Chest PA is a radiography positioning projection of the Thorax. Upright PA chest. SID 72". Inspiration on second breath. The centering point is located level of T7, 7 to 8 inches (18 to 20 cm) below the vertebra prominens or at the inferior angle of the scapula, at the midsagittal plane. The central ray is horizontal, perpendicular to IR, centered to the midsagittal plane at the level of T7. Image-quality criteria include both lungs visualized in entirety, apex to costophrenic angles, a minimum of 10 posterior ribs visible above the diaphragm. A sample technique is 120 kVp with DR 1.4 or CR 2.8 mAs, at an SID of 72 inches (183 cm).
Watch the setup
All steps (5)
- Position patient erect facing the upright Bucky.
- Place hands on the lower hips, palms out, and roll shoulders forward.
- Chin raised and resting against the IR.
- Shoulders depressed to move the clavicles below the apices.
- Midcoronal plane parallel to the IR (no rotation); midsagittal plane centered to the CR.
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
- Entire lungs from apex to costophrenic angle.
- Heart and mediastinum with less magnification than AP.
- Thoracic vertebrae and ribs.
- Air-filled trachea from T1 down.
- Diaphragm and costophrenic angles.
- Clavicles and sternoclavicular joints.
Patient preparation
- Verify patient identity using two identifiers.
- Remove all radiopaque objects from the chest area.
- Confirm pregnancy status for female patients of child-bearing age.
- Explain breathing instructions: inspiration on the second breath in, hold.
- Position patient erect facing the upright Bucky.
- Place hands on the lower hips, palms out, and roll shoulders forward.
- Chin raised and resting against the IR.
- Shoulders depressed to move the clavicles below the apices.
- Midcoronal plane parallel to the IR (no rotation); midsagittal plane centered to the CR.
Position & centering point
Level of T7, 7 to 8 inches (18 to 20 cm) below the vertebra prominens or at the inferior angle of the scapula, at the midsagittal plane.
Central ray
Horizontal, perpendicular to IR, centered to the midsagittal plane at the level of T7.
Exposure / technique
- kVp
- 120
- mAs
- DR 1.4 / CR 2.8
- SID
- 72" (183 cm)
- Notes
- High-kVp technique. Grid required. Reduces cardiac magnification compared to AP. Sample technique: DR 1.4 / CR 2.8 mAs at 120 kVp, 72 in SID, for a 22 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
- Both lungs visualized in entirety, apex to costophrenic angles.
- A minimum of 10 posterior ribs visible above the diaphragm.
- Sternoclavicular joints equidistant from the spine (no rotation).
- Scapulae rotated laterally and clear of the lung fields.
- Clavicles symmetric and in the same horizontal plane, lying below the lung apices (shoulders depressed).
- Sharp diaphragm and vascular markings (no respiratory motion).
- Trachea visible in the midline.
Common errors
- 1 Rotation leaves the sternoclavicular joints at unequal distances from the spine.
- 2 Chin not raised enough causes superimposition of mandible over apices.
- 3 Inadequate inspiration elevates the diaphragm and crowds the lung bases.
- 4 Off-centered CR clips the lung apices or costophrenic angles.
- 5 Failure to roll shoulders forward leaves scapulae over the lung fields.
Clinical indications
- Routine evaluation of pulmonary and cardiac pathology.
- Pleural effusion, pneumothorax, atelectasis and signs of infection.