Lateral thoracic spine X-ray positioning
One of the routine T-spine views. The patient lies on their side, the beam passes from side to side, straight on to the receptor, and the centring point is T7, through the mid-axillary line.
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. Lay the patient on the left side with the knees flexed, arms forward, the spine horizontal (pad the waist).
Centring & collimation
Central ray
lateralCentre: T7, through the mid-axillary line.
Beam: lateral, perpendicular to the receptor.
Collimate: T3 to L1
Distance, receptor & grid
| Setting | Value | Notes |
|---|---|---|
| SID | 100 cm | |
| Receptor | 18 × 43 cm | portrait |
| 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: Quiet breathing.
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 | 20 | 8 |
| S | 70 | 32 | 12.5 |
| M | 70 | 40 | 16 |
| L | 70 | 63 | 25 |
These start from a classic film-screen chart (70 kV, 80 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
- Vertebral bodies seen through blurred ribs and lung.
- Posterior margins superimposed.
- 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 |
|---|---|---|
| Ribs sharp over the bodies | Breath held | Use quiet breathing with a longer exposure. |
Common questions
- Where do you centre for a thoracic spine lateral X-ray?
- The centring point is T7, through the mid-axillary line.
- What distance and beam angle does a thoracic spine lateral need?
- 100 cm from the tube to the receptor. The beam passes from side to side, straight on to the receptor.
- What size receptor, and do you need a grid?
- Use an 18 × 43 cm receptor, portrait, in the table bucky. A grid is needed.
- What should the patient do with their breathing?
- They can keep breathing gently; no breath-hold is needed.
- What goes wrong most often on a thoracic spine lateral?
- Ribs sharp over the bodies. Usual cause: breath held. The fix: use quiet breathing with a longer exposure.
Try it in ScanFlo: the ScanFlo XR X-ray Room, coming soon, lets you set up a thoracic spine lateral in a 3D room and score your positioning. See ScanFlo XR →
Written by the ScanFlo team from everyday radiographic practice.