Skull (PA view)

Radiopaedia • CC-by-nc-sa 3.0 • de

The skull posteroanterior (PA) view is a non-angled radiograph of the skull. This view provides an overview of the entire skull rather than attempting to highlight any one region.

Indications

This examination is able to assess for medial and lateral displacements of skull fractures, in addition to neoplastic changes and Paget disease.

Patient position

  • the patient is erect
  • the patient's forehead is placed against the image detector allowing for the nose to be in contact as well

Technical factors

  • posteroanterior projection
  • centering point
    • the beam is exiting at the nasion
  • collimation
    • superior to the skin margins
    • inferior to include the most inferior aspects of the skull
    • lateral to include the skin margin
  • orientation  
    • portrait
  • detector size
    • 24 cm x 30 cm
  • exposure
    • 75-80 kVp
    • 20-25 mAs
  • SID
    • 100 cm
  • grid
    • yes (this can vary departmentally)

Image technical evaluation

The petrous ridge will overlap the orbits, and the innominate lines should be equal distance from the lateral borders of the orbits.

Practical points

  • the PA view decreases the radiation dose to the eyes compared with the AP view
  • less magnification of the facial bones is achieved compared with the AP view
  • overlap of facial bone structures makes it harder to evaluate the sinuses than with an angled view (e.g. Caldwell view)