer contours; (S 5 ) in said computer, automatically determining deviations of said coordinates of the respective focal points of the patient; (S 6 ) in said computer, automatically evaluating said deviations of said coordinates to produce an evaluation result; and (S 7 ) presenting said evaluation result in a humanly perceptible form as an output from said computer in communication with said computer.