PARIETOACANTIAL TRANSORAL PROJECTION : SINUSES

OPEN MOUTH WATERS METHOD

Pathology Demonstrated:

• Inflammation conditions (sinusitis, secondary osteomyelitis) and sinus polyps are shown.

Technical Factors:

• IR size - 18 x 24 (8 x 10 inches). lengthwise
• Moving or stationary grid
• 70 to 80 kV range
• small focal spot
• mAs 28

Patient Position on Sinusitis x-ray:

• Remove all metallic or plastic objects from head and neck.
• Position patient erect. see note.

Part Position:

Parietoacantial Transoral Projection

• Extend neck, packing chin and nose against table or upright Bucky surface
• Adjust head until OML forms a 37° angle with IR (MML will be perpendicular with mouth closed).
• Position the MSP perpendicular to the midline of the grid or the table or upright Bucky surface.
• Ensure no rotation or tilt.
• Instruct patient to open mouth by instructing to "drop jaw without moving head." (Mento Meatel Line (MML) is no longer perpendicular.)
• Center IR to CR and to acanthion.

Central Ray:

• Align a horizontal CR perpendicular to the IR.
• Center CR to exit at acanthion.
• Minimum SID is 40 inches (100 cm)

Collimation:

• Collimation on all sides to area of sinus cavities.

Respiration:

• Suspend respiration during exposure.

Radiographic Criteria:

Structures Shown:

• Maxillary sinuses with the inferior aspect visualized, free from superimposition alveolar processes and petrous ridges, the inferior orbital rim, an oblique view of the frontal sinuses, and the sphenoid sinuses visualized through the open mouth.

Position:

• No rotation of the cranium is indicated by the following:
• Equal distance from the midsagittal plane (identified by the bony nasal septum) to the outer orbital margin on both sides.
• Equal distance from the lateral orbital margins to the outer table of the skull on both sides.
• Accurate extension of the neck demonstrating petrous ridges below the maxillary sinuses.

Collimation and Central Ray:

• Collimated field included the frontal maxillary, and sphenoid sinuses, with the maxillary sinuses at the center.

Exposure Criteria:

• Density and contrast are sufficient to visualize the maxillary and sphenoid sinuses.
• Sharp bony margins indicate no motion.