Method for temporarily marking a region of interest (ROI) on a patient (5), comprising- providing a medical imaging device (1) having a bore (7) and a table (4), wherein the table (4) is transferable between a first position, in which at least a part of the patient (5) is located inside the bore (7), and a second positon, in which at least the part of the patient (5) is located outside the bore (7), wherein a medical image data set (11) of the patient (5) is recorded by the medical imaging device (1) in the first position；- providing an optical sensor for recording an image of the patient (5) for registering a position and/or a motion of the patient；- providing a light source for marking a spot on a body surface of the patient (5) as region of interest (ROI) in the second position,wherein for matching the coordinate systems of the medical imaging device and the optical sensor, the medical imaging device and the optical sensor are calibrated with each other.
