Any apparatus that is to perform properly the work of sinus roentgenography should fulfil the following requirements:
1. It must permit the taking of roentgenograms of the head with the patient in the sitting position.
2. It must be possible to direct the ray at any desired angle, with provision for indicating the angle of inclination. It should be particularly easy to use the horizontal ray.
3. It must be possible to set the casette-holder at any desired angle with the ray, with provision for indicating the angle.
4. The tube and cone must be fixed in relation to the casette-holder so that centering of the ray on the film is automatic regardless of the position of the apparatus.
5. It must be possible to immobilize the patient's head well, so that long exposures may be taken.
6. The apparatus must be capable of making stereoscopic exposures in any position.