1. The midsagittal plane of the patients head is perpendicular to the film which touches the anterior aspect of the patientÕs head.
   
   
2. The patientÕs chin touches the film in such a way that a line from external auditory meatus to nasion forms an angle of 37 degrees with the film.
   
   
3. The x-ray beam is directed perpendicular to the film, entering the posterior aspect of the patientÕs head.

[insert diagram]