Download Extraoral Imaging

Chapter 23
Extraoral Imaging
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
Dental Radiography
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Questions
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What equipment is used in extraoral imaging?
What is the purpose of each of the projections that
is used for skull imaging?
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Dental Radiography
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Chapter 23 Reading
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Iannucci & Howerton (pp. 274-289)
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Dental Radiography
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Chapter 23 Outline
Extraoral Imaging
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Basic concepts
 Step-by-step procedures
 Extraoral projection techniques
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Introduction
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Iannucci & Howerton (p. 274)
Purpose
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To present the basic concepts of extraoral imaging
and describe the necessary patient and equipment
preparations
To introduce a number of extraoral projection
techniques and describe the receptor placement,
patient positioning, and beam alignment for such
projections
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Basic Concepts
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Iannucci & Howerton (pp. 274-275)
Extraoral radiograph
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An image that is placed outside the mouth during
x-ray exposure
Used to image large areas of the skull or jaws
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Purpose and Use
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Iannucci & Howerton (p. 275)
To evaluate large areas of the skull or jaws
To evaluate growth and development
To evaluate impacted teeth
To detect diseases, lesions, and conditions of
the jaws
To examine the extent of large lesions
To evaluate trauma
To evaluate the temporomandibular joint area
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Equipment
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Iannucci & Howerton (p. 275)
X-ray unit
Film
Intensifying screens
Cassette
Grid
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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X-ray Unit
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A standard intraoral x-ray machine may be
used for a variety of extraoral projections.
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Iannucci & Howerton (p. 275) (Figs. 23-1, 23-2)
Special head positioning and beam alignment
devices can be added.
Some panoramic x-ray units can be used for
extraoral projections.
The panoramic tubehead is used in
conjunction with a special extension arm and
a device known as a cephalostat or
craniostat.
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Film
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Most extraoral exposures are made with
screen film placed in a cassette with
intensifying screens.
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Iannucci & Howerton (pp. 275-276)
Screen film is sensitive to the light emitted from
intensifying screens.
An occlusal film is a nonscreen film that may
be used for some extraoral radiographs.
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Intensifying Screens
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Iannucci & Howerton (p. 276)
A device that converts x-ray energy into
visible light; the light, in turn, exposes the
screen film
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The screen film must be compatible with the light
emitted from the screen.
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Cassette
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Iannucci & Howerton (p. 276)
Purpose is to hold the receptor in tight contact
with the intensifying screen and to protect the
film from exposure to light.
Must be labeled to orient the finished image.
The front side is typically constructed of
plastic, back side is made of metal.
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Grid
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A device used to reduce the amount of
scatter radiation that reached an extraoral
film during exposure
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Iannucci & Howerton (p. 276) (Fig. 23-3)
A series of thin lead strips embedded in a material
that permits passage of the x-ray beam
The grid is placed between the patient’s head
and the film.
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During exposure, the grid permits passage of the
x-ray beam between the lead strips.
Scatter radiation is absorbed by the lead strips
and does not reach the surface of the film.
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Step-by-Step Procedures
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Equipment Preparation
Patient Preparation
Patient Positioning
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Step-by-step Procedures
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Infection control procedures must be
complete before exposing an extraoral
receptor.
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If an extraoral unit with cephalostat is used, the
ear rods must be wiped with disinfectant between
patients.
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Equipment Preparation
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Iannucci & Howerton (p. 276) (Procedure 23-1)
Load the extraoral cassette in the darkroom
under safelight conditions.
Set the exposure factors according to the
manufacturer’s recommendations.
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Patient Preparation
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Iannucci & Howerton (pp. 276-277) (Procedure
23-2)
Explain the radiographic procedure to the
patient.
Place a lead apron without a thyroid collar
over the patient and secure it.
Remove all objects from the head and neck
region that may interfere with exposure.
