Clavicle X-Ray Positioning: AP, AP Axial, and Trauma Views
The clavicle (collarbone) is one of the most frequently fractured bones in the human body, making clavicle X-ray positioning a critical skill for every radiologic technologist. Whether you're working in an emergency department or a general imaging center, knowing how to get a diagnostic clavicle series on the first try saves time, reduces patient discomfort, and minimizes repeat exposures.
In this guide, you'll learn the standard two-view clavicle series — AP and AP axial (cephalic) — with Clark's-verified centering points, technique factors, image evaluation criteria, and high-yield ARRT exam tips.
For other shoulder girdle positioning guides, check out our shoulder X-ray positioning guide and rib X-ray positioning guide.
Clavicle Anatomy: What You Need to Know
Before you position a patient, let's review the key anatomy. The clavicle is an S-shaped long bone that connects the sternum (via the sternoclavicular joint medially) to the scapula (via the acromioclavicular joint laterally).
Key landmarks for positioning:
- Sternoclavicular (SC) joint — the medial articulation, your landmark for collimation
- Acromioclavicular (AC) joint — the lateral articulation, visible at the distal end
- Mid-clavicle — your centering point for the AP view
- Coracoid process — inferior to the clavicle on the scapula, useful for orientation
The clavicle sits directly over the first and second ribs and the upper scapula, which is why the AP axial view with cephalic angulation is so valuable — it projects the clavicle above these overlapping structures.
The Standard Clavicle Series
A complete clavicle series consists of two views:
- AP clavicle — perpendicular CR, shows the clavicle in anatomical position
- AP axial (cephalic) clavicle — CR angled 15–30° cephalad, "flattens out" the clavicle above the shoulder girdle
Some departments include an AP erect view of both clavicles for comparison in trauma cases, but the two-view ipsilateral series is the standard minimum.
💡 ARRT Exam Tip
The clavicle series requires a minimum of two views (AP + AP axial). A single AP view is not sufficient for a complete clavicle series. The AP axial view is essential for evaluating fracture angulation and displacement. This is frequently tested on the registry.
AP Clavicle View
The AP clavicle view is the starting point of the series and demonstrates the clavicle in its natural anatomical relationship with the scapula and proximal humerus.
Patient Positioning
- Position: Erect (preferred) or supine if the patient cannot stand
- Body position: Posterior aspect of the shoulder against the image receptor — the midcoronal plane is parallel to the IR
- Affected arm: In neutral position by the patient's side (do not rotate if trauma is suspected)
- Head: Turned slightly away from the affected side to reduce superimposition
- IR orientation: Landscape (18 × 24 cm or 10 × 12 inches)
Technical Factors
| Parameter | AP Clavicle |
|---|---|
| IR size | 18 × 24 cm (10 × 12 in), landscape |
| SID | 100 cm (40 in) |
| CR | Perpendicular, centered at mid-clavicle |
| kVp | 60–70 |
| mAs | 10–18 |
| Grid | Yes |
| Breathing | Suspended expiration |
| Collimation | Superior to skin margins, inferior to mid-scapula, lateral to skin margin, medial to include SC joint |
Centering Point (Clark's)
Palpate the clavicle from the SC joint to the AC joint. Center the CR perpendicular to the midpoint of the clavicle. According to Clark's Pocket Handbook for Radiographers, the centering point is the mid-clavicle with the CR perpendicular, providing a true AP projection of the entire bone. The S-shaped curve of the clavicle means the midpoint is usually at the apex of the medial curve.
Evaluation Criteria
- The entire clavicle is visualized from the SC joint medially to the AC joint laterally
- The glenoid cavity and scapula are demonstrated in AP orientation
- There is a slight overlap of the humeral head with the glenoid
- No rotation — the clavicle should not appear foreshortened or overlapped
- Sharp bony trabecular detail with appropriate penetration at the SC joint
🚨 Clinical Pearl
A common error on the AP clavicle is over-rotation of the patient's body. If the patient is rotated toward or away from the affected side, the clavicle will appear foreshortened and the SC joint will be obscured. Keep the midcoronal plane parallel to the image receptor. For trauma patients, this is especially challenging because pain causes them to rotate toward the injured side.
AP Axial (Cephalic) Clavicle View
The AP axial view is performed after the AP and is often the view that reveals subtle fractures not visible on the straight AP projection.
Patient Positioning
- Position: Identical to the AP view
- Body position: Same — posterior shoulder against the IR
- Affected arm: Neutral by the side
Technical Factors
| Parameter | AP Axial Clavicle |
|---|---|
| IR size | Same as AP |
| SID | Same |
| CR | 15–30° cephalad, centered just below mid-clavicle |
| kVp | Same (60–70) |
| mAs | Same (10–18) |
| Grid | Yes |
⚠️ Important — Compensate for the Angle
When angling the CR cephalad, you must shift the IR upward to compensate. If you don't, the clavicle will project off the top of the image receptor. The cephalad angle also elongates the clavicle slightly, giving you a different perspective on fracture alignment. This is a common oversight among student technologists.
Why the Cephalic Angle Works
The 15–30° cephalad angulation projects the clavicle above the scapula and the second and third ribs. This "unfolds" the clavicle, making it easier to see:
- The full length of the bone without superimposition
- Fracture angulation and displacement in the AP plane
- Medial clavicle detail that may be obscured by overlying ribs on the straight AP
Evaluation Criteria
- The clavicle is "flattened out," projecting above the shoulder girdle
- The SC and AC joints are visualized
- The humeral head shows slight overlap with the glenoid
- There is no superimposition of the mid-clavicle over the ribs
💡 ARRT Exam Tip
If you can't see a fracture on the AP projection, the AP axial view should be your next step. This is frequently tested — the AP axial is better for demonstrating subtle nondisplaced fractures and determining the degree of fragment angulation. Think of the AP axial as your "second look" when clinical suspicion is high but the AP looks normal.
