AP OBLIQUE PROJECTION - MEDIAL (INTERNAL) ROTATION: ELBOW

Thursday, December 29, 2011

Pathology Demonstrated:

  • Fracture and dislocations of the elbow, primarily the coronoid process, and some pathologic processes, such as osteoporosis and arthritis, are shown.


Medial (Internal rotation) Oblique

  • Best visualizes coronoid process of ulna and trochlea in profile


Technical Factor:

  • IR sizr - 24 x 30 cm (10 x 12 inches)
  • Detail screen, tabletop, division in half crosswise
  • Digital IR - use lead masking
  • 60 or add upto 6 kV range


Shielding:

  • Place lead shield over patient's lap to protect gonads.


Patient Position:

  • Seat patient at end of table, with arm fully extended and shoulder and elbow on same horizontal plane.


Part Position:

  • Align arm and forearm with long axis of portion of IR that is being exposed. Center elbow joint to CR and to portion of IR being exposed.
  • Pronate hand into a natural palm-down position and rotate arm as needed until distal humerus and anterior surface of elbow are rotated 45degrees ( while palpating epicondyles to determine a 45degrees rotation of distal humerus).


Cenral Ray:

  • CR perpendicular to IR, directed to mid elbow joint (approximately 2cm [3/4 inch] distal to midpoint of the line between epicondyles as viewed from the x-ray tube)
  • Minimum SID of 40 inches (100 cm)


Collimation:

  • Collimate on four sides to area of interest.


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Radiographic Criteria:

Structure Shown:

  • Oblique view of the distal humerus and proximal radius and ulna is visible.


Position:

  • Long axis of arm should be aligned with side border of IR.
  • A correct 45 degrees medial oblique should visualize the coronoid process of the ulna in profile.
  • Radial head and neck should be superimposed and centered over the proximal ulna.
  • The medial epicondyle and the throchlea should appear elongated and partial profile.
  • The olecranon process should appear seated in the olecranon fossa and the trochlea notch partially open and visualized with the arm fully extended.


Collimation and CR:

  • Collimation should be visible on four sides to area of affected elbow.
  • CR and center of collimation field should be at mid elbow joint.


Exposure Criteria:

  • Optimal density and contrast with no motion should visualized soft tissue detail and bony cortical margins and clear, bony trabecular markings.

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