When performing an AP projection of the humerus how far above the level of the shoulder should the top of the image receptor be placed?

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Citation:

Murphy, A. Shoulder (AP view). Reference article, Radiopaedia.org. (accessed on 08 Sep 2022) //doi.org/10.53347/rID-45849

The shoulder AP view is a standard projection that makes up the two view shoulder series. The projection demonstrates the shoulder in its natural anatomical position allowing for adequate radiographic examination of the entire clavicle and scapula, as well as the glenohumeral, acromioclavicular and sternoclavicular joints of the shoulder girdle. 

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This view helps in visualizing potential fractures or dislocations to the proximal humerus and shoulder girdle in a trauma setting. Additionally, this view is useful in assessing for degenerative diseases which may be seen as calcium deposits in bursal structures, muscles or tendons around the shoulder.

  • patient is preferably erect
  • midcoronal plane of the patient is parallel to the image receptor, in other words, the patient's back is against the image receptor
  • glenohumeral joint of the affected side is at the center of the image receptor
  • affected arm is in a neutral position by the patient side
  • the patient is slightly rotated 5-10° toward the affected side. Therefore, the body of the scapula is laying parallel with the image receptor
  • anteroposterior projection
  • centering point
    • 2.5 cm inferior to the coracoid process, or 2 cm inferior to the lateral clavicle at the level of the glenohumeral joint
  • collimation
    • superior to the skin margins
    • inferior to include one-third of the proximal humerus
    • lateral to include the skin margin
    • medial to include the sternoclavicular joint
  • orientation  
    • landscape
  • detector size
    • 24 cm x 30 cm
  • exposure
    • 60-70 kVp
    • 10-18 mAs
  • SID
    • 100 cm
  • grid
    • yes (this can vary departmentally)
  • the entire clavicle is visualized alongside the glenoid cavity and scapula in the AP position
  • a slight overlap of the humeral head with the glenoid
  • no foreshortening of the scapular body (as per the patient rotation discussed in the positioning)

The technical factors of this examination are not particularly demanding, and there is not much room for positioning error other than over or under rotation to compensate for the scapular body.

An open glenohumeral joint is a sign of over rotation toward the affected side. This results in a more AP glenoid view, and although diagnostically relevant to shoulder pathology, it is not an accurate representation of the surrounding structures.

References

Related articles: Imaging in practice

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How far above the humeral head should the upper margin of the IR be placed for a lateral projection of the humerus?

Positioning for a lateral projection of the humerus Place the top margin of the cassette approximately 1½ inches (3.8 cm) above the level of the head of the humerus. Unless contraindicated by possible fracture, internally rotate the arm, flex the elbow approximately 90°, and place the patient's hand on their hip.

What is the best position of the patient when imaging fracture of the humerus AP )?

humerus and resulting radiograph. The patient is positioned laterally with the unaffected arm raised above the head. This position is 90° from the AP projection and can be performed sitting or recumbent. Patients who have humeral fractures frequently present to the radiology department in a sit- ting position.

Where is the central ray directed for an AP projection of the humerus?

Central ray: The central ray should be directed to the scapulohumeral joint perpendicular to the image receptor. For an AP Axial, a cephalic angle of 35 degrees.

What are the proper patient instructions for the AP projection of the shoulder?

XR 103 final exam.

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