MEDIOLATERAL OR LATEROMEDIAL POSITION
Pathology Demonstrated:
- Fracture and/or dislocation of the phalanges of the digits in question are demonstrated. Some pathologies such as osteoarthritis and gouty arthritis (gout may be evident, especially in the first digit.
Technical Factor:
- IR size - 18 x 24 cm (8 x 10 inches), crosswise
- Divide in thirds, crosswise
- Detail screen, tabletop
- Digital IR - use lead masking
- 50 to 60 kV range
- mAs 2
Shielding:
- Place lead shield over pelvic area to shield gonads.
Patient and Part Position:
Lateral Great Toe |
- Rotate affected leg and foot medially (lateromedial) for first, second, and third digits and laterally (mediolateral) for fourth and fifth digits.
- Adjust cassette to center and align long axis of toe in question to CR and to long axis of portion of IR being exposed.
- Ensure that IP joint or PIP joint in question is centered to CR.
- Use tape, gauze, or tongue blade to flex and separate unaffected toes to prevent superimposition.
Central Ray:
Lateral Second Toe |
- CR perpendicular to IR
- CR directed to interphalangeal joint for first and to proximal interphalangeal joint for second to fifth digits.
- Minimum SID of 40 inches (100 cm)
Collimation:
- Collimate closely on four sides to affected digit.
CR and DR:
- Close collimation and lead masking are important over unused portions of image plate to prevent fogging from scatter radiation to the hypersensitive image plate or receptor.
Structure Shown:
- Phalanges of digits in question should be seen in lateral position free of superimposition by other digits, if possible. (When total separation of toes is not possible, especially third to fifth digits, the distal phalanx at least should be separated and the proximal phalanx visualized through superimposition structures.)
Position:
- Long axis of digits is aligned to long axis of portion of IR being used.
- True lateral of digits will demonstrate increased concavity on the anterior surface of the distal phalanx and the posterior surface of the proximal phalanx.
- Opposing surface of each phalanx will appear straighter.
Collimation and CR:
Lateral Great Toe |
- Collimation borders should be visible on all four sides with the center (CR) at the appropriate interphalangeal joint.
- Interphalangeal joints should appear open and unobstructed.
- The MTP joint should be visualized even if superimposed.
Exposure Criteria:
- No motion as evidenced by sharply defined cortical margins of the bone and detailed bony trabeculae.
- Optimal contrast and density will allow visualization of bony cortical margins and trabeculae and soft tissue structures.