Shoulder Scapular Y is a radiography positioning projection of the Upper Extremity. Lateral or oblique erect position, arm abducted. CR perpendicular to scapular Y. SID 40". The centering point is located the intersection of the scapular body, spine, and acromion (the y junction), with arm abducted.. The central ray is perpendicular to the scapular y formed by the scapular body, spine, and acromion.. Image-quality criteria include scapular y clearly formed by scapular body, spine, and acromion., humeral head centered at the y junction.. Standard exposure ranges from 70 to 80 kVp, 6 to 12 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Scapular body forming the lower arm of the Y.
- Scapular spine forming the transverse arm of the Y.
- Acromion process at the superior junction.
- Coracoid process visible.
- Humeral head at the Y intersection.
- Proximal humerus in profile.
Patient preparation
- Verify patient identity using two identifiers.
- Remove watches, bracelets, and radiopaque items from shoulder.
- Position patient erect in lateral position.
- Abduct the arm 90 degrees (parallel to floor).
- Keep scapula and humerus aligned in the scapular plane.
Position & centering point
The intersection of the scapular body, spine, and acromion (the Y junction), with arm abducted.
Central ray
Perpendicular to the scapular Y formed by the scapular body, spine, and acromion.
Exposure / technique
- kVp
- 70–80
- mAs
- 6–12
- SID
- 40" (102 cm)
- Notes
- Erect technique. Arm must be abducted 90 degrees; breathing is suspended inspiration.
Image-quality criteria
- Scapular Y clearly formed by scapular body, spine, and acromion.
- Humeral head centered at the Y junction.
- Acromion process visible at the superior arm of the Y.
- Coracoid process visible at the inferior arm of the Y.
- Scapular body and spine superimposed.
- Collimation: 3 inches on all sides of the shoulder.
Common errors / ARRT traps
- 1 Arm not abducted 90 degrees skews the Y formation.
- 2 Insufficient scapular Y formation from rotation or arm position.
- 3 Patient breathing motion blurs the image during exposure.
- 4 Off-centered CR misses the Y junction.
- 5 Body position too lateral or oblique distorts the Y symmetry.
Clinical indications
- Anterior or posterior humeral head dislocation evaluation.
- Shoulder trauma follow-up with suspected dislocation.
- Proximal humeral fracture assessment.
- Post-reduction shoulder dislocation check.
Aligned to the 2025 ARRT Content Specifications.