| 摘要 |
In an exemplary embodiment, a roentgenographic installation, an x-ray tube aligned with respect to the roentgenographic installation, a flange-mounted, motor adjustable primary radiation diaphragm, and a patient support which is respectively longitudinally displaceable between the x-ray tube and the roentgenographic installation. The x-ray examination apparatus possesses a program control installation, with which the patient support can be displaced in a step-by-step fashion relative to the roentgenographic installation in predetermined time intervals. During angiography of the extremities, the photographic exposure field changes in size as a consequence of the advancement of the contrast medium and the related displacement of the patient support plate relative to the photographic exposure installation. This can result in lateral halations of the examination area. In order to prevent this, the disclosure provides that a diaphragm control circuit is connected to the program control installation which allocates to every photographic exposure position, actuatable by the program control installation, a separately preselectable setpoint value for the diaphragm follow-up control.
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