Oblique lateral mandible X-ray positioning (lying)
An extra face & sinuses view, used when a routine one is not enough. The patient lies on their side, the beam passes from side to side, tilted 15° towards the head, and the centring point is the angle of the mandible.
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
X-ray positioning/Face & sinuses
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. Lay the patient on the side to be examined, head tilted 15°.
Centring & collimation
Central ray
lateralCentre: the angle of the mandible.
Beam: lateral, angled 15° cephalad.
Collimate: the mandible of the side examined
Distance, receptor & grid
| Setting | Value | Notes |
|---|---|---|
| SID | 100 cm | |
| Receptor | 18 × 24 cm | landscape |
| Placement | Table bucky | Grid in |
| Angulation | 15° | cephalad |
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 | 1.6 | 0.63 |
| S | 70 | 2.5 | 1 |
| M | 70 | 3.2 | 1.25 |
| L | 70 | 5 | 2 |
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
- Near half of the mandible clear of the far half.
- 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 |
|---|---|---|
| Overlap | Insufficient tilt | Tilt 15° and angle the tube. |
Common questions
- Where do you centre for a mandible oblique lateral (lying) X-ray?
- The centring point is the angle of the mandible.
- What distance and beam angle does a mandible oblique lateral (lying) need?
- 100 cm from the tube to the receptor. The beam passes from side to side, tilted 15° towards the head.
- What size receptor, and do you need a grid?
- Use an 18 × 24 cm receptor, landscape, 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 mandible oblique lateral (lying)?
- Overlap. Usual cause: insufficient tilt. The fix: tilt 15° and angle the tube.
Try it in ScanFlo: the ScanFlo XR X-ray Room, coming soon, lets you set up a mandible oblique lateral (lying) in a 3D room and score your positioning. See ScanFlo XR →
Written by the ScanFlo team from everyday radiographic practice.