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.. Standard exposure ranges from 75 to 85 kVp, 25 to 40 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.
- Maxillary and lacrimal bones.
Patient preparation
- Verify patient identity.
- Remove glasses, earrings, dentures, hairpins.
- Position patient prone or upright (upright preferred for air-fluid levels).
- Chin against IR; tip of nose ~0.75" away from IR.
- Mentomeatal line (MML) perpendicular to IR.
- No rotation: shoulders and head symmetrical.
- 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
- 75–85
- mAs
- 25–40
- SID
- 40" (102 cm)
- Notes
- For air-fluid level evaluation: take upright (not supine). Suspended respiration.
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 tilt: zygomatic arches symmetrical.
- Maxillary, lacrimal, zygomatic bones, and orbital floor visible.
- Nasal septum visible in midline without rotation.
Common errors / ARRT traps
- 1 Chin not touching IR: petrous ridges project above sinuses.
- 2 MML not perpendicular: distortion of sinus anatomy.
- 3 Rotation: asymmetrical appearance of zygomatic arches.
- 4 Tilt: orbital rims appear at different levels.
- 5 Excessive distance between nose and IR: magnification error.
Clinical indications
- Maxillary sinusitis evaluation (air-fluid level if upright).
- Facial bone fractures: zygomatic arch, orbital floor, Le Fort.
- Foreign body localization in facial area.
- Pre- or post-operative sinus follow-up.
- Evaluation of orbital contents and globe.
Aligned to the 2025 ARRT Content Specifications.