AP acromioclavicular (AC) joint X-ray positioning
An extra shoulder view, used when a routine one is not enough. The patient lies on their back, the beam passes front to back (AP), straight on to the receptor, and the centring point is the acromioclavicular joint.
By the ScanFlo Editorial Team · Updated
In this section · X-ray positioning
- X-ray positioning guides
- Skull positioning
- Face & sinuses positioning
- Soft tissue neck positioning
- C-spine positioning
- Chest positioning
- Shoulder positioning
- Humerus positioning
- Elbow positioning
- Forearm positioning
- Wrist positioning
- Hand positioning
- T-spine positioning
- Abdomen positioning
- L-spine positioning
- Sacrum & SI joints positioning
- Pelvis positioning
- Hip positioning
- Femur positioning
- Knee positioning
- Tibia & fibula positioning
- Ankle positioning
- Foot positioning
Still being checked: a radiographer is reviewing this guide. If your department does it differently, follow your department.
Patient position
Supine. Supine with the upper arm bent away from the body.
Centring & collimation
Central ray
APCentre: the acromioclavicular joint.
Beam: AP, perpendicular to the receptor.
Collimate: the joint and lateral clavicle
Distance, receptor & grid
| Setting | Value | Notes |
|---|---|---|
| SID | 100 cm | |
| Receptor | 18 × 24 cm | landscape |
| Placement | Table bucky | Grid in |
| Angulation | None | Perpendicular to the receptor |
Marker & breathing
- Marker: R or L marker on the side nearest the detector
- Breathing: Suspend respiration.
Exposure by patient size
Treat these as a starting point. Your detector, your generator and the patient in front of you will all move the numbers.
| Patient size | kV | mAs (chart) | mAs (DR default) |
|---|---|---|---|
| XS | 70 | 1.6 | 0.63 |
| S | 70 | 2.5 | 1 |
| M | 70 | 3.2 | 1.25 |
| L | 70 | 5 | 2 |
| Child | 53 | 1.6 | 0.63 |
These start from a classic film-screen chart (70 kV, 6.3 mAs at 140 cm) and are adjusted for a digital detector at 100 cm. The DR column is what ScanFlo's console suggests; each step up or down changes the mAs by about a quarter.
Image quality checklist
- The joint is shown clear of the acromion.
- The anatomical side marker is visible, correct and clear of the anatomy.
- Collimation borders are visible on all sides, no wider than the area requested.
Faults & how to fix them
| Fault | Cause | Fix |
|---|---|---|
| Joint obscured | Overexposed | Reduce exposure for soft bone. |
Common questions
- Where do you centre for an acromioclavicular joint AP X-ray?
- The centring point is the acromioclavicular joint.
- What distance and beam angle does an acromioclavicular joint AP need?
- 100 cm from the tube to the receptor. The beam passes front to back (AP), straight on to the receptor.
- What size receptor, and do you need a grid?
- Use an 18 × 24 cm receptor, landscape, in the table bucky. A grid is needed.
- What should the patient do with their breathing?
- Ask them to stop breathing for the moment of the exposure.
- What goes wrong most often on an acromioclavicular joint AP?
- Joint obscured. Usual cause: overexposed. The fix: reduce exposure for soft bone.
Try it in ScanFlo: the ScanFlo XR X-ray Room, coming soon, lets you set up a acromioclavicular joint ap in a 3D room and score your positioning. See ScanFlo XR →
Written by the ScanFlo team from everyday radiographic practice.