Clavicle X-Ray Positioning: 2 Views (AP & AP Axial) with Centering Points & Trauma Tips
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 a commonly used two-view clavicle series — AP and AP axial (cephalic) — with centering guidance, protocol-dependent technical factors, image evaluation criteria, trauma considerations, and the official 2027 ARRT content-category update.
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
On an AP projection, portions of the clavicle are superimposed on the upper ribs and scapula. Cephalic angulation projects more of the clavicle above these structures and supplies a complementary view.
The Standard Clavicle Series
A commonly taught and used clavicle series consists of two views, although the examination order and departmental protocol always control:
- AP clavicle — perpendicular CR, shows the clavicle in anatomical position
- AP axial (cephalic) clavicle — cephalically angled CR, reducing superimposition by projecting more of the clavicle above the upper ribs and scapula
Additional or alternative projections may be requested for a specific injury or local protocol. Do not substitute bilateral AC-joint stress views for a routine unilateral clavicle examination unless specifically ordered.
💡 Protocol Note
AP plus AP axial is a common two-projection teaching and clinical protocol. For example, the Royal Children's Hospital Melbourne specifies AP plus AP with 15° cephalic tilt, while the Heritage Valley Health System School of Radiography manual specifies AP plus AP axial with 20–30° cephalic angulation. These examples are not a universal angle rule; follow the order and your department's protocol.
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: Resting by the side where tolerated; in trauma, avoid unnecessary movement and preserve immobilization unless clinically authorized
- Head: Raise the chin and, if tolerated, turn it slightly away so the mandible does not obscure the medial clavicle
- IR orientation: Crosswise; a 24 × 30 cm (10 × 12 in) receptor is a common adult teaching choice, but use a receptor and collimation sufficient to include both ends of the clavicle
Technical Factors
| Parameter | AP Clavicle |
|---|---|
| IR size | Common adult teaching choice: 24 × 30 cm (10 × 12 in), crosswise; adapt to patient/detector |
| SID | Use departmental protocol (100 cm/40 in is a common teaching value) |
| CR | Perpendicular, centered at mid-clavicle |
| Exposure | Use the current site-specific technique chart; do not apply a universal kVp/mAs value across systems and patient sizes |
| Grid | Protocol- and thickness-dependent; do not add a grid routinely when the local pediatric/adult chart does not call for one |
| Breathing | Suspend respiration for the exposure; use the phase specified locally |
| Collimation | Four-sided collimation to include the entire clavicle, SC and AC joints, and adjacent required soft tissue |
Centering Point
Palpate the clavicle from the SC joint to the AC joint and center the perpendicular CR to the mid-clavicle. Confirm that collimation includes both joints rather than relying on an assumed relationship between the midpoint and the visible curves of this S-shaped bone.
Evaluation Criteria
- The entire clavicle is visualized from the SC joint medially to the AC joint laterally
- Both the SC and AC joints are included (the joint spaces need not both be open)
- No avoidable rotation — positioning is symmetric enough for the requested AP projection
- 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 complements the AP by reducing overlap with the upper ribs and scapula and showing fracture alignment from a different projection.
Patient Positioning
- Position: Identical to the AP view
- Body position: Same — posterior shoulder against the IR
- Affected arm: Resting by the side where tolerated; avoid unnecessary trauma movement
Technical Factors
| Parameter | AP Axial Clavicle |
|---|---|
| IR size | Same as AP |
| SID | Same |
| CR | Cephalad per local protocol (published examples: 15° and 20–30°), directed to mid-clavicle |
| Exposure | Use the site-specific technique chart |
| Grid | Protocol- and thickness-dependent |
⚠️ Important — Compensate for the Angle
Cephalic angulation shifts the projected anatomy superiorly. Position the IR and collimate from the light field so the entire projected clavicle remains included; the amount of receptor adjustment depends on geometry rather than a fixed mandatory shift.
Why the Cephalic Angle Works
The protocol-selected cephalic angulation projects more of the clavicle above the upper ribs and scapula, reducing superimposition and helping demonstrate:
- The full length of the bone with less superimposition
- Fracture angulation and displacement from a complementary projection
- Medial clavicle detail that may be obscured by overlying ribs on the straight AP
Evaluation Criteria
- The entire clavicle, including the SC and AC joints, is included
- Most of the clavicle is projected above the upper ribs and scapula, as expected for the selected local angle and habitus
- There is no avoidable rotation or motion, and cortical/trabecular detail is diagnostic
💡 Clinical Reasoning
Do not call a suspected fracture excluded from one projection alone. Complete the ordered projections. If radiographs are negative or indeterminate but occult fracture remains suspected, the ACR rates CT without IV contrast or MRI without IV contrast as usually appropriate next imaging for adults; additional imaging is a clinician/radiologist decision.
