Angiography system for the angiographic examination of a patient and angiographic examination method

An angiography system for an angiographic examination on an examination object of a patient, comprising:

• an x-ray emitter attached to an end of a C-arm;
• an x-ray detector attached to another end of the C-arm;
• a patient support couch for supporting the patient;
• a system control unit;
• and
• a monitor,
• wherein the system control unit is configured to:
• detect a reference image that is adapted to a different or a changed imaging geometry of the angiography system,
• register the reference image to the C-arm,
• segment the examination object in the reference image if necessary,
• generate a mask image from the reference image with image regions lying within the segmentation being contrasted, and
• subtract the mask image from fluoroscopy live images acquired by the angiography system without administrating contrast agent, and
• generate a roadmap image from the subtraction, and
• wherein the roadmap image is displayed on the monitor.