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40 Cards in this Set

  • Front
  • Back
why are extra oral radiographs used
evaluation of areas not fully covered by intraoral films
visualization of the skull and structures
what are lead markers used for in extraoral radiographs
left and right orientation
give the sizes of the different extraoral films we use
skull film - 8 X 10 inch
Panoramic - 15 X 30 cm
Lateral oblique view of mandible - 5 X 7 inch
What is Kodak T-Mat L film in combination with Kodak Lanex screen used for
provides good soft tissue visualization(long scale contrast)
What is Kodak T Mat G film combined with Kodak Lanex regular screens used for
good short scale contrast
What are the 6 extraoral types of radiographs we can take
Posterior-Anterior(PA)
Lateral Skull(cephalometric projection)
Water's Projection
Caldwell Projection
Reverse-Towne's Projection
Submentovertex(Axial)
What does a lateral oblique mandible projection portray
mandibular body, and ramus
What is the name of a device that can produce repeatable head positions
cephalostat
Describe the frankfort plane
line from superior border to EAM(or superior border tragus) to infraorbital rim
Describe the canthomeatal or tragocanthal line
Center point of EAM to outer canthus of the eye

NOTE forms about a 10 degree angel to the frankfort plane
A technique that employs radiographic images for the purpose of making head meausurements is known as what
Cephalometrics
What can one study using cephalometrics
craniofacial growth
diagnosis
ortho treatment planning
evaluation of treated cases
What are the uses of a PA cephalometric projection
evaluate the skull, pathology, trauma, developmental abnormalities, progressive changes in mediolateral dimension, assymetrical growth, ethmoid sinuses, nasal fossas and orbits
how should the patient be positioned during a PA cephalometric projection
film in front of person, head centered in casssette with frankfort plane at perpendicular to film. The ray should be perpendicular to the film plane and should be in the midsaggital line of the head. MAKE SURE THE SOURCE DISTANCE FROM MIDCORONAL PLANE OF PATIENT IS 152.4 cm or 60 INCHES
How can you differentiate a PA from a caldwell
The petrous portion of the orbit will be evident in the lower 1/3 of the orbit on the PA. On the caldwell the petrous portion is below the orbit
The exposure parmaters of a PA vary with what
type of machine, source object distance and screen film combo
What are the indications for a lateral cephalometric skull projection
trauma, disease, facial growth, devel. abnorm.
pre and post treatment records for surgery, ortho and prosto.
Anterior posterior view of paranasal sinuses, mastoid air cells, nasopharyngeal soft tissues
describe the position of the patient when taking a lateral cephal. skull projection
left side pts face close to cassette, midsaggital plane parallel with film, posterior teeth in occlusion, lips at rest, frankfort plane parallel to floor. Central xray pointed toward EAM and perpendicular to film and midsaggital plane
How is soft tissue revealed on a lateral ceph. skull proj
use of a wedge filter placed on anterior side of beam, its absorbs some of the radiation which reduces beam intensity and allows soft tissue to be revealed
What is another name for the Water's Projection
Occiptomental view

USED FOR MAXILLARY SINUS SURVEY
What is the angle of the cantomeathal line when a Water's projection is made
37 degree angle above the horizontal plane
How can you tell if the patients chin needs to be tilted further on a Water's projection
if the petrous portion of the temporal bone lies over the apex of the maxillary sinus
what angle does the tube make with the film on a Water's projection and at what level is it taken
CR tube should be perpendicular to film through midsaggital plane at the level of the maxillary sinus
At what angle is the Caldwell projection in relation to the tragocanthal(canthomeatal) line
Its at a 23 degree angle abover the tragocanthal line
Where does the CR enter the patients head on the Caldwell projection
about 3 cm above the occipital protuberance and it exits at glabella(whatever the hell that is)
Where does the petrous ridge sit in relation to the orbit in a Caldwell Proj.
it is seen below orbital rim which is differs this projection from the PA ceph which shows the petrous portion of temporal lobe above orbit rim
What type of radigraph projection is used to visualize the ramus area, condylar neck fractures, the posterolateral walls of the maxillary sinus and nasal septum
Reverse-Towne's Projection

NOTE condyles are better viewed if pts mouth is wide open
What does the reverse towne's projection eliminate superimposition of
mastoid and zygoma over the condylar neck is eliminated(superimposition occurs in PA Ceph view)
What is the angle the canthomeatal(tragocanthal) line makes when doing a Reverse Towne's proj.
it is oriented 25-30 degrees downward

REMEMBER THE REVERSE TOWNE'S IS AN ELONGATED SKULL "ALIEN LOOKING" RADIOGRAPH
how is the CR aligned when doing a reverse towne's projection
parallel with floor and directed into film in the saggital plane thru the occipital bone
What indications can the submentovertex projection give
base of skull, curvature of mandible, position and orient. of condyles, sphenoid sinus, lateral walls of maxillary sinus, zygoma and any displaced fractures of zygomatic arches
How is the patient positioned for the SMV projection
head tilted all the way back(frankfort plane parallel to film plane) with midsaggital plane of patient perpendicular to floor
How is the CR directed on a SMV
it is directed from below the mandible and enters midline between condyles. CR is perpendicular to film plane
What is another name for the Mandibular Lateral Oblique Proj
Lateral Jaw Radiograph
What can you see in a MLO projection
mandibular body and ramus with greater detail than panoramic

Pans replace this film but better detail is obtained thru MLO
What benefits does the Mandibular body projection have over pericapical films
broader coverage
What does the Mandibular body projection show
pre-molar and molar region as well as inferior border of body of mandible
how is the pt positioned for a mandibular body projection
long axis of head tilted toward side being examined with mandible protruded. Cassette is held by patient against their own cheek centered over 1st molar. The cassette's lower border is supposed to be parallel with the inferior border of ramus and bottom edge should be 2cm below mandible body
how should you position the tube when doing a mandibular body projection
it should be towards the 1st molar and 2cm below the angle of the mandible on the tube side
What projection gives a view of the ramus from the angle of the mandible to condyle
Mandibular Ramus Projection

NOTE useful for evaluation of the 3rd molar regions of max and mandible