Cranium and Facial Bone Projections

Lateral Skull

Part Position: Patient in true lateral; IPL perpendicular to IR; IOML parallel to bottom edge.

Central Ray: Perpendicular, entering 2 inches superior to EAM.

Collimation: Include entire skull from vertex to base.

Anatomy of Interest: Superimposed cranial halves, sella turcica, anterior/posterior clinoid processes.

PA Skull

Part Position: Forehead and nose against IR; OML perpendicular to IR.

Central Ray: Perpendicular to exit at nasion.

Collimation: Include entire skull and frontal bone.

Anatomy of Interest: Frontal bone, petrous ridges filling the orbits.

PA Axial (Caldwell)

Part Position: Forehead and nose on IR; OML perpendicular to IR.

Central Ray: Angled 15° caudad to exit at nasion.

Collimation: Include frontal bone and orbital structures.

Anatomy of Interest: Petrous pyramids fill 1/3 of the lower orbits, Orbital rims, maxillae, nasal septum, zygomatic bones, anterior cranial floor.

AP Skull

Part Position: Back of head against IR; OML perpendicular.

Central Ray: Perpendicular to nasion.

Collimation: Include entire skull and frontal bone.

Anatomy of Interest: Frontal bone, petrous ridges filling the orbits (similar to PA Skull).

AP Axial (Towne)

Part Position: Back of head on IR; OML perpendicular (or IOML if needed).

Central Ray: 30° caudad to OML (or 37° to IOML), entering 2.5 inches above glabella and passing through foramen magnum.

Collimation: Include occipital bone and foramen magnum.

Anatomy of Interest: Occipital bone, petrous pyramids, dorsum sellae, foramen magnum.

NOTES: When trying to visualize the entire foramen magnum, CR may be increased from 40 to 60 degrees to the IOML.

PA Axial (Haas)

Part Position: Forehead and nose on IR; OML perpendicular.

Central Ray: 25° cephalad to OML, entering 1.5 inches below inion and exiting 1.5 inches superior to nasion.

Collimation: Include occipital region and foramen magnum.

Anatomy of Interest: Occipital bone, dorsum sellae within foramen magnum (reverse of Towne).

SMV (Schuller Method)

Part Position: IOML parallel to IR; vertex in contact with IR.

Central Ray: Perpendicular to IOML, entering 3/4 inch anterior to EAM (level of sella turcica).

Collimation: Include skull base.

Anatomy of Interest: Foramen ovale and spinosum, mandible, sphenoid and ethmoid sinuses.

Lateral Facial Bones

Part Position: Head in true lateral; IPL perpendicular; IOML parallel to bottom of IR.

Central Ray: Perpendicular to zygoma (midway between outer canthus and EAM).

Collimation: Include from top of orbits to mandible.

Anatomy of Interest: Facial bones in profile, superimposed zygomatic bones, orbital roofs.

Parietoacanthial (Waters)

Part Position: Chin on IR; MML perpendicular; OML forms 37° angle with IR.

Central Ray: Perpendicular to exit at acanthion.

Collimation: Include orbits to maxillae.

Anatomy of Interest: Maxillae, orbits, zygomatic arches, nasal septum.

Comparison Notes: Compared to PA Skull: CR is more inferior (to acanthion vs. nasion) and head is extended to demonstrate maxillary sinuses clearly.

NOTES: Patients must angle themselves to 55 degrees to perform the modified waters. This is good for visualizing the orbital floor.

Acanthioparietal (Reverse Waters)

Part Position: Supine; extend chin so MML is perpendicular to IR.

Central Ray: Perpendicular to enter at acanthion.

Collimation: Include entire facial bones.

Anatomy of Interest: Same as Waters but in trauma patients.

Comparison Notes: Same angle and CR location as Waters but reversed direction.

PA Axial for Facial Bones (Caldwell)

Part Position: Forehead and nose on IR; OML perpendicular.

Central Ray: 15° caudad to exit at nasion.

Collimation: Include frontal bone and orbits.

Anatomy of Interest: Orbital margins, nasal septum, zygomatic bones, maxillae.

Comparison Notes: Same CR as Caldwell for cranium, but collimation focuses more on facial structures.

NOTES: Angel CR to 30 degrees for orbital rims.

Lateral Nasal Bones

Part Position: IPL perpendicular, IOML parallel to IR; true lateral.

Central Ray: Perpendicular to 1/2 inch distal to nasion.

Collimation: Include nasal bones and soft tissue nose.

Anatomy of Interest: Nasal bones in profile, anterior nasal spine.

SMV for Zygomatic Arches

Part Position: Vertex on IR; IOML parallel to IR.

Central Ray: Perpendicular to IOML, entering at mid-throat, 1 inch posterior to outer canthi.

Collimation: Include both zygomatic arches.

Anatomy of Interest: Bilateral zygomatic arches, free of superimposition.

Comparison Notes: Same positioning and CR as SMV for cranium, but collimation focuses on zygomatic arches.

Tangential Zygomatic Arches

Part Position: IOML parallel to IR; rotate head 15° toward side examined and tilt 15° away.

