AP humerus X-ray positioning (trauma)
An extra humerus view, used when a routine one is not enough. The patient sits, the beam passes front to back (AP), straight on to the receptor, and the centring point is the mid-shaft.
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
Sitting. Seat the patient against the bucky with the forearm across the body in its sling.
Centring & collimation
Central ray
APCentre: the mid-shaft.
Beam: AP, perpendicular to the receptor.
Collimate: shoulder to elbow
Distance, receptor & grid
| Setting | Value | Notes |
|---|---|---|
| SID | 110 cm | |
| Receptor | 18 × 43 cm | portrait |
| Placement | Erect (wall) 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 | 2 | 0.8 |
| S | 70 | 3.2 | 1.25 |
| M | 70 | 4 | 1.6 |
| L | 70 | 6.3 | 2.5 |
These start from a classic film-screen chart (70 kV, 6.3 mAs at 140 cm) and are adjusted for a digital detector at 110 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
- Both joints included without moving the arm.
- 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 |
|---|---|---|
| Elbow cut off | Field too short | Open the field to include the elbow. |
Common questions
- Where do you centre for a humerus AP (after injury) X-ray?
- The centring point is the mid-shaft.
- What distance and beam angle does a humerus AP (after injury) need?
- 110 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 × 43 cm receptor, portrait, in the wall 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 a humerus AP (after injury)?
- Elbow cut off. Usual cause: field too short. The fix: open the field to include the elbow.
Try it in ScanFlo: the ScanFlo XR X-ray Room, coming soon, lets you set up a humerus ap (after injury) in a 3D room and score your positioning. See ScanFlo XR →
Written by the ScanFlo team from everyday radiographic practice.