Lateral chest X-ray positioning (sitting)
An extra chest view, used when a routine one is not enough. The patient stands side-on, the beam passes from side to side, straight on to the receptor, and the centring point is the mid-axillary line at T7.
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, erect. Seat the patient side-on on a stool, left side to the bucky, tipped a little forward with both arms resting up on the bar.
Centring & collimation
Central ray
lateralCentre: the mid-axillary line at T7.
Beam: lateral, perpendicular to the receptor.
Collimate: apices to the posterior costophrenic angles
Distance, receptor & grid
| Setting | Value | Notes |
|---|---|---|
| SID | 180 cm | |
| Receptor | 35 × 43 cm | portrait |
| Placement | Erect (wall) bucky | Grid in |
| Angulation | None | Perpendicular to the receptor |
Marker & breathing
- Marker: L marker anterior to the sternum
- Breathing: Breathe in and hold.
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 | 120 | 2.5 | 2.5 |
| S | 120 | 4 | 4 |
| M | 120 | 5 | 5 |
| L | 120 | 8 | 8 |
| Child | 90 | 2.5 | 2.5 |
These start from a classic film-screen chart (120 kV, 5 mAs at 140 cm) and are adjusted for a digital detector at 180 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
- Sternum in profile and posterior ribs superimposed.
- Apices and posterior costophrenic angles included.
- 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 |
|---|---|---|
| Patient leaning back | No support in front | Lean the patient slightly forward onto the support. |
Common questions
- Where do you centre for a chest lateral sitting X-ray?
- The centring point is the mid-axillary line at T7.
- What distance and beam angle does a chest lateral sitting need?
- 180 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 a 35 × 43 cm receptor, portrait, in the wall bucky. A grid is needed.
- What should the patient do with their breathing?
- Ask them to breathe in and hold it while you expose.
- What goes wrong most often on a chest lateral sitting?
- Patient leaning back. Usual cause: no support in front. The fix: lean the patient slightly forward onto the support.
Try it in ScanFlo: the ScanFlo XR X-ray Room, coming soon, lets you set up a chest lateral sitting in a 3D room and score your positioning. See ScanFlo XR →
Written by the ScanFlo team from everyday radiographic practice.