A positioning unit includes a projector and a control unit and enables a particularly quick and precise positioning of a patient. In an embodiment, the control unit affects a control of the projector as a function of a protocol for a recording of an image of the patient such that the positioning unit is designed for the planar projection of a figure as a positioning aid on the patient couch. An immediately apparent area on the patient couch is then specified by the figure projected in a planar fashion, relative to which the patient can be positioned. The control unit can be used both to temporally control the projection process and also to control the figurative properties of the positioning aid. Furthermore, the control unit can include a device for calculating a control signal so that the control unit brings about control of the projector with the control signal.
