3. Types according to planes :
• Sagittal or median plane
Lateral ceph. / skull
• Travsverse or horizontal plane
SMV
• Coronal or frontal plane
PA ceph. / skull
Waters
Reverse-towne
4. Selection criteria:
To examine areas not fully covered by intraoral
films
To evaluate the cranium, face (including the
maxilla and mandible), or cervical
To evaluate the relationship between various oro-
facial and dental structures, growth and
development of the face, or treatment progression
• First step in obtaining and interpreting a radiograph
=> Selecting the appropriate extraoral
radiographic examination
• For spatially localizing pathology, usually at least
two radiographs taken at right angles to each
another are obtained
6. The proper Exposure parameters
depend on:
• the patient's size, Anatomy & head
orientation
• image receptor speed
• x-ray source to receptor distance
• grids +/-
Patient kV mA
Hand Wrist 60 2
Child(6 and under) 64 5
Adult Female / Small Male 66 5
Adult Male 68 5
Large Adult 70 5
7. Grids
reduce scattered radiation
improve contrast and resolution
higher patient exposure
improve the radiographic appearance of fine
structures, such as trabecular architecture
aid in the diagnosis of disease
Cephalometry does not require the use of grids
10. EVALUATION OF THE IMAGE
Extraoral images should first be evaluated for
overall quality
The first step in the interpretation of
radiographic images is the identification of
anatomy
13. LATERAL SKULL/CEPHALOMETRIC PROJECTION
Image Receptor and Patient positioning
Position of Central X-Ray Beam
• The image receptor parallel to the patient's midsagittal
plane
• The site of interest toward the image receptor ( minimize
distortion)
• In cephalometric radiography => 1. the left side toward
the image receptor 2. a wedge filter at the tube head
over the anterior aspect of the beam
• perpendicular to the midsagittal plane and
the image receptor
• centered over the external auditory
meatus
19. PA SKULL/CEPHALOMETRIC PROJECTION
PA Cephalogram
=> mainly used for evaluation of
facial asymmetries and for
assessment of orthognathic surgery
outcomes involving the patient's
midline or mandibular-maxillary
relationship
20. PA SKULL/CEPHALOMETRIC PROJECTION
Image Receptor and Patient positioning
Position of Central X-Ray Beam
• Image receptor => in front of the patient / perpendicular to the
midsagittal plane / parallel to the coronal plane
• PA cephalometric => the Canthomeatal line 9-degree with the
horizontal plane/ The Frankfurt plane perpendicular to receptor
• standard PA skull => the canthomeatal line perpendicular to
receptor
• perpendicular to the receptor from the post. to the ant.
• parallel to the patient's midsagittal plane
• centered at the level of the bridge of the nose
23. SUBMENTOVERTEX (SMV or base) PROJECTION
Image Receptor and Patient positioning
Position of Central X-Ray Beam
• Receptor parallel to the patient's transverse plane
• Perpendicular to the midsagittal and coronal planes
• The patient's neck extended as far backward as possible
• The canthomeatal line 10-degree with the receptor
• Perpendicular to the receptor
• from below the mandible toward the vertex of the skull
• 2 cm anterior to a line connecting the right and left condyles
26. WATERS PROJECTION
Image Receptor and Patient positioning
Position of Central X-Ray Beam
• The receptor in front of the patient
• Perpendicular to the midsagittal plane
• The patient's head tilted upward
• The canthomeatal line 37-degree with the image receptor
• Open mouth => the sphenoid sinus seen over the palate
• Perpendicular to the receptor
• Centered in the area of the maxillary sinuses
28. REVERSE-TOWNE PROJECTION
(OPEN MOUTH)
Image Receptor and Patient positioning
Position of Central X-Ray Beam
• The receptor in front of the patient
• Perpendicular to the midsagittal plane
• Parallel to the coronal plane
• Patient's head tilted downward
• the canthomeatal line 25 – 30 degree with the receptor
• Open mouth => improve the visualization of the condyles
• Perpendicular to the receptor
• Parallel to the patient's midsagittal plane
• Centered at the level of the condyles