Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. Chapter 23 Extraoral...

Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.

Chapter 23Chapter 23

Extraoral ImagingExtraoral Imaging

Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc. 2

Dental RadiographyDental Radiography

QuestionsQuestions What equipment is used in extraoral imaging?What equipment is used in extraoral imaging? What is the purpose of each of the projections that What is the purpose of each of the projections that

is used for skull imaging?is used for skull imaging?



Chapter 23 Reading Chapter 23 Reading Iannucci & Howerton (pp. 274-289)Iannucci & Howerton (pp. 274-289)



Chapter 23 OutlineChapter 23 Outline Extraoral ImagingExtraoral Imaging

Basic conceptsBasic concepts Step-by-step proceduresStep-by-step procedures Extraoral projection techniquesExtraoral projection techniques


IntroductionIntroduction

Iannucci & Howerton (p. 274)Iannucci & Howerton (p. 274) PurposePurpose

To present the basic concepts of extraoral imaging To present the basic concepts of extraoral imaging and describe the necessary patient and equipment and describe the necessary patient and equipment preparationspreparations

To introduce a number of extraoral projection To introduce a number of extraoral projection techniques and describe the receptor placement, techniques and describe the receptor placement, patient positioning, and beam alignment for such patient positioning, and beam alignment for such projectionsprojections


Basic ConceptsBasic Concepts

Iannucci & Howerton (pp. 274-275)Iannucci & Howerton (pp. 274-275) Extraoral radiographExtraoral radiograph

An image that is placed outside the mouth during An image that is placed outside the mouth during x-ray exposurex-ray exposure

Used to image large areas of the skull or jawsUsed to image large areas of the skull or jaws


Purpose and UsePurpose and Use

Iannucci & Howerton (p. 275)Iannucci & Howerton (p. 275) To evaluate large areas of the skull or jawsTo evaluate large areas of the skull or jaws To evaluate growth and developmentTo evaluate growth and development To evaluate impacted teethTo evaluate impacted teeth To detect diseases, lesions, and conditions of To detect diseases, lesions, and conditions of

the jawsthe jaws To examine the extent of large lesionsTo examine the extent of large lesions To evaluate traumaTo evaluate trauma To evaluate the temporomandibular joint areaTo evaluate the temporomandibular joint area


EquipmentEquipment

Iannucci & Howerton (p. 275)Iannucci & Howerton (p. 275) X-ray unitX-ray unit FilmFilm Intensifying screensIntensifying screens CassetteCassette GridGrid


X-ray UnitX-ray Unit

Iannucci & Howerton (p. 275) (Figs. 23-1, 23-2)Iannucci & Howerton (p. 275) (Figs. 23-1, 23-2) A standard intraoral x-ray machine may be A standard intraoral x-ray machine may be

used for a variety of extraoral projections.used for a variety of extraoral projections. Special head positioning and beam alignment Special head positioning and beam alignment

devices can be added.devices can be added. Some panoramic x-ray units can be used for Some panoramic x-ray units can be used for

extraoral projections.extraoral projections. The panoramic tubehead is used in The panoramic tubehead is used in

conjunction with a special extension arm and conjunction with a special extension arm and a device known as a cephalostat or a device known as a cephalostat or craniostat.craniostat.


FilmFilm

Iannucci & Howerton (pp. 275-276)Iannucci & Howerton (pp. 275-276) Most extraoral exposures are made with Most extraoral exposures are made with

screen film placed in a cassette with screen film placed in a cassette with intensifying screens.intensifying screens. Screen film is sensitive to the light emitted from Screen film is sensitive to the light emitted from

intensifying screens.intensifying screens. An occlusal film is a nonscreen film that may An occlusal film is a nonscreen film that may

be used for some extraoral radiographs.be used for some extraoral radiographs.


Intensifying ScreensIntensifying Screens

Iannucci & Howerton (p. 276)Iannucci & Howerton (p. 276) A device that converts x-ray energy into A device that converts x-ray energy into

visible light; the light, in turn, exposes the visible light; the light, in turn, exposes the screen filmscreen film The screen film must be compatible with the light The screen film must be compatible with the light

emitted from the screen.emitted from the screen.


