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POSTEROANTERIOR SKULL PROJECTION
PA cephalometric projection
second most common skull radiograph used in dentistry evaluation of facial asymmetries assessment of orthognathic surgery outcomes involving the patient’s midline or mandibular-maxillary relationship
Image Receptor and Patient Placement
image receptor is placed in front of the patient patient is placed so that the canthomeatal line forms a 9-degree angle with the horizontal plane Frankfurt plane is perpendicular to the image receptor For the standard PA skull projection, the canthomeatal line is perpendicular to the image receptor.
Position of Central X-Ray Beam
perpendicular to the image receptordirected from the posterior to the
anteriorcentered at the level of the bridge of
the nose
Resultant Image
The midsagittal plane should divide the skull image into two symmetric halves. The superior border of the petrous ridge should lie in the lower third of the orbit
Interpretation
The end
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