Facial Bones Parietoacanthial (Waters) is a radiography positioning projection of the Skull. Waters method. Maxillary sinuses, facial bones. MML perpendicular to IR. The centering point is located CR exits at acanthion. MML perpendicular to IR, chin touching IR. The central ray is CR perpendicular to IR. Centered to exit at the acanthion. Image-quality criteria include petrous ridges projected just below maxillary sinus floor, maxillary sinuses clearly visualized without overlap. A sample technique is 85 kVp with DR 8 or CR 16 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Maxillary sinuses with clear floor and air-fluid level.
- Zygomatic bones, zygomatic arches bilaterally.
- Orbital floors, orbital rims without overlap.
- Petrous ridges projected below sinus floor.
- Nasal septum and nasal fossae.
- Maxillae.
Patient preparation
- Trauma patient: rule out cervical spine fracture, subluxation or dislocation before moving or manipulating the head or neck.
- Verify patient identity.
- Remove glasses, earrings, dentures, hairpins.
- Position patient prone or upright (upright preferred for air-fluid levels).
- Chin against IR (Bontrager, facial Waters). Merrill's puts the nose about 3/4 inch from the IR; Bontrager's sinus Waters rests chin and nose.
- Mentomeatal line (MML) perpendicular to IR.
- MSP perpendicular to the midline of the grid, with no head rotation or tilt.
- Suspend respiration during exposure.
Position & centering point
CR exits at acanthion. MML perpendicular to IR, chin touching IR.
Central ray
CR perpendicular to IR. Centered to exit at the acanthion.
Exposure / technique
- kVp
- 85
- mAs
- DR 8 / CR 16
- SID
- 40" (102 cm)
- Notes
- For air-fluid level evaluation: take upright (not supine). Suspended respiration. Sample technique: DR 8 / CR 16 mAs at 85 kVp, 40 in SID, for a 24 cm part. Adjust for your equipment.
kVp and mAs are sample values. Use caution when applying them in your department.
Image-quality criteria
- Petrous ridges projected just below maxillary sinus floor.
- Maxillary sinuses clearly visualized without overlap.
- No rotation: equal distance from lateral skull margin to mid-orbit.
- No rotation or tilt: orbits and maxillary sinuses symmetric on each side (Merrill's).
- Maxillae, zygomatic bones, and inferior orbital margins visible.
- Nasal septum visible in midline without rotation.
Common errors
- 1 Too little neck extension projects the petrous ridges over the inferior maxillary sinuses.
- 2 Rotation: asymmetrical appearance of zygomatic arches.
- 3 Tilt: orbits and maxillary sinuses not symmetric.
- 4 Too much neck extension foreshortens the maxillary sinuses and hides the antral floors.
Clinical indications
- Maxillary sinusitis evaluation (air-fluid level if upright).
- Facial bone fractures: zygomatic arch, orbital floor, Le Fort.
- Foreign bodies in the eye.
- Neoplastic or inflammatory processes of the facial bones.