Lateral mastoid X-ray positioning (Schüller)
An extra skull view, used when a routine one is not enough. The patient lies on their side, the beam passes from side to side, tilted 25° towards the feet, and the centring point is 5 cm above the uppermost external auditory meatus.
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
Lateral recumbent. Remove dentures, earrings, hair clips and anything in the hair. Head lateral with the side examined against the detector, auricle folded forward. Take both sides.
Centring & collimation
Central ray
lateralCentre: 5 cm above the uppermost external auditory meatus.
Beam: lateral, angled 25° caudad.
Collimate: the mastoid of the side nearest the detector
Distance, receptor & grid
| Setting | Value | Notes |
|---|---|---|
| SID | 100 cm | |
| Receptor | 18 × 24 cm | portrait |
| Placement | Table bucky | Grid in |
| Angulation | 25° | caudad |
Marker & breathing
- Marker: R or L marker on the side nearest the detector
- Breathing: No breathing instruction needed.
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 | 6.3 | 2.5 |
| S | 70 | 10 | 4 |
| M | 70 | 12.5 | 5 |
| L | 70 | 20 | 8 |
These start from a classic film-screen chart (70 kV, 25 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
- Mastoid air cells clear of the opposite side.
- Temporomandibular joint in front of the meatus.
- 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 |
|---|---|---|
| Pinna over the air cells | Ear not folded | Fold the auricle forward. |
Common questions
- Where do you centre for a mastoid lateral (Schüller) X-ray?
- The centring point is 5 cm above the uppermost external auditory meatus.
- What distance and beam angle does a mastoid lateral (Schüller) need?
- 100 cm from the tube to the receptor. The beam passes from side to side, tilted 25° towards the feet.
- What size receptor, and do you need a grid?
- Use an 18 × 24 cm receptor, portrait, in the table bucky. A grid is needed.
- Where does the lead marker go?
- R or L marker on the side nearest the detector.
- What goes wrong most often on a mastoid lateral (Schüller)?
- Pinna over the air cells. Usual cause: ear not folded. The fix: fold the auricle forward.
Try it in ScanFlo: the ScanFlo XR X-ray Room, coming soon, lets you set up a mastoid lateral (schüller) in a 3D room and score your positioning. See ScanFlo XR →
Written by the ScanFlo team from everyday radiographic practice.