CassetteCassette

Iannucci & Howerton (p. 276)Iannucci & Howerton (p. 276) Purpose is to hold the receptor in tight Purpose is to hold the receptor in tight

contact with the intensifying screen and to contact with the intensifying screen and to protect the film from exposure to light.protect the film from exposure to light.

Must be labeled to orient the finished image.Must be labeled to orient the finished image. The front side is typically constructed of The front side is typically constructed of

plastic, back side is made of metal.plastic, back side is made of metal.


GridGrid

Iannucci & Howerton (p. 276) (Fig. 23-3)Iannucci & Howerton (p. 276) (Fig. 23-3) A device used to reduce the amount of A device used to reduce the amount of

scatter radiation that reached an extraoral scatter radiation that reached an extraoral film during exposurefilm during exposure A series of thin lead strips embedded in a material A series of thin lead strips embedded in a material

that permits passage of the x-ray beamthat permits passage of the x-ray beam The grid is placed between the patient’s head The grid is placed between the patient’s head

and the film.and the film. During exposure, the grid permits passage of the During exposure, the grid permits passage of the

x-ray beam between the lead strips.x-ray beam between the lead strips. Scatter radiation is absorbed by the lead strips Scatter radiation is absorbed by the lead strips

and does not reach the surface of the film.and does not reach the surface of the film.


Step-by-Step ProceduresStep-by-Step Procedures

Equipment PreparationEquipment Preparation Patient PreparationPatient Preparation Patient PositioningPatient Positioning


Step-by-step ProceduresStep-by-step Procedures

Infection control procedures must be Infection control procedures must be complete before exposing an extraoral complete before exposing an extraoral receptor.receptor. If an extraoral unit with cephalostat is used, the If an extraoral unit with cephalostat is used, the

ear rods must be wiped with disinfectant between ear rods must be wiped with disinfectant between patients.patients.


Equipment PreparationEquipment Preparation

Iannucci & Howerton (p. 276) (Procedure 23-1)Iannucci & Howerton (p. 276) (Procedure 23-1) Load the extraoral cassette in the darkroom Load the extraoral cassette in the darkroom

under safelight conditions.under safelight conditions. Set the exposure factors according to the Set the exposure factors according to the

manufacturer’s recommendations.manufacturer’s recommendations.


Patient PreparationPatient Preparation

Iannucci & Howerton (pp. 276-277) (Procedure 23-Iannucci & Howerton (pp. 276-277) (Procedure 23-2)2)

Explain the radiographic procedure to the Explain the radiographic procedure to the patient.patient.

Place a lead apron without a thyroid collar Place a lead apron without a thyroid collar over the patient and secure it.over the patient and secure it.

Remove all objects from the head and neck Remove all objects from the head and neck region that may interfere with exposure.region that may interfere with exposure.


Patient PositioningPatient Positioning

Varies with each extraoral radiographic Varies with each extraoral radiographic projectionprojection Discussed in section on specific extraoral Discussed in section on specific extraoral

projection techniquesprojection techniques


Extraoral Projection TechniquesExtraoral Projection Techniques

Iannucci & Howerton (pp. 277-278) (Table 23-1)Iannucci & Howerton (pp. 277-278) (Table 23-1) Lateral Jaw ImagingLateral Jaw Imaging Skull ImagingSkull Imaging Temporomandibular Joint ImagingTemporomandibular Joint Imaging


Lateral Jaw RadiographyLateral Jaw Radiography

Iannucci & Howerton (pp. 277)Iannucci & Howerton (pp. 277) Used to examine the posterior region of the Used to examine the posterior region of the

mandiblemandible IncludesIncludes

• Body of the mandible projectionBody of the mandible projection

• Ramus of the mandible projectionRamus of the mandible projection


Body of the MandibleBody of the Mandible

Iannucci & Howerton (pp. 277, 279) (Fig. 23-4)Iannucci & Howerton (pp. 277, 279) (Fig. 23-4) PurposePurpose

To evaluate impacted teeth, fractures, and lesions To evaluate impacted teeth, fractures, and lesions located in the body of the mandiblelocated in the body of the mandible

Receptor placementReceptor placement Flat against cheekFlat against cheek Centered over body of mandibleCentered over body of mandible

Head positionHead position Tipped 15 degrees toward side being imagedTipped 15 degrees toward side being imaged Chin extended and elevatedChin extended and elevated


