The five degree rule: optimization of the paranasal sinus examination of children

Customary examination of the paranasal sinuses includes radiographs obtained in the Waters view, PA or AP, and lateral projections. The Waters view is often suboptimal because it does not allow for the progressive enlargement of the maxillary antra during the first six years of life. A model was developed and tested prospectively to tailor the Waters view to the age of the patient. The correction factor of 5 degrees per year of age is most useful in minimizing overlap of the petrous bone and the maxillary sinus.