Lateral chest X-ray positioning (erect)
One of the routine chest views. 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. Patient stands left side to the bucky with both arms lifted to grip the overhead bar; keep the mid-coronal plane at right angles to the detector.
Centring & collimation
Central ray
lateralCentre: the mid-axillary line at T7.
Beam: lateral, perpendicular to the receptor.
Collimate: apices to the posterior costophrenic angles, sternum to the spine
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 | 2 |
| S | 120 | 3.2 | 3.2 |
| M | 120 | 4 | 4 |
| L | 120 | 6.3 | 6.3 |
| Child | 90 | 2.5 | 2.5 |
These start from a classic film-screen chart (120 kV, 4 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
- Apices and both posterior costophrenic angles are included.
- The sternum is seen in true profile.
- Posterior rib margins are nearly superimposed.
- The arms do not overlie the upper thorax.
- 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 |
|---|---|---|
| Posterior ribs separated widely | Trunk rotated | Keep the mid-coronal plane perpendicular; check the shoulders. |
| Arm soft tissue over the apices | Arms not raised enough | Raise the arms and grip the support above the head. |
Common questions
- Where do you centre for a chest lateral erect X-ray?
- The centring point is the mid-axillary line at T7.
- What distance and beam angle does a chest lateral erect 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 erect?
- Posterior ribs separated widely. Usual cause: trunk rotated. The fix: keep the mid-coronal plane perpendicular; check the shoulders.
Try it in ScanFlo: the ScanFlo XR X-ray Room, coming soon, lets you set up a chest lateral erect in a 3D room and score your positioning. See ScanFlo XR →
Written by the ScanFlo team from everyday radiographic practice.