Waters view

Last revised by Andrew Murphy on 19 Sep 2021

The occipitomental (OM) or Waters view is an angled PA radiograph of the skull, with the patient gazing slightly upwards.

It can be used to assess for facial fractures, as well as for acute sinusitis. In general, radiographs of the skull and facial bones are rapidly becoming obsolete, being replaced by much more sensitive CT scans.

  • the patient is erect facing the upright detector 
  • the chin is raised until the mento-mandibular line (MML) is perpendicular to the receptor (OML will be 37° from receptor)
  • ensure patient's head is straight
  • posteroanterior projection
  • centering point
    • the beam is exiting at the acanthion 
  • 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)
  • the petrous ridge should be inferior to the maxillary sinuses
  • assess for rotation via the assessments of the coronoid process symmetry
  • generally, the base of the mandible and the occiput will be superimposed
  • learn your skull positioning lines, it makes for reading position guides a lot easier
  • guarantee that the patient is not 'hunched' over when they are being examined. This can cause an artefact from the shoulders and the patient is more likely to be rotated; it is best to move the chair up close to the detector so they are sitting up straight for the image
  • use a side marker and regularly place in PA. Skulls can get tricky with figuring out which side is which. Many vendors tend to 'flip' images to make them appear AP

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Cases and figures

  • Figure 1: cranial landmarks
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  • Figure 2: skull positioning lines
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  • Case 1: normal Waters view skull x-ray
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  • Case 2: normal facial bones
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  • Case 3: with zygomatic arch fracture
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  • Case 4: orbital blowout fracture with teardrop sign
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