Elbow Axiolateral, Coyle (Radial Head) is a radiography positioning projection of the Upper Extremity. Elbow flexed 90 degrees, palm flat on IR. CR angled 45 degrees toward shoulder. The centering point is located radial head, at the mid-elbow joint. Elbow flexed 90 degrees, palm flat on IR. The central ray is CR angled 45 degrees toward the shoulder, entering at the radial head. Image-quality criteria include radial head, neck, and tuberosity in profile, free of superimposition except for a small part of the coronoid process, open humeroradial joint space. The SID is 40 inches (102 cm).
Anatomy demonstrated
- Radial head free of superimposition except for a small part of the coronoid process.
- Radial neck and tuberosity.
- Capitulum of the humerus.
- Open humeroradial joint.
- Distal humerus, distorted by the 45-degree angle.
- Proximal radius and ulna.
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 radiopaque items from the arm.
- Seat the patient at the end of the table, or for trauma position supine on the table or cart.
- Flex the elbow 90 degrees with the palm flat against the IR.
- Adjust so humerus, elbow, and wrist sit in the same plane.
Position & centering point
Radial head, at the mid-elbow joint. Elbow flexed 90 degrees, palm flat on IR.
Central ray
CR angled 45 degrees toward the shoulder, entering at the radial head.
Exposure / technique
- kVp
- N/A
- mAs
- N/A
- SID
- 40" (102 cm)
- Notes
- Useful when the patient cannot fully extend the elbow for the medial or lateral oblique projections. In trauma, supine on the table or cart with a horizontal CR (Merrill's) directed cephalad 45 degrees. Bontrager digital range: 65 to 75 kV, adding 4 to 6 kV from the lateral elbow because of the angled CR. Neither Bontrager nor Merrill's prints mAs for this projection.
Image-quality criteria
- Radial head, neck, and tuberosity in profile, free of superimposition except for a small part of the coronoid process.
- Open humeroradial joint space.
- Humeral epicondyles distorted by the CR angle.
- Distal humerus and proximal forearm both included.
- Bone trabeculae sharp, no motion blur.
- Collimation: 3 inches proximal and distal to the joint.
Common errors
- 1 CR not angled 45 degrees toward the shoulder.
- 2 Humerus, elbow and wrist not on the same plane.
- 3 Hand not pronated.
- 4 CR not centered to the radial head at the mid-elbow joint.
Clinical indications
- Suspected radial head or neck fracture.
- Patient unable to fully extend the elbow for the medial or lateral oblique projections.