In order to provide a dental X-ray diagnostic installation for producing panoramic tomograms of the jaw of the patient and to achieve a simple structure with improved image quality, the apparatus includes an adjustment mechanism for the carrier of the radiation source and the film cassette holder to be adjusted in an orbital curve corresponding to the dental arch of the patient. The adjustment arrangement includes first adjustment parts with which the carrier can be rotated around a first vertical axis, and second adjustment elements for moving or swivelling the first axis in an arch transverse relative to the symmetry axis of the subject during the rotary motion. The swivel radius and the amount of excursion of this swivel motion are selected so that the perpendicular transillumination direction through the subject gives a constant distance between the subject and the film during the motion of the rotary unit. To accomplish this, the invention includes two separate embodiments with various modifications.