Pa(posteroanterior) cephalometry

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