Technique Comparison: AP vs AP Axial
| Feature | AP Clavicle | AP Axial Clavicle |
|---|---|---|
| CR angle | Perpendicular (0°) | 15–30° cephalad |
| Centering | Mid-clavicle | Just below mid-clavicle |
| IR adjustment | Standard position | Shift IR superiorly |
| Best for | Baseline anatomy, AC joint | Subtle fractures, displacement |
| Clavicle appearance | Anatomical position | "Flattened" above ribs |
Trauma Considerations
Clavicle fractures are common injuries, especially from:
- FOOSH (Fall On Outstretched Hand)
- Direct blow to the shoulder (sports injuries, motor vehicle collisions)
- Birth trauma (neonatal clavicle fracture — the most common obstetric fracture)
Positioning the Trauma Patient
When you suspect a clavicle fracture:
- Do not move the affected arm — keep it in neutral position by the patient's side
- Do not force the patient to stand — supine AP and cross-table AP axial are acceptable alternatives
- Use erect positioning if possible — gravity helps separate fracture fragments for better visualization
- Explain every step — clavicle fractures are painful, and patient cooperation improves image quality
- Support the affected side — placing a small radiolucent pad under the elbow can reduce motion artifact
Pediatric Notes
- Clavicle fractures in children are often greenstick fractures — the cortex buckles without complete disruption
- Nonaccidental trauma (NAT) should be considered in infants with clavicle fractures without a clear mechanism
- Lower kVp (55–60) and smaller IR are used for pediatric patients; no grid if the body part is less than 10 cm thick
- The AP and AP axial series is the same for pediatric patients, with dose optimization per ALARA principles
🚨 Clinical Pearl — Neonatal Clavicle Fracture
The clavicle is the most commonly fractured bone during childbirth (especially in shoulder dystocia). These fractures are managed conservatively and typically heal within 2–3 weeks without intervention. On the AP chest radiograph of a newborn, look for healing callus formation around the mid-clavicle — this is often an incidental finding on a follow-up study. This is also a high-yield topic on the ARRT regarding pediatric trauma.
Common Positioning Errors
| Error | Cause | Fix |
|---|---|---|
| Clavicle appears foreshortened | Patient rotated | Keep midcoronal plane parallel to IR |
| Clavicle projects off IR top | IR not shifted for cephalad angle | Shift IR superiorly when using cephalad angle |
| SC joint not visible | Collimation too tight medially | Widen medial collimation to include SC joint |
| AC joint clipped laterally | Collimation too tight laterally | Include lateral skin margin |
| Patient motion | Pain from trauma | Short exposure time, support arm, explain procedure |
| Overexposed lateral clavicle | Technique too high for thin lateral aspect | Consider two separate techniques if using DR |
The Companion Shadow of the Clavicle
One unique radiographic finding you'll see on clavicle radiographs is the companion shadow — a linear lucency parallel to the superior border of the clavicle.
What it is: A skin fold artifact or Mach band effect created by the difference in tissue thickness at the skin surface overlying the clavicle. The margin between the air and the skin acts as a lucent line, creating the illusion of a second, parallel bone margin.
Why it matters on the ARRT exam:
- The companion shadow can mimic a pneumothorax on chest and clavicle radiographs
- It appears as a parallel line above the clavicle, not within the lung field
- True pneumothorax lines are lateral to the lung with absent lung markings beyond
- The companion shadow is visible above the clavicle and does not track along the chest wall
💡 ARRT Exam Tip — Companion Shadow
This is a classic registry question. The companion shadow is a normal variant / skin fold artifact. On the ARRT, you'll need to distinguish it from a true pneumothorax — a pneumothorax line shows absent lung markings peripherally, whereas the companion shadow runs parallel to the superior clavicle and does not extend into the lung field. Think of it as a "shadow" of the clavicle created by the skin surface.
Clavicle Positioning at a Glance
| View | CR Direction | Centering | Key Tip |
|---|---|---|---|
| AP | Perpendicular | Mid-clavicle | Keep patient from rotating |
| AP Axial | 15–30° cephalad | Just below mid-clavicle | Shift IR up to compensate |
ARRT Content Specifications: What's Changing in 2027
The ARRT periodically updates its content specifications, and the clavicle is affected by a notable reclassification in 2027:
📝 Content Spec Change
Clavicle is moving from the Upper Extremity section to the Thorax section in the updated ARRT Radiography Content Specifications. This means exam questions about clavicle positioning may appear under a different content category. The positioning itself hasn't changed — just how the ARRT categorizes it. When you're studying, make sure your review materials reflect this update. For more on ARRT exam preparation, see our ARRT exam prep guide.
Summary
| Projection | Patient Position | CR | Centering Point | Purpose |
|---|---|---|---|---|
| AP Clavicle | Erect/supine, arm neutral, midcoronal plane parallel to IR | 0° (perpendicular) | Mid-clavicle | Survey anatomy, AC joint |
| AP Axial Clavicle | Same as AP | 15–30° cephalad | Just below mid-clavicle | Subtle fractures, displacement |
📝 Key Takeaway
The AP axial clavicle with 15–30° cephalad angulation is the most important view for identifying subtle clavicle fractures. Master the cephalad angle and IR shift, and you'll consistently produce diagnostic clavicle series. On the ARRT, expect questions on the clavicle series composition (two views minimum), the centering points for both projections, the companion shadow as a normal variant, and the 2027 reclassification of the clavicle to the thorax section. For more upper extremity and shoulder girdle practice, see our shoulder X-ray positioning guide and the rib X-ray positioning article.