Radiography Projections of Facial Bones and Sinuses

Submentovertex Projection

• Projection of the sphenoid sinuses through the open mouth, demonstrating an axial image
• Central Ray (CR) is perpendicular to the line extending from the sella turcica to the center of the open mouth at 30° caudad to the Mid-Sagittal Plane (MSP)

PNS Submentovertex Projection

• Projection of the sphenoid, ethmoid, and maxillary sinuses, demonstrating a basal image
• CR is perpendicular between the angles of the mandible

Facial Lateral Projection

• Projection of the zygoma, centered to the Mid-Lateral Line (MLT)
• CR is perpendicular to mid-zygoma, midway between the outer canthus and the External Auditory Meatus (EAM)
• Useful for demonstrating depressed fractures of the frontal sinus

Facial Waters Projection

• Projection of the facial bones, demonstrating an axial image
• Best single projection for demonstrating the entire facial bone
• Petrous ridge is projected below the maxillary sinus
• Useful for demonstrating fractures of the orbit and nasal wings

Modified Waters Projection

• Prone position, with the patient's head resting on the chin and nose
• Left Median Line (LML) is perpendicular to the table, and the Occipital Mandibular Line (OML) forms an angle of 55° with the film
• CR is perpendicular to the acanthion
• Demonstrates facial bones with less axial angulation, with petrous ridges projected into the lower half of the maxillary sinuses
• Best demonstrates a more direct view of the orbital rim compared to the Waters projection

Facial Bones AP Axial Reverse Waters Projection

• Supine position
• Inferior Oculo-Mental Line (IOML) is perpendicular to the Image Receptor (IR)
• CR is 30° cephalad, entering the face or slightly below the lips, and exiting 2 inches above the inion
• CR must be parallel to the Mid-Mental Line (MML)
• Demonstrates an axial position of the superior facial bone, similar to the Waters projection, although the structures are magnified

Nasal Lateral (Soft Tissue Lateral) Projection

• CR is perpendicular to ½ inch inferior to the nasion

Paranasal Sinuses

• Large air-filled cavities that should be radiographed in an erect/upright position to demonstrate the presence of air-fluid level and differentiate between shadows caused by fluid and those caused by other pathologic conditions.
• Patient must be in an erect position for at least 5 minutes before examination.

Types of Paranasal Sinuses

• Frontal Sinuses: located in the frontal (cranial) bone.
• Ethmoid Sinuses: located in the ethmoid (cranial) bone.
• Maxillary Sinuses: located in the maxillary (facial) bone.
• Sphenoid Sinuses: located in the sphenoid (cranial) bone.

Projections for Paranasal Sinuses

Lateral Projection

• CR horizontally directed 1 inch posterior to outer canthus.
• Best projection to demonstrate all 4 sinuses.
• Demonstrates the sphenoid sinus, which is of primary importance in this projection.

Caldwell's Method

• CR 15° caudad to nasion.
• Best projection to demonstrate the frontal sinuses and anterior ethmoidal sinuses.
• Petrous ridge is projected into the lower 1/3 of the orbits.

Parietoacanthial Projection (Water's Method)

• Patient's head is resting on the chin.
• MML is perpendicular to IR.
• OML forms an angle of 37° with the plane of the film.
• Tip of the nose is 1/2 inch from the image receptor.
• CR is directed to acanthion.
• Best projection to demonstrate the maxillary sinuses above the petrous ridge.
• Useful for demonstrating the foramen rotundum and the petrous pyramids below the maxillary sinuses.

Parietoacanthial Open-Mouth Projection (Water's Method)

• Demonstrates the sphenoid sinuses through the open mouth.
• The open mouth projection removes the upper teeth from direct superimposition of the sphenoid.

Axial Transoral Projection (Pire Method)

• Head is resting on the nose and chin.
• Patient is instructed to phonate "ah" softly during exposure.
• Useful for demonstrating the sphenoid sinuses.