What patient breathing instructions maximize the amount of air in the lungs on the PA projection of the chest?

The best patient breathing instruction to maximize the amount of air in the lungs on the PA projection of the chest is to have the patient take a deep inhalation and then hold their breath at the end of this inspiration. This technique allows the lungs to be fully expanded, which results in better visualization of the lung fields and thoracic structures on the X-ray image.

When the lungs are fully inflated, the radiograph captures a clearer image of the cardiac silhouette, pulmonary vasculature, and lung parenchyma, which provides essential information for clinical diagnosis. Instructing the patient to hold their breath after a second deep inspiration also helps prevent motion blur, contributing to a higher quality image.

Other choices, while they may seem reasonable, do not optimize lung inflation in the same way. Breathing normally throughout the procedure will not allow the lungs to be fully inflated during the imaging process. Stopping breath at the end of exhalation would lead to diminished lung volume on the radiograph, which is not ideal, as it could obscure important details.