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Patient Positioning
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Varies with each extraoral radiographic
projection
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Discussed in section on specific extraoral
projection techniques
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Extraoral Projection Techniques
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Iannucci & Howerton (pp. 277-278) (Table 23-1)
Lateral Jaw Imaging
Skull Imaging
Temporomandibular Joint Imaging
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Lateral Jaw Radiography
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Iannucci & Howerton (pp. 277)
Used to examine the posterior region of the
mandible
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Includes
• Body of the mandible projection
• Ramus of the mandible projection
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Body of the Mandible
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Purpose
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To evaluate impacted teeth, fractures, and lesions
located in the body of the mandible
Receptor placement
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Iannucci & Howerton (pp. 277, 279) (Fig. 23-4)
Flat against cheek
Centered over body of mandible
Head position
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Tipped 15 degrees toward side being imaged
Chin extended and elevated
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Body of the Mandible
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Beam alignment
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Below inferior border of mandible, vertical
angulation -15 to -20 degrees
Perpendicular to horizontal plane of cassette
Exposure factors
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Vary with the receptor, intensifying screens, and
equipment used
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Ramus of the Mandible
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Purpose
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To evaluate impacted third molars, large lesions,
and fractures that extend into the ramus of the
mandible
Receptor placement
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Iannucci & Howerton (pp. 277, 280) (Fig. 23-5)
Flat against cheek, centered over ramus of
mandible
Head position
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Tipped 15 degrees toward side being imaged
Chin extended and elevated
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Ramus of the Mandible
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Beam alignment
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Posterior to third molar area
Vertical angulation -15 to -20 degrees
Exposure factors
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Vary with the receptor, intensifying screens, and
equipment used
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Skull Imaging
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Iannucci & Howerton (pp. 277-278)
Used to examine the bones of the face and skull
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Used most often in oral surgery and orthodontics
 Includes:
• Lateral cephalometric projection
• Posteroanterior projection
• Waters projection
• Submentovertex projection
• Reverse Towne projection
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Lateral Cephalometric Projection
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Purpose
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Iannucci & Howerton (pp. 278, 281) (Fig. 23-6)
To evaluate facial growth and development,
trauma, and disease and developmental
abnormalities
Receptor placement
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Cassette perpendicular to the floor
 Long axis of cassette horizontal
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Lateral Cephalometric Projection
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Head position
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Beam alignment
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Left side of patient’s head near cassette
Midsagittal plane perpendicular to the floor
Frankfort plane parallel to the floor
Central ray perpendicular to the cassette
Exposure factors
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Vary with the receptor, intensifying screens, and
equipment used
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Posteroanterior Projection
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Purpose
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Iannucci & Howerton (pp. 282-283) (Fig. 23-7)
To evaluate facial growth and development,
trauma, and disease and developmental
abnormalities
Receptor placement
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Cassette perpendicular to the floor
 Long axis of cassette horizontal
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Posteroanterior Projection
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Head position
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Beam alignment
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Forehead and nose touch cassette
Midsagittal plane perpendicular to the floor
Frankfort plane parallel to the floor
Central ray perpendicular to the cassette
Exposure factors
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Vary with the receptor, intensifying screens, and
equipment used
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Waters Projection
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Purpose
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To evaluate the maxillary sinus area
Receptor placement
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Iannucci & Howerton (pp. 282,284) (Fig. 23-8)
Cassette perpendicular to the floor
Long axis of the cassette is vertical
Head position
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Chin touches cassette
Tip of nose ½ -1 inch from cassette
Midsagittal plane perpendicular to the floor
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Waters Projection
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Beam alignment
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Central ray through center of the head and
perpendicular to the cassette
Exposure factors
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Vary with the receptor, intensifying screens, and
equipment used
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Submentovertex Projection
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Purpose
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Iannucci & Howerton (pp. 282, 285) (Fig. 23-9)
To identify the position of the condyles,
demonstrate the base of the skull, and evaluate
fractures of the zygomatic arch
Receptor placement
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Cassette perpendicular to the floor
 Long axis of the cassette is vertical
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Submentovertex Projection
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Head position
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Beam alignment
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Head tipped back
Top of head touches cassette
Midsagittal plane and Frankfort plane
perpendicular to the floor
Central ray through center of the head and
perpendicular to the cassette
Exposure factors
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Vary with the receptor, intensifying screens, and
equipment used
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Reverse Towne Projection
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Purpose
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Iannucci & Howerton (pp. 282, 286) (Fig. 23-10)
To identify fractures of the condylar neck and
ramus area
Receptor placement
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Cassette perpendicular to the floor
Long axis of the cassette is vertical
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Reverse Towne Projection
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Head position
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Beam alignment
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Head tipped down
Mouth open wide as possible
Top of forehead touches cassette
Midsagittal plane perpendicular to the floor
Central ray through center of the head and
perpendicular to the cassette
Exposure factors
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Vary with the receptor, intensifying screens, and
equipment used
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Temporomandibular Joint Imaging
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Iannucci & Howerton (p. 282)
The joint includes the temporal bone and the
mandible.
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The glenoid fossa and articular eminence of the
temporal bone, the condyle of the mandible, and
the articular disk between the bones comprise the
TMJ.
Includes
• Transcranial projection
• Temporomandibular joint tomography
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Transcranial Projection
(Lindblom Technique)
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Purpose
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Iannucci & Howerton (pp. 282, 287) (Fig. 23-11)
To evaluate the superior surface of the condyle
and the articular eminence
Receptor placement
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Flat against patient’s ear
Centered over TMJ
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Transcranial Projection
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Head position
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Beam alignment
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Midsagittal plane perpendicular to the floor and
parallel with the cassette
2 inches above and 0.5 inch behind the ear
canal opening
Vertical angulation +25 degrees, horizontal
angulation forward 20 degrees
Exposure factors
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Vary with the receptor, intensifying screens, and
equipment used
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Temporomandibular Joint
Tomography
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Iannucci & Howerton (pp. 287-288) (Fig. 23-12)
Used to examine the temporomandibular joint
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The location of the rotational point determines
what plane of the head of the TM joint will be
imaged.
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