Ribs PA Oblique is a radiography positioning projection of the Thorax. PA oblique ribs, 45-degree. SID 40". Full inspiration. The centering point is located level of t7. patient in 45-degree anterior oblique (rao/lao), anterior chest toward the ir.. The central ray is perpendicular to ir, horizontal at t7.. Image-quality criteria include anterior ribs of the affected side projected clear of the vertebral column., ribs projected parallel without foreshortening or overlap.. Standard exposure ranges from 65 to 75 kVp, 12 to 20 mAs, at an SID of 40 inches (102 cm).
Anatomy demonstrated
- Axillary ribs of the affected side 1-12.
- Costochondral junctions and costal cartilages.
- Intercostal spaces.
- Thoracic vertebral bodies.
- Sternum and sternal articulations.
- Diaphragm.
Patient preparation
- Verify patient identity using two identifiers.
- Remove all radiopaque objects from the chest and trunk.
- Position patient in 45-degree oblique facing away from tube.
- Affected side rotated away from the IR.
- Instruct patient to take a deep breath in and hold.
Position & centering point
Level of T7. Patient in 45-degree anterior oblique (RAO/LAO), anterior chest toward the IR.
Central ray
Perpendicular to IR, horizontal at T7.
Exposure / technique
- kVp
- 65–75
- mAs
- 12–20
- SID
- 40" (102 cm)
- Notes
- Grid required. Affected side closest to IR. Full inspiration held.
Image-quality criteria
- Anterior ribs of the affected side projected clear of the vertebral column.
- Ribs projected parallel without foreshortening or overlap.
- All ribs from above diaphragm to below demonstrated.
- Costochondral junctions visible and clear.
- Minimal overlap of ribs from the opposite side.
- Costophrenic angle clearly defined.
Common errors / ARRT traps
- 1 Inadequate obliquity fails to project ribs clear of the spine.
- 2 Excessive obliquity foreshortens the ribs and distorts anatomy.
- 3 Affected side not raised prevents visualization of anterior ribs.
- 4 Inadequate inspiration limits the rib and diaphragm visualization.
- 5 Forward or backward rotation aligns ribs instead of separating them.
Clinical indications
- Evaluation of anterior rib fractures.
- Assessment of rib pathology not clearly visible on AP or PA.
- Detailed visualization of costochondral junctions on the affected side.
- Follow-up imaging of anterior rib trauma.
Aligned to the 2025 ARRT Content Specifications.