brief description on PA ceph, various types, views, indications and interpretations

1. P R E S E N T E D B Y : D R . T A N I A A R S H A D
S I D D I Q U I
A S S I S T A N T P R O F E S S O R
D A T E D : 3 0 T H J A N U A R Y 2 0 2 0
POSTERO-ANTERIOR
CEPHALOMETRY

3. Learning Outcomes
 What are the different types of PA ceph
 How are PA cephs different from AP and Lateral
Ceph
 What are the structures visible on the different views
 What are the indications for the different views
 Which view is important for orthodontics
 Interpretation of PA ceph

4. AP or PA
 Abbreviation tells us how the x-ray beam travels
through the skull
PAAP

5. Why PA and not AP?
 Disadvantages of AP
 Enlarged facial bones
 Increased radiation to the eyes

6. ADVANTAGES DISADVANTAGES
 Valuable tool in assessment of right
and left structures of dentofacial
complex
 Structures are at equal distance from
x-ray source and film, so no
distortion or enlargement of image.
 Proper registration and evaluation of
left and right sides
 Difficulty in producing head
posture
 Difficulty in identifying
landmarks due to
superimposition
 Radiation exposure
PA CEPHALOGRAM

7. Postero-anterior Skull (PA Skull)
 Fractures of skull vault
 Investigation of frontal
sinuses
 Conditions affecting
cranium particularly:
 Paget’s Disease
 Multiple Myeloma
 Hyperparathyroidism
 Intracranial calcification
 Facial asymmetries
 Projection shows cranial
vault, frontal bone and
jaws
 Suitable for the assessment
of facial asymmetries and
for preoperative and
postoperative comparisons
in orthognathic surgery
involving the mandible

8. A. Positioning for the PA skull projection — the patient is in the forehead-nose position and the X-ray beam is horizontal. B
Diagram of the positioning — the radiographic baseline is horizontal and perpendicular to the film, and the X-ray beam is also
horizontal.

9. Postero- anterior of the Jaws (PA Jaws/ PA
Mandible)
 Projection shows posterior
parts of the mandible
 Fracture of mandible
 Lesions such as cysts or
tumors in posterior 1/3 of the
body OR rami, for medio-
lateral expansion
 Mandibular hypo/hyperplasia
 Maxillofacial deformities

10. A. Positioning for the PA jaws/PA mandible projection — the patient is in the forehead-nose position and
the X-ray beam is horizontal centred through the rami. B Diagram of the positioning — the radiographic
baseline is horizontal and perpendicular to the film, and the X-ray beam is also horizontal

11. Reverse Towne’s
 Shows condylar heads and
necks
 High fracture of condylar
necks
 Intra- capsular fracture of the
TMJ
 Investigation of quality of
articular surface of condylar
head in TMJ disorders
 Condylar hypo/hyperplasia

12. A. Positioning for the reverse Towne's projection — the patient is in the forehead-nose position with the mouth open and the
X-ray beam is aimed upwards at 30°. B. Diagram of the positioning — the radiographic baseline is horizontal and
perpendicular to the film, the mouth is open and the X-ray beam is aimed upwards at 30°.

13. ANALYSIS