AP Thoracic is a radiography positioning projection of the Spine. Supine, arms at sides, CR perpendicular to T7. Grid required. The centering point is located T7 vertebra (mid-chest), 3-4 inches below the jugular notch. The central ray is perpendicular to IR at T7 level. Image-quality criteria include all thoracic vertebrae T1-T12 visualized, intervertebral joint spaces shown. A sample technique is 90 kVp with DR 8 or CR 20 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Thoracic vertebral bodies T1-T12.
- Intervertebral disc spaces.
- Spinous processes.
- Transverse processes of the thoracic vertebrae.
- Costovertebral articulations.
Patient preparation
- WARNING: with possible spinal injury or severe trauma, do not attempt to move the patient (Bontrager). A physician reviews the horizontal-beam lateral before this AP (Bontrager, Merrill's).
- Verify patient identity using two identifiers.
- Remove jewelry and radiopaque objects from the area being imaged.
- Supine on table in neutral alignment.
- Arms at the sides.
- Flex the hips and knees to reduce the thoracic curvature.
- Suspend respiration on expiration.
Position & centering point
T7 vertebra (mid-chest), 3-4 inches below the jugular notch.
Central ray
Perpendicular to IR at T7 level.
Exposure / technique
- kVp
- 90
- mAs
- DR 8 / CR 20
- SID
- 40" (102 cm)
- Notes
- Grid required. Supine position at end of full expiration. Sample technique: DR 8 / CR 20 mAs at 90 kVp, 40 in SID, for a 21 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
- All thoracic vertebrae T1-T12 visualized.
- Intervertebral joint spaces shown.
- Spinous processes aligned vertically.
- No rotation: sternoclavicular joints equidistant from the spine.
- Spinal column from C7 to L1 centered to the midline of the IR.
Common errors
- 1 Body rotation leaves the sternoclavicular joints at unequal distances from the spine.
- 2 CR misalignment off T7 misses mid-thoracic region.
- 3 Inspiration instead of expiration: expiration reduces thoracic air for more uniform brightness and density.
Clinical indications
- Pathology of the thoracic spine, such as subluxation or kyphosis.
- Suspected compression fracture assessment.