Body of the MandibleBody of the Mandible

Beam alignmentBeam alignment Below inferior border of mandible, vertical Below inferior border of mandible, vertical

angulation -15 to -20 degreesangulation -15 to -20 degrees Perpendicular to horizontal plane of cassettePerpendicular to horizontal plane of cassette

Exposure factorsExposure factors Vary with the receptor, intensifying screens, and Vary with the receptor, intensifying screens, and

equipment usedequipment used


Ramus of the MandibleRamus of the Mandible

Iannucci & Howerton (pp. 277, 280) (Fig. 23-5) Iannucci & Howerton (pp. 277, 280) (Fig. 23-5) PurposePurpose

To evaluate impacted third molars, large lesions, and To evaluate impacted third molars, large lesions, and fractures that extend into the ramus of the mandiblefractures that extend into the ramus of the mandible

Receptor placementReceptor placement Flat against cheek, centered over ramus of mandibleFlat against cheek, centered over ramus of mandible

Head positionHead position Tipped 15 degrees toward side being imagedTipped 15 degrees toward side being imaged Chin extended and elevatedChin extended and elevated


Ramus of the MandibleRamus of the Mandible

Beam alignmentBeam alignment Posterior to third molar areaPosterior to third molar area Vertical angulation -15 to -20 degreesVertical angulation -15 to -20 degrees




Skull ImagingSkull Imaging

Iannucci & Howerton (pp. 277-278)Iannucci & Howerton (pp. 277-278) Used to examine the bones of the face and skullUsed to examine the bones of the face and skull

Used most often in oral surgery and orthodonticsUsed most often in oral surgery and orthodontics Includes:Includes:

• Lateral cephalometric projectionLateral cephalometric projection

• Posteroanterior projectionPosteroanterior projection

• Waters projectionWaters projection

• Submentovertex projectionSubmentovertex projection

• Reverse Towne projectionReverse Towne projection


Lateral Cephalometric ProjectionLateral Cephalometric Projection


To evaluate facial growth and development, To evaluate facial growth and development, trauma, and disease and developmental trauma, and disease and developmental abnormalitiesabnormalities

Receptor placementReceptor placement Cassette perpendicular to the floorCassette perpendicular to the floor Long axis of cassette horizontalLong axis of cassette horizontal


Lateral Cephalometric ProjectionLateral Cephalometric Projection

Head positionHead position Left side of patient’s head near cassetteLeft side of patient’s head near cassette Midsagittal plane perpendicular to the floorMidsagittal plane perpendicular to the floor Frankfort plane parallel to the floorFrankfort plane parallel to the floor

Beam alignmentBeam alignment Central ray perpendicular to the cassetteCentral ray perpendicular to the cassette




Posteroanterior ProjectionPosteroanterior Projection

Iannucci & Howerton (pp. 282-283) (Fig. 23-7)Iannucci & Howerton (pp. 282-283) (Fig. 23-7) PurposePurpose

To evaluate facial growth and development, To evaluate facial growth and development, trauma, and disease and developmental trauma, and disease and developmental abnormalitiesabnormalities

Receptor placementReceptor placement Cassette perpendicular to the floorCassette perpendicular to the floor Long axis of cassette horizontalLong axis of cassette horizontal


Posteroanterior ProjectionPosteroanterior Projection

Head positionHead position Forehead and nose touch cassetteForehead and nose touch cassette Midsagittal plane perpendicular to the floorMidsagittal plane perpendicular to the floor Frankfort plane parallel to the floorFrankfort plane parallel to the floor

Beam alignmentBeam alignment Central ray perpendicular to the cassetteCentral ray perpendicular to the cassette




Waters ProjectionWaters Projection

Iannucci & Howerton (pp. 282,284) (Fig. 23-8)Iannucci & Howerton (pp. 282,284) (Fig. 23-8) PurposePurpose

To evaluate the maxillary sinus areaTo evaluate the maxillary sinus area Receptor placementReceptor placement

Cassette perpendicular to the floorCassette perpendicular to the floor Long axis of the cassette is verticalLong axis of the cassette is vertical

