PA Axial Projection: Facial Bones (Caldwell Method) and AP axial (Towne's method) Flashcards
What are the technical factors for the Caldwell Method?
Minimum SID: 40 inches (102 cm)
IR size: 18 × 24 cm (8 × 10 inches), or 24 × 30 cm (10 × 12 inches), lengthwise
Grid
Analog: 70 to 80 kV range
Digital systems: 75 to 85 kV range
How should the part be positioned for the Caldwell Method?
- Tuck chin, bringing OML perpendicular to IR.
- Align MSP perpendicular to midline of grid or table/imaging device surface.
- Ensure no rotation or tilt of the head.
What is the patient position for the Caldwell Method?
- Remove all metallic or plastic objects from head and neck.
- The patient should be erect or prone, with the nose and forehead resting against the tabletop.
What is the central ray (CR) alignment for the Caldwell Method?
- Angle CR 15° caudad, to exit at nasion. Center CR to IR.
what is the central alignment if the orbital floors are the area of interest.
- Use a 30° caudad angle to project the petrous ridges below the IOM if the orbital floors are the area of interest.
What should the respiration instructions be for the Caldwell Method?
Suspend respiration
What are the technical factors for the Towne Method?
Minimum SID: 40 inches (102 cm)
IR size: 18 × 24 cm (8 × 10 inches), lengthwise
Grid
Analog: 70 to 80 kV range
Digital systems: 75 to 85 kV range
What are the clinical indications for the Towne Method?
- Fractures,
- Neoplastic or inflammatory processes of condyloid processes of the mandible.
How should shielding be applied in the Towne Method?
Shield radiosensitive tissues outside the region of interest.
What is the patient position for the Towne Method
- Remove all metallic or plastic objects from head and neck.
- The patient should be erect or supine, with the posterior skull resting against the table or upright imaging device surface.
How should the part be positioned for the Towne Method?
- Tuck chin, bringing OML perpendicular to IR, or place IOML perpendicular and add 7° to CR angle.
- Align MSP perpendicular to midline of grid or table/upright imaging device surface to prevent head rotation or tilt.
What is the central ray (CR) alignment for the Towne Method?
- Angle CR 35° to 42° caudad.
- Center CR to glabella and IR to CR.
what should be the centering point if the TM fossae are of interest.
If the TM fossae are of interest, angle 40° to OML to reduce superimposition of TM fossae and mastoid portions of the temporal bone.
What should the respiration instructions be for the Towne Method?
Suspend respiration during exposure.
What anatomy should be demonstrated in the Towne Method?
Condyloid processes of the mandible and TM fossae.
