Elbow AP is a radiography positioning projection of the Upper Extremity. Seated, arm extended on IR, palm supinated. SID 40". The centering point is located mid-elbow joint, about 3/4 inch (2 cm) distal to the midpoint of a line between the epicondyles. The central ray is perpendicular to the IR, directed to the mid-elbow joint. Image-quality criteria include elbow joint space open with the arm fully extended and the CR centered, distal humerus, proximal radius, and proximal ulna all included. A sample technique is 70 kVp with DR 1.4 or CR 2.5 mAs, at an SID of 40 inches (102 cm).
Watch the setup
All steps (4)
- Seat the patient at the end of the table with the elbow fully extended, if possible.
- Extend the elbow, supinate the hand, and align the arm and forearm with the long axis of the IR.
- Center the elbow joint to the center of the IR.
- Ask the patient to lean laterally as needed, so the interepicondylar plane is parallel to the IR.
3D anatomy: BodyParts3D, © The Database Center for Life Science. Posed, rendered and labelled by RadTechPrepper. These animations are licensed CC BY-SA 4.0. Credits
Anatomy demonstrated
- Distal humerus.
- Proximal radius and ulna.
- Medial and lateral epicondyles.
- Olecranon process seated in the olecranon fossa.
- Radial head, neck, and tuberosity.
Patient preparation
- WARNING: with possible spinal injury or severe trauma, do not attempt to move the patient; do not rotate a severely injured part or remove splints (Bontrager). Merrill's: do not attempt true AP or lateral positioning of a severely injured limb; take two projections 90 degrees apart, moving it as little as possible, and move the IR and tube if the patient cannot reach the position.
- Verify patient identity using two identifiers.
- Remove watches, bracelets, and any radiopaque items from the arm.
- Seat the patient at the end of the table with the elbow fully extended, if possible.
- Extend the elbow, supinate the hand, and align the arm and forearm with the long axis of the IR.
- Center the elbow joint to the center of the IR.
- Ask the patient to lean laterally as needed, so the interepicondylar plane is parallel to the IR.
Position & centering point
Mid-elbow joint, about 3/4 inch (2 cm) distal to the midpoint of a line between the epicondyles.
Central ray
Perpendicular to the IR, directed to the mid-elbow joint.
Exposure / technique
- kVp
- 70
- mAs
- DR 1.4 / CR 2.5
- SID
- 40" (102 cm)
- Notes
- Tabletop technique, nongrid. Collimate on four sides to the area of interest. Sample technique: DR 1.4 / CR 2.5 mAs at 70 kVp, 40 in SID, for an 8 cm part. Adjust for your equipment.
kVp and mAs are sample values. Use caution when applying them in your department.
Image-quality criteria
- Elbow joint space open with the arm fully extended and the CR centered.
- Distal humerus, proximal radius, and proximal ulna all included.
- Radial head, neck, and tuberosity show only slight overlap of the proximal ulna.
- Medial and lateral epicondyles are symmetric.
- Bone trabeculae and soft tissue sharp, no motion blur.
- Collimation: 3 inches proximal and distal to the elbow joint.
Common errors
- 1 Hand pronated: the radius crosses over the ulna at the proximal forearm.
- 2 Interepicondylar plane not parallel to the IR (patient not leaning laterally), so the elbow is rotated.
- 3 Elbow not fully extended, so the joint space is not open.
- 4 Off-centered CR clips the proximal radius or distal humerus.
- 5 Hand not supinated, so the bones of the forearm rotate.
- 6 Shoulder, humerus and elbow not in the same plane.
- 7 Pronated hand spins the radius over the ulna at the proximal joint.
- 8 CR not at the mid-elbow joint.
Clinical indications
- Trauma evaluation for elbow fracture or dislocation.
- Pathologic processes such as osteomyelitis and arthritis.