Head positionHead position Chin touches cassetteChin touches cassette Tip of nose ½ -1 inch from cassetteTip of nose ½ -1 inch from cassette Midsagittal plane perpendicular to the floorMidsagittal plane perpendicular to the floor


Waters ProjectionWaters Projection

Beam alignmentBeam alignment Central ray through center of the head and Central ray through center of the head and

perpendicular to the cassetteperpendicular to the cassette Exposure factorsExposure factors

Vary with the receptor, intensifying screens, and Vary with the receptor, intensifying screens, and equipment usedequipment used


Submentovertex ProjectionSubmentovertex Projection

Iannucci & Howerton (pp. 282, 285) (Fig. 23-9) Iannucci & Howerton (pp. 282, 285) (Fig. 23-9) PurposePurpose

To identify the position of the condyles, To identify the position of the condyles, demonstrate the base of the skull, and evaluate demonstrate the base of the skull, and evaluate fractures of the zygomatic archfractures of the zygomatic arch

Receptor placementReceptor placement Cassette perpendicular to the floorCassette perpendicular to the floor Long axis of the cassette is verticalLong axis of the cassette is vertical


Submentovertex ProjectionSubmentovertex Projection

Head positionHead position Head tipped backHead tipped back Top of head touches cassetteTop of head touches cassette Midsagittal plane and Frankfort plane Midsagittal plane and Frankfort plane

perpendicular to the floorperpendicular to the floor Beam alignmentBeam alignment

Central ray through center of the head and Central ray through center of the head and perpendicular to the cassetteperpendicular to the cassette




Reverse Towne ProjectionReverse Towne Projection


To identify fractures of the condylar neck and To identify fractures of the condylar neck and ramus arearamus area

Receptor placementReceptor placement Cassette perpendicular to the floorCassette perpendicular to the floor Long axis of the cassette is verticalLong axis of the cassette is vertical


Reverse Towne ProjectionReverse Towne Projection

Head positionHead position Head tipped downHead tipped down Mouth open wide as possibleMouth open wide as possible Top of forehead touches cassetteTop of forehead touches cassette Midsagittal plane perpendicular to the floorMidsagittal plane perpendicular to the floor

Beam alignmentBeam alignment Central ray through center of the head and Central ray through center of the head and

perpendicular to the cassetteperpendicular to the cassette Exposure factorsExposure factors

Vary with the receptor, intensifying screens, and Vary with the receptor, intensifying screens, and equipment usedequipment used


Temporomandibular Joint ImagingTemporomandibular Joint Imaging

Iannucci & Howerton (p. 282)Iannucci & Howerton (p. 282) The joint includes the temporal bone and the The joint includes the temporal bone and the

mandible.mandible. The glenoid fossa and articular eminence of the The glenoid fossa and articular eminence of the

temporal bone, the condyle of the mandible, and temporal bone, the condyle of the mandible, and the articular disk between the bones comprise the the articular disk between the bones comprise the TMJ.TMJ.

IncludesIncludes• Transcranial projectionTranscranial projection• Temporomandibular joint tomographyTemporomandibular joint tomography


Transcranial Projection Transcranial Projection (Lindblom Technique)(Lindblom Technique)


To evaluate the superior surface of the condyle To evaluate the superior surface of the condyle and the articular eminenceand the articular eminence

Receptor placementReceptor placement Flat against patient’s earFlat against patient’s ear Centered over TMJCentered over TMJ


Transcranial Projection Transcranial Projection

Head positionHead position Midsagittal plane perpendicular to the floor and Midsagittal plane perpendicular to the floor and

parallel with the cassetteparallel with the cassette Beam alignmentBeam alignment

2 inches above and 0.5 inch behind the ear 2 inches above and 0.5 inch behind the ear canal openingcanal opening

Vertical angulation +25 degrees, horizontal Vertical angulation +25 degrees, horizontal angulation forward 20 degreesangulation forward 20 degrees




Temporomandibular Joint Temporomandibular Joint TomographyTomography

Iannucci & Howerton (pp. 287-288) (Fig. 23-12)Iannucci & Howerton (pp. 287-288) (Fig. 23-12) Used to examine the temporomandibular jointUsed to examine the temporomandibular joint

The location of the rotational point determines The location of the rotational point determines what plane of the head of the TM joint will be what plane of the head of the TM joint will be imaged.imaged.

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