Shoulder Transthoracic Lateral is a radiography positioning projection of the Upper Extremity. Lateral erect, affected shoulder against IR. Breathing technique. SID 40". The centering point is located surgical neck of the affected humerus, with the affected shoulder against the IR and the lateral thorax included. The central ray is horizontal, perpendicular to the IR, through the thorax to the surgical neck. (Alternative: 10-15 degrees cephalad if the opposite shoulder cannot be raised.). Image-quality criteria include proximal humerus projected in true lateral profile, proximal humeral shaft outlined anterior to the thoracic vertebrae. A sample technique is 85 kVp with DR 28 or CR 56 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Proximal humerus in true lateral profile.
- Scapula superimposed over the thoracic spine.
- Shoulder joint space.
- Humeral head with the greater and lesser tubercles.
- Thoracic spine and ribs.
- Lung markings (blurred by breathing technique).
Patient preparation
- Verify patient identity using two identifiers.
- Remove watches, bracelets, and radiopaque items from shoulder.
- Position patient erect, lateral to the IR.
- Affected shoulder positioned against the IR, arm at the side in a neutral position.
- Raise the opposite arm over the head, elevating that shoulder out of the field.
- If the patient can cooperate, instruct on gentle, shallow breathing during the exposure; otherwise expose on full inspiration.
Position & centering point
Surgical neck of the affected humerus, with the affected shoulder against the IR and the lateral thorax included.
Central ray
Horizontal, perpendicular to the IR, through the thorax to the surgical neck. (Alternative: 10-15 degrees cephalad if the opposite shoulder cannot be raised.)
Exposure / technique
- kVp
- 85
- mAs
- DR 28 / CR 56
- SID
- 40" (102 cm)
- Notes
- Erect technique. ARRT lists this projection under Humerus in both the 2022 and 2027 outlines; Bontrager gives it for the humerus and the shoulder. Breathing: Bontrager prefers gentle, short, shallow breaths if the patient can cooperate, otherwise full inspiration; Merrill's uses full inspiration, or slow deep breathing if the patient can hold still. Sample technique: DR 28 / CR 56 mAs at 85 kVp, 40 in SID, for a 40 cm part. Adjust for your equipment.
kVp and mAs are sample values. Use caution when applying them in your department.
Image-quality criteria
- Proximal humerus projected in true lateral profile.
- Proximal humeral shaft outlined anterior to the thoracic vertebrae.
- Humeral head and glenoid relationship shown, without the opposite shoulder superimposed.
- Proximal humerus seen through the thorax, with ribs and lung blurred by breathing.
- Thorax included but lungs intentionally blurred.
- Collimation: four sides to the area of interest (Bontrager); 10 x 12 inches (Merrill's).
Common errors
- 1 Affected shoulder positioned away from the IR instead of against it.
- 2 Insufficient breathing blur still shows sharp lung detail.
- 3 Thorax neither in true lateral nor with the unaffected shoulder rotated slightly anterior: vertebrae overlap the humerus.
- 4 CR not at the level of the affected surgical neck.
- 5 Opposite shoulder not elevated enough; if pain prevents it, angle the CR 10 to 15 degrees cephalad.
Clinical indications
- Shoulder trauma when the arm cannot be rotated or abducted because of injury.
- Posterior or anterior humeral head dislocation evaluation.
- Proximal humeral fracture with displacement.