What is the difference between a posteroanterior (PA) and an anteroposterior (AP) radiograph?
These differ based on the direction of the x-ray beam passing through a patient. A PA radiograph occurs when the x-ray beam enters from the posterior aspect of the patient and exits anteriorly to reach the x-ray detector. An AP radiograph occurs when the x-ray beam enters from the anterior aspect of the patient and exits posteriorly to reach the x-ray detector.
