LATERAL PROJECTION - FEMUR

Friday, November 2, 2012

MEDIOLATERAL OR LATEROMEDIAL POSITION


Note: For possible trauma if site of interest is in area of proximal femur, a unilateral trauma hip routine is recommended. For nontrauma lateral of mid-and proximal femur.

Pathology Demonstrated:

  • Mid and distal femur is demonstrated, including knee joint for detection and evaluation of fracture and/or bone lesions.


Technical Factors:

  • IR size - 35 x 43 cm (14 x 17 inches), lengthwise
  • Moving or stationary grid
  • 75 +- 5 kV range
  • Because of anode heel effect, place the hip of the patient at cathode end of x-ray beam.
  • mAs: 7


Shielding:

  • Place lead shield over pelvic area to shield gonads.


Patient Position:

  • Take radiograph with patient in the lateral recumbent position, or supine for trauma patient.


Part Position:
Lateral Recumbent:
lateral view femur
Warning: Do not attemp this position if patient has severe trauma.

  • Flex knee approximately 45 degree with patient on affected side, and align femur to midline of table or IR.
  • Place unaffected leg behind affected leg to prevent overrotation.
  • Adjust IR to include knee joint (lower IR margin should be approximately 2 inches [5 cm] below knee joint). A second IR to include the proximal femur and hip generally will be required on an adult.


Trauma Lateromedial Projection:

  • Place support under affected leg and knee and support foot and ankle in true AP position.
  • Place cassette on edge against medial aspect of thigh to include knee, with horizontal x-ray beam directed from lateral side.


Central Ray:

  • CR perpendicular to femur and IR directed to midpoint of IR
  • Minimum SID of 40 inches (100 cm)


Collimation:

  • Collimate closely on both sides to femur with end collimation to IR borders.


Radiographic Criteria:

Structure Shown:

lateral distal femur
  • Distal two-thirds of distal femur, including the knee joint, is shown.
  • Knee joint will not appear open, and distal margins of the femoral condyles will not be superimposed because of divergent x-ray beam.


Position:

  • True lateral: Anterior and posterior margins of medial and lateral femoral condyles should be superimposed and aligned with open femoropatellar joint space.


Collimation and CR:

  • Femur should be centered to collimation field with knee joint space a minimum of 1 inches (2.5 cm) from distal IR margins.
  • Minimal collimation borders should be visible on proximal and distal margins of IR.


Exposure Criteria:

  • Optimal exposure with correct use of anode heel effect will result in near uniform density of entire femur.
  • No motion is present; fine trabecular markings should be clear and sharp throughout lenght of femur.

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