AP PROJECTION: HUMERUS

Thursday, January 12, 2012

Warning:
  • Do not attempt to rotate arm if fracture or dislocation is suspected.


Pathology Demonstrated:

  • Fracture and dislocation of the humerus, as well as other pathologic processes such as osteoporosis and arthritis, are demonstrated.


Technical Factor:

  • IR size - lengthwise (large enough to include entire humerus)
  • For larger patient, 35 x 43 cm (14 x 17 inches) may be needed to place cassette diagonally to include both joints
  • For smaller patient, 30 x 35 cm (11 x 14 inches)
  • Moving or stationary grid (non-grid, detail screen for smaller patient)
  • 70+- 6 kV range


Shielding:

  • Secure or place lead shield over pelvic area.
AP Humerus Erect


Patient Position:

  • Position patient erect or supine. Adjust height of cassette so that shoulder and elbow joints are equidistant from ends of IR.


Part Position:

  • Rotate body towards affected side as needed to bring shoulder and proximal humerus in contact with cassette.
  • Align humerus with long axis of IR, unless diagonal placement is needed to include both shoulder and elbow joints.
  • Extend hand and forearm as far as patient can tolerate.
  • Abduct arm slightly and gently supinate hand so that epicondyles of elbow are equidistant from IR.
AP Supine Note that the hand is supinated


Central Ray:

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


Collimation:

  • Collimate on sides to soft tissue borders of humerus and shoulder. (Lower margin of collimation field should include the elbow joint and about 2.5 cm [1 inch] minimum of proximal forearm.)


Respiration:

  • Suspend respiration during exposure


..................................................................................
Radiographic Criteria:
AP Humerus Erect

Structure Shown:

  • AP projection of the entire humerus, including the shoulder and elbow joints, is visible.


Position:

  • Long axis of humerus should be aligned with long axis of IR.

True AP projection is evidenced at proximal humerus by the following:

  • Greater tubercle is seen in profile laterally.
  • Humeral head is partially seen in profile medially, with minimal superimposition of the glenoid cavity.
  • Distal Humerus: Lateral and medial epicondyles both are visualized in profile.


Collimation and CR:

  • Collimation borders are visible at the skin margins along the length of the humerus, with minimal collimation at both ends to ensure that essential joint anatomy is included.
  • CR and center of collimation field should be to the approximate midpoint of the humerus.


Exposure Criteria:

  • Optimal density and contrast with no motion visualize sharp cortical margins and clear, bony trabecular markings at both proximal and distal portions of the humerus.

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