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40 Cards in this Set
- Front
- Back
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why are extra oral radiographs used
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evaluation of areas not fully covered by intraoral films
visualization of the skull and structures |
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what are lead markers used for in extraoral radiographs
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left and right orientation
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give the sizes of the different extraoral films we use
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skull film - 8 X 10 inch
Panoramic - 15 X 30 cm Lateral oblique view of mandible - 5 X 7 inch |
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What is Kodak T-Mat L film in combination with Kodak Lanex screen used for
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provides good soft tissue visualization(long scale contrast)
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What is Kodak T Mat G film combined with Kodak Lanex regular screens used for
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good short scale contrast
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What are the 6 extraoral types of radiographs we can take
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Posterior-Anterior(PA)
Lateral Skull(cephalometric projection) Water's Projection Caldwell Projection Reverse-Towne's Projection Submentovertex(Axial) |
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What does a lateral oblique mandible projection portray
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mandibular body, and ramus
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What is the name of a device that can produce repeatable head positions
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cephalostat
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Describe the frankfort plane
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line from superior border to EAM(or superior border tragus) to infraorbital rim
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Describe the canthomeatal or tragocanthal line
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Center point of EAM to outer canthus of the eye
NOTE forms about a 10 degree angel to the frankfort plane |
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A technique that employs radiographic images for the purpose of making head meausurements is known as what
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Cephalometrics
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What can one study using cephalometrics
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craniofacial growth
diagnosis ortho treatment planning evaluation of treated cases |
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What are the uses of a PA cephalometric projection
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evaluate the skull, pathology, trauma, developmental abnormalities, progressive changes in mediolateral dimension, assymetrical growth, ethmoid sinuses, nasal fossas and orbits
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how should the patient be positioned during a PA cephalometric projection
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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
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How can you differentiate a PA from a caldwell
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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
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The exposure parmaters of a PA vary with what
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type of machine, source object distance and screen film combo
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What are the indications for a lateral cephalometric skull projection
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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 |
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describe the position of the patient when taking a lateral cephal. skull projection
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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
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How is soft tissue revealed on a lateral ceph. skull proj
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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
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What is another name for the Water's Projection
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Occiptomental view
USED FOR MAXILLARY SINUS SURVEY |
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What is the angle of the cantomeathal line when a Water's projection is made
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37 degree angle above the horizontal plane
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How can you tell if the patients chin needs to be tilted further on a Water's projection
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if the petrous portion of the temporal bone lies over the apex of the maxillary sinus
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what angle does the tube make with the film on a Water's projection and at what level is it taken
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CR tube should be perpendicular to film through midsaggital plane at the level of the maxillary sinus
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At what angle is the Caldwell projection in relation to the tragocanthal(canthomeatal) line
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Its at a 23 degree angle abover the tragocanthal line
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Where does the CR enter the patients head on the Caldwell projection
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about 3 cm above the occipital protuberance and it exits at glabella(whatever the hell that is)
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Where does the petrous ridge sit in relation to the orbit in a Caldwell Proj.
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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
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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
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Reverse-Towne's Projection
NOTE condyles are better viewed if pts mouth is wide open |
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What does the reverse towne's projection eliminate superimposition of
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mastoid and zygoma over the condylar neck is eliminated(superimposition occurs in PA Ceph view)
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What is the angle the canthomeatal(tragocanthal) line makes when doing a Reverse Towne's proj.
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it is oriented 25-30 degrees downward
REMEMBER THE REVERSE TOWNE'S IS AN ELONGATED SKULL "ALIEN LOOKING" RADIOGRAPH |
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how is the CR aligned when doing a reverse towne's projection
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parallel with floor and directed into film in the saggital plane thru the occipital bone
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What indications can the submentovertex projection give
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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
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How is the patient positioned for the SMV projection
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head tilted all the way back(frankfort plane parallel to film plane) with midsaggital plane of patient perpendicular to floor
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How is the CR directed on a SMV
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it is directed from below the mandible and enters midline between condyles. CR is perpendicular to film plane
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What is another name for the Mandibular Lateral Oblique Proj
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Lateral Jaw Radiograph
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What can you see in a MLO projection
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mandibular body and ramus with greater detail than panoramic
Pans replace this film but better detail is obtained thru MLO |
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What benefits does the Mandibular body projection have over pericapical films
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broader coverage
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What does the Mandibular body projection show
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pre-molar and molar region as well as inferior border of body of mandible
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how is the pt positioned for a mandibular body projection
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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
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how should you position the tube when doing a mandibular body projection
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it should be towards the 1st molar and 2cm below the angle of the mandible on the tube side
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What projection gives a view of the ramus from the angle of the mandible to condyle
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Mandibular Ramus Projection
NOTE useful for evaluation of the 3rd molar regions of max and mandible |
