W10 - Nasal Bones, Orbits

Positioning - PA Waters Nasal Bones

• perp

• exits at acanthion

• 122cm

• suspend

• MML perp to IR, OML 37 from IR

• bilateral outer canthus, supraorbital → upper lip edge

Critique - PA Waters Nasal Bones

Structures: nasal, frontonasal suture, maxillae, ant nasal spine

Positioning - LAT Nasal Bones

• perp

• ½ inch inf to nasion

• 122cm

• suspend

• IOML // IR, IPL perp to IR

Critique - LAT Nasal Bones

Structures: nasal bones, ST nose, frontonasal suture, anterior nasal spine

Clinical Indications of Orbital Exams

• Pre-MRI

• Trauma

• FB

FB Localization - Orbits

multiple projections with only eye movement changes (neutral, up, down)

Positioning - PA Axial Orbits

• perp or 30 caudal

• mid orbits

• 122cm

• suspend

• raise OML 30 from perp beam, OML perp to IR; instruct pt to stare at a fix point or close eyes

Critique - PA Axial Orbits

• BTP: petrous ridges below the infraorbital rim

• no rotation or tilt

• Structures: full orbital rims

Positioning - Modified PA Waters Orbits

• perp

• mid orbits 

• SID

• suspend

• FB = OML 50 from IR

• Trauma = OML 55 from IR (to visualize the orbital floor more)

Critique - Modified PA Waters Orbits

• entire orbits

• petrous seen mid maxillary sinus

• no rotation or tilt

• IQ: orbital floor seen

Positioning - LAT Orbits

• perp

• outer canthus

• 122cm

• suspend

• IOML // IR, IPL perp to IR, instruct pt to stare at a fixed point

Collimation for LAT Orbits

• acanthion → 1.5” ant to EAM

• supraorbital rims → acanthion