AP Axial Cervical is a radiography positioning projection of the Spine. Supine or erect, CR 15-20° cephalad through C4. Lower cervical survey. The centering point is located enters at the level of the lower margin of the thyroid cartilage; the angled CR passes through C4. Centre the IR to the CR. The central ray is 20° cephalad erect (15° supine or with less lordosis; a kyphotic patient needs more than 20°), entering at the level of the lower margin of the thyroid cartilage to pass through C4. Image-quality criteria include C3 to T2 vertebral bodies and disc spaces clearly seen, intervertebral disc spaces open and symmetrical. A sample technique is 85 kVp with DR 3.2 or CR 6.3 mAs, at an SID of 40 inches (102 cm).
Watch the setup
All steps (4)
- Supine or erect, arms by the sides.
- Align the midsagittal plane to the CR and the midline of the IR.
- Adjust the head so a line from the lower margin of the upper incisors to the base of the skull (mastoid tips) is perpendicular to the IR; the line from the tip of the mandible to the base of the skull is then parallel to the angled CR.
- Ensure no rotation of the head or thorax.
3D anatomy: BodyParts3D, © The Database Center for Life Science. Posed, rendered and labelled by RadTechPrepper. These animations are licensed CC BY-SA 4.0. Credits
Anatomy demonstrated
- C3-C7 vertebral bodies.
- Intervertebral disc spaces C3-C7.
- Spinous processes of lower cervical vertebrae.
- Space between the pedicles.
Patient preparation
- Verify patient identity using two identifiers.
- Remove neck jewelry, dentures, and radiopaque objects.
- Supine or erect, arms by the sides.
- Align the midsagittal plane to the CR and the midline of the IR.
- Adjust the head so a line from the lower margin of the upper incisors to the base of the skull (mastoid tips) is perpendicular to the IR; the line from the tip of the mandible to the base of the skull is then parallel to the angled CR.
- Ensure no rotation of the head or thorax.
- Suspend respiration; the patient should not swallow during the exposure.
Position & centering point
Enters at the level of the lower margin of the thyroid cartilage; the angled CR passes through C4. Centre the IR to the CR.
Central ray
20° cephalad erect (15° supine or with less lordosis; a kyphotic patient needs more than 20°), entering at the level of the lower margin of the thyroid cartilage to pass through C4.
Exposure / technique
- kVp
- 85
- mAs
- DR 3.2 / CR 6.3
- SID
- 40" (102 cm)
- Notes
- Cephalad angle opens intervertebral disc spaces. Sample technique: DR 3.2 / CR 6.3 mAs at 85 kVp, 40 in SID, for an 11 cm part (Merrill's sample chart). Adjust for your equipment.
kVp and mAs are sample values. Use caution when applying them in your department.
Image-quality criteria
- C3 to T2 vertebral bodies and disc spaces clearly seen.
- Intervertebral disc spaces open and symmetrical.
- Spinous processes visible midline.
- No rotation: spinous processes and SC joints (if visible) equidistant from the lateral borders of the column.
- Mandible and skull base superimposed over C1-C2.
Common errors
- 1 Insufficient cephalad angle closes disc spaces.
- 2 Excessive cephalad angle obscures lower vertebrae.
- 3 Head rotation shifts lateral masses off symmetry.
- 4 CR not centered to C4 misses pathology.
- 5 Too little cephalad angle leaves the disk spaces poorly shown (15° supine, 20° erect).
- 6 Kyphotic patient given 20° or less: Bontrager calls for more than 20°.
- 7 Head or thorax rotation moves the spinous processes off center.
- 8 CR not entering at the lower margin of the thyroid cartilage does not pass through C4.
Clinical indications
- Pathology of the mid and lower cervical spine (C3 to C7).
- Suspected fracture of C3-C7 vertebrae.
- Clay shoveler's and compression fractures, and herniated nucleus pulposus.