The difference between Chest Posterior Anterior (PA) and Anterior Posterior (AP) radiographs.

3. Why do we do Chest projection imaging PA Erect

  • The patient is positioned easily, its comfortable and they keep still because they can lean on the detector
  • It is easier to move the scapula out of the lung fields
  • We get an image of the heart with reduced magnification if we use long FRD (180cms)
    • The heart is distorted by its position in the mediastinum but you can assess the size of the heart on a PA you cannot on an AP
  • There is reduced radiation dose to the anterior radiosensitive organs
  • Respiration is more effective when standing
    • The anterior ribs are better defined to enable you to check the level of inspiration
  • Fluid levels are defined more easily with the use of a horizontal central beam