- If patient has possible wrist trauma, do not attempt this position before routine wrist series has been completed and evaluated to rules out possible truama of distal forearm and/or wrist
Pathology Demonstrated:
- Fracture of the scaphoid are demonstrated. Non-displaced fractures may require additional projections on a CT scan of the wrist.
Technical Factors:
- IR size - 18 x 24 cm (8 x 10 inches)
- Division in half crosswise
- Detail screen tabletop
- Digital IR - use lead masking
- 60 or add up to 6kV range
Shielding:
- Place lead shield over patient's lap to shield gonads.
Patient Position:
- Seat patient at end of table, with wrist and hand on cassette, palm down, and shoulder, elbow, and wrist on same horizontal plane.
Part Position:
- Position wrist as for PA projection - palm down and hand and wrist aligned with center of long axis of portion of IR being exposed, with scaphoid centered to CR.
- Without moving forearm, gently evert hand (move toward ulnar side) as far as patient can tolerate without lifting or rotating distal forearm.
Note:
See terminology, Chapter 1, for explanation of ulnardeviation versus radial deviation.
- Angle CR 10 to 15degrees proximally, along long axis of forearm and toward elbow. (CR angle should be perpendicular to long axis of scaphoid.)
- Center CR to scaphoid. (Locate scaphoid at a point 2 cm [3/4 inch] distal and medial to radial styloid process.)
- Minumum SID is 40 inches (100cm)
Collimation:
- Collimate on four sides to carpal region.
Note:
- Obscure fracture of scaphoid may require several projections taken with different CR angles. Rafert and long (1991)* describe a four projection series with the CR angled proximally 0degree, 10degrees, 20degrees, and 30degrees.
Radiographic Criteria:
Structure Shown:
- Distal radius and ulna, carpals, and proximal metacarpals are visible.
- Scaphoid should be demonstrated clearly without foreshortening, with adjacent carpal interspaces open (evidence of CR angle).
Position:
- Long axis of risk and forearm should be aligned with side boarder of IR
- Ulnar deviation should be evident by the angle of the long axis of the metacarpals to that of the radius and ulna.
- No rotation of the wrist is evidenced by appearance of distal radius and ulna, with minimal superimposition of distal radioulnar joint.
Collimation and CR:
- Collimation should be visible on four sides to area of affected wrist.
- CR and center of collimation field should be to the scaphoid.
Exposure Criteria:
- Optimal density and contrast with no motion visualize the scaphoid borders and clear, sharp bony trabecular markings.
