1. The midsagittal plane of the patient's head is vertical.
   
   
2. The patient's head is tipped posteriorly.
   
   
3. The film is placed in the patient's mouth so that the side to be exposed is facing the mandibular arch. The patient closes on the film.
   
   
4. The central ray of the x-ray beam is directed superiorly in the midsagittal plane to the center of the film through the chin.
   

[insert diagram]