PA and lateral chest

Patient and part

The routine chest is a PA and a left lateral, taken erect at 72 inches, or 183 cm. Erect lets the diaphragm drop and shows air-fluid levels. The 72-inch SID and the heart close to the receptor reduce magnification of the heart. For the PA, the patient faces the receptor with the chin raised, hands on the hips with palms out, and shoulders rolled forward and pressed down. Rolling the shoulders forward moves the scapulae out of the lung fields, and pressing them down moves the clavicles below the apices. For the lateral, the left side is against the receptor to reduce heart magnification, with the arms raised over the head.

Central ray

The central ray is perpendicular and centered at the level of T7, about 7 to 8 inches below the vertebra prominens, which puts it near the inferior angle of the scapulae. For the lateral, center at the same T7 level in the midcoronal plane. Expose at the end of the second full inspiration, because the second breath is deeper and is held without strain.

What a good image shows

On a good PA, at least 10 posterior ribs show above the diaphragm, the apices and both costophrenic angles are included, and the scapulae are outside the lung fields. No rotation means the medial ends of the clavicles are equidistant from the spinous processes. On a good lateral, the posterior ribs are superimposed, the sternum is in profile, and the arms are clear of the apices. Because of beam divergence, the posterior ribs may be separated by up to about half an inch, or 1 cm, and still be acceptable.

Fixing it

Rotation is the classic error. On the PA, unequal distances from the medial clavicles to the spine show the patient is turned. Square the shoulders and pelvis and keep weight even on both feet. Fewer than 10 ribs means a poor inspiration, so coach the breath and expose after the second inspiration. On the lateral, posterior ribs separated more than about half an inch means rotation, so make the shoulders and hips perpendicular to the receptor.