PA chest X-ray positioning (erect)
One of the routine chest views. The patient stands, the beam passes back to front (PA), straight on to the receptor, and the centring point is T7, in the midline.
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
Erect. Stand the patient facing the bucky, chin raised on its top edge, backs of the hands on the hips and the elbows and shoulders rolled forward so the scapulae swing clear of the lungs.
Centring & collimation
Central ray
PACentre: T7, in the midline (level with the inferior angles of the scapulae).
Beam: PA, perpendicular to the receptor.
Collimate: include both apices, both costophrenic angles and the lateral skin margins
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: R marker, upper outer corner
- 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 | 1 | 1 |
| S | 120 | 1.6 | 1.6 |
| M | 120 | 2 | 2 |
| L | 120 | 3.2 | 3.2 |
| Child | 90 | 2 | 2 |
These start from a classic film-screen chart (120 kV, 2 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
- Both lung apices and both costophrenic angles are included.
- Medial ends of the clavicles are equidistant from the spinous processes (no rotation).
- About ten posterior ribs are seen above the diaphragm (adequate inspiration).
- Scapulae are projected clear of the lung fields.
- Vertebrae and lung markings are just visible through the heart shadow.
- 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 |
|---|---|---|
| Clavicles asymmetric about the spine | Patient rotated | Bring both shoulders evenly against the bucky. |
| Scapulae overlie the lungs | Shoulders not rolled forward | Elbows forward, backs of hands on hips. |
| Fewer than nine ribs above the diaphragm | Exposure on poor inspiration | Coach the breath and expose at full inspiration. |
Common questions
- Where do you centre for a chest PA erect X-ray?
- The centring point is T7, in the midline (level with the inferior angles of the scapulae).
- What distance and beam angle does a chest PA erect need?
- 180 cm from the tube to the receptor. The beam passes back to front (PA), 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 PA erect?
- Clavicles asymmetric about the spine. Usual cause: patient rotated. The fix: bring both shoulders evenly against the bucky.
Try it in ScanFlo: the ScanFlo XR X-ray Room, coming soon, lets you set up a chest pa erect in a 3D room and score your positioning. See ScanFlo XR →
Written by the ScanFlo team from everyday radiographic practice.