Central Ray: Perpendicular to IOML, centered to arch of interest.

Collimation: Include only the arch of interest.

Anatomy of Interest: Unilateral zygomatic arch, free of superimposition.

AP Axial (Modified Towne) for Zygomatic Arches

Part Position: Back of head on IR; OML or IOML perpendicular.

Central Ray: 30° caudad to OML (or 37° to IOML), entering 1 inch above nasion.

Collimation: Include both arches.

Anatomy of Interest: Bilateral zygomatic arches.

Comparison Notes: Same technique as Towne for cranium, but CR is centered higher (1 inch above nasion vs. 2.5 inches above glabella).

Lateral for Sinuses

Part Position: Head in true lateral; IPL perpendicular; IOML perpendicular to front edge of IR.

Central Ray: Horizontal, perpendicular to 1/2-1 inch posterior to outer canthus.

Collimation: Include all four sinus groups.

Anatomy of Interest: All sinus groups, especially sphenoid; superimposed orbital roofs.

Comparison Notes: Similar to lateral skull, but horizontal beam used for air-fluid levels.

PA Axial (Caldwell) for Sinuses

Part Position: Forehead and nose on IR; OML forms 15° angle with IR (head slightly extended).

Central Ray: Horizontal, exiting at nasion.

Collimation: Include frontal and ethmoid sinuses.

Anatomy of Interest: Frontal sinuses above frontonasal suture, anterior ethmoid air cells.

Comparison Notes: CR is horizontal rather than angled 15° caudad like in cranium/facial Caldwell.

Waters for Sinuses

Part Position: Chin on IR; MML perpendicular to IR; OML forms 37° angle with IR.

Central Ray: Horizontal, exiting at acanthion.

Collimation: Include maxillary sinuses and surrounding structures.

Anatomy of Interest: Maxillary sinuses, inferior orbital rim, nasal septum.

Comparison Notes: Same position as Waters for facial bones but emphasizes maxillary sinuses with horizontal CR.

SMV for Sinuses

Part Position: Vertex on IR; IOML parallel to IR; neck extended.

Central Ray: Horizontal, perpendicular to IOML, entering msp at level of sella turcica

Collimation: Include sphenoid and ethmoid sinuses.

Anatomy of Interest: Sphenoid and ethmoid sinuses, nasal fossae.

Comparison Notes: Same as SMV for cranium/facial bones, but beam is horizontal for air-fluid levels.

PA for Mandible

Part Position: Forehead and nose on IR; OML perpendicular to IR.

Central Ray: Perpendicular to exit the acanthion.

Collimation: Include mandible from condyles to symphysis.

Anatomy of Interest: Mandibular rami and lateral body.

PA Axial for Mandible

Part Position: Forehead and nose on IR; OML perpendicular to IR.

Central Ray: 20-25° cephalad, exiting at acanthion.

Collimation: Include rami and TMJs.

Anatomy of Interest: Mandibular rami and condylar processes.

Axiolateral Oblique for Mandible

Part Position: Head in true lateral then rotated 30° toward IR (for body); IPL perpendicular to IR; extend neck.

Central Ray: 25° cephalad angle, directed to mandibular region of interest.

Collimation: Include side of mandible closest to IR.

Anatomy of Interest: Ramus (0°), body (30°), symphysis(45°); general survey (10-15°).

AP Axial for TMJs

Part Position: Back of head against IR; OML perpendicular to IR.

Central Ray: 35° caudad, centered 3 inches above nasion to pass through TMJs.

Collimation: Include TMJs bilaterally.

Anatomy of Interest: Condyles of mandible, mandibular fossae of temporal bones.

NOTES: Mouth closed = min. Superimposition of the petrosa on condyles. Mouth open = condyle & TMH below petrosa.

Axiolateral Oblique for TMJs

Part Position: Head in true lateral, rotate skull 15° toward IR; IPL perpendicular, AML parallel to transverse axis of IR.

Central Ray: 15° caudad, entering 1.5 inches superior to upside EAM.

Collimation: Include TMJ of interest.

Anatomy of Interest: Open and closed views of TMJ, mandibular condyle, and fossa.

Lateral for Orbits

Part Position: Head in true lateral; IPL perpendicular to IR; IOML perpendicular to front edge of IR.

Central Ray: Perpendicular to outer canthus.

Collimation: Include entire orbital region.

Anatomy of Interest: Superimposed orbital roofs, orbital margins, adjacent facial bones.

PA Axial for Orbits

Part Position: Forehead and nose on IR; OML perpendicular to IR.

Central Ray: 30° caudad to exit at mid orbits.

Collimation: Include orbits and surrounding structures.

Anatomy of Interest: Orbital rims, orbital floors.

Parietoacanthial for Orbits (Modified Waters)

Part Position: Chin on IR; LML perpendicular; OML forms 50° angle with IR.

Central Ray: Perpendicular to exit at mid orbits.

Collimation: Include orbits bilaterally.

Anatomy of Interest: Orbital floors (blowout fractures), rim, and maxillae.