An interventional X-ray system (10), includes a processing unit (30), a table (20) for receiving a patient (44), an X-ray image acquisition device (12) having an X-ray source (16) and an X-ray detector (18) and at least one optical camera (46) adapted for acquiring optical images of a patient (44) situated on the table (20) and for providing image data to the processing unit (30). The processing unit (30) is adapted for segmenting an outline (64) of a patient from an existing three-dimensional model, for receiving acquired images from the at least one camera (46) for determining an optical outline (66) of the patient, for registering the optical outline (66) to the outline (64) obtained in the segmentation and for determining a translation vector (48) representing a required movement of the table for coinciding a center (42) of the anatomy of interest given in the three-dimensional model with the iso-center (38) of a rotational X-ray scan that will be performed. By this process, no X-ray exposure or injection of contrast agent is required.