AP cervical spine X-ray positioning
One of the routine C-spine views. The patient sits, the beam passes front to back (AP), tilted 15° towards the head, and the centring point is the thyroid cartilage.
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
Sitting. Seat the patient with the back against the bucky, chin raised so the lower jaw and the occiput are level.
Centring & collimation
Central ray
APCentre: the thyroid cartilage.
Beam: AP, angled 15° cephalad.
Collimate: C3 to T2
Distance, receptor & grid
| Setting | Value | Notes |
|---|---|---|
| SID | 110 cm | |
| Receptor | 18 × 24 cm | portrait |
| Placement | Erect (wall) bucky | Grid in |
| Angulation | 15° | cephalad |
Marker & breathing
- Marker: R or L marker on the side nearest the detector
- Breathing: Suspend respiration.
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 | 4 | 2 |
| S | 70 | 6.3 | 3.2 |
| M | 70 | 8 | 4 |
| L | 70 | 12.5 | 6.3 |
These start from a classic film-screen chart (70 kV, 12.5 mAs at 140 cm) and are adjusted for a digital detector at 110 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
- C3 to T2 shown, the mandible over C1/C2.
- Spinous processes central, intervertebral spaces open.
- 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 |
|---|---|---|
| Mandible over C3 | Chin too low | Raise the chin to bring the jaw and occiput level. |
Common questions
- Where do you centre for a cervical spine AP X-ray?
- The centring point is the thyroid cartilage.
- What distance and beam angle does a cervical spine AP need?
- 110 cm from the tube to the receptor. The beam passes front to back (AP), tilted 15° towards the head.
- What size receptor, and do you need a grid?
- Use an 18 × 24 cm receptor, portrait, in the wall bucky. A grid is needed.
- What should the patient do with their breathing?
- Ask them to stop breathing for the moment of the exposure.
- What goes wrong most often on a cervical spine AP?
- Mandible over C3. Usual cause: chin too low. The fix: raise the chin to bring the jaw and occiput level.
Try it in ScanFlo: the ScanFlo XR X-ray Room, coming soon, lets you set up a cervical spine ap in a 3D room and score your positioning. See ScanFlo XR →
Written by the ScanFlo team from everyday radiographic practice.