Localizing unit for an X-ray diagnostic system with a sterile drape

A localizing unit for an X-ray diagnostic system covered with a sterile drape is provided. In one embodiment, the localizing unit can be sterilized and has an adapter, which includes a mechanism for puncturing the sterile drape and a mechanism for temporarily securing the sterile drape on a housing of the X-ray diagnostic system. The adapter may be detachably held in predetermined holders on the housing of the X-ray diagnostic system and may be positioned on the housing in a reproducible manner. In some embodiments, the mechanism for temporarily securing the sterile drape on the housing includes an elastically deformable, surrounding seal, which upon positioning the adapter, produces a force on the sterile drape in a direction perpendicular to the surface of the housing.