Oblique lateral mandible X-ray positioning (sitting)
One of the routine face & sinuses views. The patient sits, the beam passes from side to side, tilted 15° towards the head, and the centring point is the angle of the mandible of the side examined.
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
Sitting. Remove dentures, earrings, hair clips and anything in the hair. Seat the patient with the side to be examined against the tilted holder, head tilted toward it 15°.
Centring & collimation
Central ray
lateralCentre: the angle of the mandible of the side examined.
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 | Erect (wall) 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
- The near half of the mandible is clear of the far half.
- Body and ramus shown.
- 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 |
|---|---|---|
| Two sides superimposed | No tube angle | Angle 15° and tilt the head. |
Common questions
- Where do you centre for a mandible oblique lateral X-ray?
- The centring point is the angle of the mandible of the side examined.
- What distance and beam angle does a mandible oblique lateral 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 wall 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?
- Two sides superimposed. Usual cause: no tube angle. The fix: angle 15° and tilt the head.
Try it in ScanFlo: the ScanFlo XR X-ray Room, coming soon, lets you set up a mandible oblique lateral in a 3D room and score your positioning. See ScanFlo XR →
Written by the ScanFlo team from everyday radiographic practice.