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 disc spaces symmetrically open.. Standard exposure ranges from 75 to 85 kVp, 25 to 40 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Thoracic vertebral bodies T1-T12.
- Intervertebral disc spaces.
- Spinous processes in profile.
- Lateral processes and facet joints.
- Thoracic kyphotic curve.
Patient preparation
- Verify patient identity using two identifiers.
- Remove jewelry, bra with metal fasteners, and objects.
- Supine on table in neutral alignment.
- Arms at sides or folded across chest.
- Shoulders relaxed away from neck.
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
- 75–85
- mAs
- 25–40
- SID
- 40" (102 cm)
- Notes
- Grid required. Supine position at end of full expiration.
Image-quality criteria
- All thoracic vertebrae T1-T12 visualized.
- Intervertebral disc spaces symmetrically open.
- Spinous processes aligned vertically.
- No rotation evidenced by symmetric lateral processes.
- Entire chest field included.
Common errors / ARRT traps
- 1 Body rotation shifts lateral processes off symmetry.
- 2 Shoulder elevation obscures upper thoracic vertebrae.
- 3 CR misalignment off T7 misses mid-thoracic region.
- 4 Inspiration distorts disc spaces and vertebral height.
Clinical indications
- Thoracic spine trauma survey in supine patient.
- Evaluation of spondylosis or arthrosis.
- Suspected compression fracture assessment.
- Post-operative thoracic fusion follow-up.
Aligned to the 2025 ARRT Content Specifications.