Extra Oral Radio Graph

8/3/2019 Extra Oral Radio Graph

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Extraoral

RadiographyProfessor Nancy Rivaldo

Monroe Community College


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Considerations

Define extraoral

Indications for use of extraoral

Define cassette

What is an intensifying screen? Advantage and disadvantage of

intensifying screens

What is screen film?

How is speed/intensification

determined?


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Cont.

What is a grid?

What are the 7 common extraoral

exposures?

What is a cephalometricradiograph?

What are two extraoral exposures

commonly used in cephalometrics?

What is the best extraoralexposure for maxillary sinus?


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Cont.

What is sialography?

What techniques are used to

examine the TMJ?


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Extraoral Film packet or cassette placed

outside oral cavity

Advantages

--usually easier than intraoral

--minimal equipment needed

Indications for use

--patient has limited opening

--area to be viewed is larger thencan be seen on intraoral

radiograph


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Cassette

Light-tight container in which film

placed

Rigid or flexible

Flat or curved

Varying sizes

Should have L or R

identification for orientation of

images in relation to patient


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Cassette--cont.

Tubeside of cassette placed

toward head

Radiation enters film from opposite

side


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Intensifying Screens Intensify or increase radiation

Decrease exposure time

Coated with a fluorescence

substance Material responsible for

fluorescence called phosphors

Phosphors emit light when

irradiated


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Phosphors Type of phosphor plays role in

speed or intensification

Calcium tungstate produces blue

light

Rare earth elements sensitive to

light in green portion of light

spectrum

Rare earth elements more efficientin converting x-ray energy into light


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Screen Composition

BASE

PHOSPHOR LAYER

REFLECTIVE LAYER

PROTECTIVE COATING


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BASE

Structural component upon which

other screen elements are applied

Made of polyester

Provides rigidity to the screen


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REFLECTIVE LAYER

Coating of white titanium dioxide

Reflects stray light back to x-ray

film

Increases efficiency and sensitivity

Contributes to dose reduction


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PHOSPHOR LAYER

Contains phosphor materials that

fluoresce

Emit visible light when irradiated


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Screen Film Used with intensifying screen (film

placed between two intensifying

screens in cassette holder)

Cassette irradiated, screens

convert x-ray energy into light,

which in turn exposes screen film

This additional mean of exposing

film = intensifying =decrease

radiation to patient

Indirect imaging


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GridUsed to prevent scattered radiationfrom reaching film

Series of narrow lead strips

separated by spaces of low-densitymaterial

Act as cleaning device to improve

image contrast


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Lateral Oblique (LateralJaw)

Film positioned lateral to jaw on

side of patients face to be

examined

Used with children and patientswith limited jaw opening

Examines posterior region of

mandible

View fractures, impactions, salivarystones in floor of mouth


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Lateral Skull

Lateral view of entire skull

Primary use = cephalometrics:

--assess patient profile

--assist in predicting jaw growthpattern

--used for measuring arch size

changes

Can also view fractures and

pathologic conditions


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Lateral Sinus

Modification of lateral skull

Used to examine growths,

infections or foreign bodies in

maxillary sinus


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Posteroanterior of Skull

Shows entire skull in posterior-

anterior plane

Primary use = cephalometrics

--measure skull growth

--observe growth abnormalities

Used to view fractures and

pathologic conditions of skull in

frontal plane


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Posteroanterior of

Mandib

le Shows entire mandible in frontal

plane

Used to localize impactions,

fractures and pathologic conditions


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Posteroanterior of Sinus

Referred to as Waters View

Best projection for maxillary sinus

Used to view fractures of maxilla,

malar bone and zygomatic arch


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Submental Vertex

See structures as if viewer looking

upward from under patients chin

Can view condylar heads, base ofskull and sphenoid sinus

Used to view fractures and

displacements of zygomatic arch


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Cephalometry

Extraoral radiographs of head used

for making skull measurements

Purpose is to correlate skeletalgrowth with tooth development and

position

Lateral skull and posteroanteriorprojection of skull most commonly

used in ortho surveys


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Hand-Wrist Films

Used to correlate chronologic age

with:

--skeletal age and development

--dental aged and development Based on principle that these

bones are good indications of

skeletal maturation due to the

many centers of ossification in thisarea


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TMJ Survey

TMJ tomography = radiographictechnique to examine joint

Other radiographs (pan) will showthe bone and relationship of joint

components only (erosions, bony

deposits)


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Arthrography

Used for imaging soft tissue

components of TMJ

Radiopaque die injected into jointspace

View condyle, glenoid fossa and

joint space


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Transcranial TMJ

Radiograph taken through or

across the skull or cranium

Lindblom technique most common

Shows glenoid fossa andrelationship to condyle


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Sialography

Examination of salivary gland

Uses radiopaque dye injected into

ducts

Initial radiograph taken followed bysuccessive radiographs to

visualize draining of gland

Documents

Extra Oral Radio Graph