PA AXIAL PROJECTION FACIAL BONES

CALDWELL METHOD | PA AXIAL FOR FACIAL BONE X-RAY

Pathology Demonstrated:

• Fracture and neoplastic or inflammatory processes of the facial bones are shown.

Technical Factors:

• IR size is 24 x 30 cm (10 x12 inches), lengthwise or film size 18 x 24 cm (8 x 10 inches)
• Image receptor size varies depending on the patient.
• Moving or stationary grid.
• 70 to 80 kV range.
• Small focal spot.
• mAs 18

Erect Caldwell OML perpendicular

Patient Position:

• Rest patient's nose and forehead against table top.
• Tuck chin, bringing OML perpendicular to image receptor.
• Align MSP perpendicular to middle of grid or table or bucky surface. Ensure no rotation or tilt of head.

Central Ray of Caldwell Method:

• Angle Central Ray 15 degrees caudad, to exit at nasion. If area of interest is the orbital floors, use a 30 degree caudad angle to project the petrous ridges below the inferior orbital margin.
• Central Ray must be centered to IR.
• Ensure minimum SID of 40 inches (100 cm)

Collimation:

• Collimate on all sides to facial bones.

Respiration:

• Suspend respiration.

Radiographic Criteria when performing the Caldwell Method:

PA Axial, Caldwell Method 15 degree CR

Structure Shown:

• Orbital rim, maxillae, nasal septum, zygomatic bones and anterior nasal bone spine.

Position:

• Correct patient position / CR angulation is indicated by petrous ridges projected into the lower 1/3 of orbits with 15 degrees caudad central ray. If the orbit floors are the area of interest, the 30 degree caudad angle projects the petrous ridges below the inferior margins of the orbit.
• No rotation of cranium is indicated by equal distance from midlateral orbital margin to the outer skull margin on each side
• Superior Orbital fissures are symmetric.

Collimation and Central Ray:

• The inferior orbital rim is located at the center of the image.
• The collimated field includes the entire orbital margin and maxillae.

Exposure Criteria:

• Comtrast and density are sufficient to visualize maxillary region and orbital floor.
• Sharp bony margins indicate no motion.