Technique Comparison: AP vs AP Axial
| Feature | AP Clavicle | AP Axial Clavicle |
|---|---|---|
| CR angle | Perpendicular (0°) | Cephalad per protocol (examples: 15° or 20–30°) |
| Centering | Mid-clavicle | Mid-clavicle |
| IR placement | Include entire clavicle | Account for superior projection and include entire clavicle |
| Role | Baseline projection | Complementary projection with less rib/scapular overlap |
| Clavicle appearance | More upper-rib/scapular overlap | More of clavicle projected above upper ribs/scapula |
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:
- Avoid unnecessary movement — support the affected arm and retain immobilization unless removal is clinically authorized
- Do not force the patient to stand — adapt AP and AP axial positioning supine when required by the patient's condition and local trauma protocol
- Use erect positioning only when safe and tolerated — positioning must not override spinal, trauma, or fall precautions
- Explain every step — clavicle fractures are painful, and patient cooperation improves image quality
- Support the affected side with approved radiolucent supports as needed, without changing fracture alignment
Pediatric Notes
- A greenstick fracture is an incomplete fracture in which one cortex fails while the opposite side bends; a simple cortical buckle describes a torus fracture, not the definition of greenstick
- An unexplained injury in an infant warrants age- and history-appropriate safeguarding assessment, but a clavicle fracture alone is not diagnostic of nonaccidental trauma
- Use pediatric-specific collimation and the approved technique chart; receptor size, kVp/mAs, and grid use must be selected for patient size and the imaging system rather than by a universal cutoff
- AP plus cephalically tilted AP is one published pediatric protocol, but perform only the ordered/local projections and optimize dose
🚨 Clinical Pearl — Neonatal Clavicle Fracture
Clavicle fracture is the most common perinatal fracture associated with birth trauma. Most neonatal clavicular fractures are treated conservatively and heal rapidly; callus may make an initially unrecognized fracture apparent later. Imaging findings and arm movement should be interpreted clinically, including assessment for associated brachial-plexus injury where indicated.
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 |
| Inadequate exposure or excessive detector exposure | Technique not matched to patient/system | Use the approved technique chart and review the exposure indicator; do not repeat a diagnostic image solely for appearance |
The Companion Shadow of the Clavicle
A companion shadow is a smooth, homogeneous soft-tissue density with a defined margin that runs parallel to part of a bony landmark such as the clavicle. It is not visible on every radiograph.
What it is: Soft tissue overlying the clavicle seen in profile. It is a density rather than a lucent fracture line. A separate chest-radiography pitfall is a skin fold that can mimic a pleural line through edge enhancement; that phenomenon should not be used as the definition of a clavicular companion shadow.
Why recognition matters:
- It follows part of the clavicular contour and may be mistaken for local pathology if its soft-tissue origin is not recognized
- A fracture is a lucent cortical disruption and must be assessed in both ordered projections
- Do not infer or exclude pneumothorax from this clavicular sign; assess the pleural line and peripheral lung markings on an appropriate chest study
💡 Companion Shadow Check
Describe it accurately: a smooth soft-tissue density parallel to a bony landmark. Do not call it a linear lucency, a skin fold, a Mach band, or a pneumothorax mimic. Correlate any suspected abnormal line across projections and escalate unexpected findings for radiologist review.
Clavicle Positioning at a Glance
| View | CR Direction | Centering | Key Tip |
|---|---|---|---|
| AP | Perpendicular | Mid-clavicle | Keep patient from rotating |
| AP Axial | Cephalad per local protocol | Mid-clavicle | Include the superiorly projected clavicle |
ARRT Content Specifications: What's Changing in 2027
The ARRT periodically updates its content specifications, and the clavicle is affected by a reclassification effective March 1, 2027:
📝 Content Spec Change
Clavicle moves from Extremity Procedures to Thorax and Abdomen Procedures (Thorax) in the ARRT Radiography Examination Content Specifications effective March 1, 2027. The documents identify content categories, not how many clavicle questions an individual exam will contain. The classification change does not itself prescribe a positioning technique. 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 general position as AP, adapted for condition | Cephalad per local protocol | Mid-clavicle | Complementary projection with reduced overlap |
📝 Key Takeaway
AP and AP axial are complementary projections in common clavicle protocols. Center both to the mid-clavicle, include the SC and AC joints, choose the cephalic angle specified locally, and account for superior projection on the receptor. A companion shadow is an overlying soft-tissue density—not a lucent skin-fold artifact. The official ARRT change documented here is the clavicle's move to the Thorax category effective March 1, 2027; ARRT does not publish a guaranteed clavicle question count. For more positioning practice, see our shoulder X-ray positioning guide and the rib X-ray positioning article.
Authoritative References
- Heritage Valley Health System School of Radiography: Routine Radiographic Procedure Manual — local US teaching protocol; page 3 lists AP and AP axial clavicle views, 10 × 12 in receptors, erect if possible, and 20–30° cephalad for the axial projection.
- Royal Children's Hospital Melbourne: Clavicle Fractures—Emergency Department — pediatric clinical guideline specifying AP plus AP with 15° cephalic tilt and describing common mechanisms and perinatal fractures.
- ACR Appropriateness Criteria: Acute Shoulder Pain — radiography is usually appropriate initial imaging; CT without contrast or MRI without contrast is usually appropriate when occult fracture is suspected after negative/indeterminate radiographs.
- ARRT Radiography Examination Content Specifications, effective March 1, 2027 — lists clavicle under Thorax and Abdomen Procedures → Thorax.
- Wikimedia Commons source record for the companion-shadow radiograph — image identity, authorship, and CC BY-SA 3.0 licensing.
