Download Chapter 7 Body Systems

Chapter 26
Three-Dimensional Digital 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 are the basic concepts and indications of
three-dimensional digital imaging?
What equipment is used?
What are advantages and disadvantages of digital
radiography?
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Basic Concepts
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Eliminates deficiencies
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Provides more detailed information
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Terminology
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Cone beam computed tomography (CBCT)
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Cone beam volume tomography (CBVT)
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Computer assisted digital imaging in dentistry that uses
cone shaped x-ray beam to acquire information and
present it in three dimensions
Term used to differentiate between dental and medical
CT
DICOM data
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The way data is formatted for handling, storing and
transmitting three-dimensional images
Acronym: digital imaging and communications in
medicine
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Terminology
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Field of view: area that can be captured in image
Multiplanar reconstruction (MPR): raw data
imported into viewing software to create three
anatomic planes
Plane, axial: Horizontal plane
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Plane, coronal: Vertical plane
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Divides body into superior and inferior parts; runs parallel
to floor
Divides body into anterior & posterior sides; runs
perpendicular to the ground
Plane, sagittal: Vertical plane
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Divides body into right and left sides; runs perpendicular
to the ground
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Terminology
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Resolution, contrast
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Resolution, spatial
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Image that demonstrates the anatomy in 3D
Three-dimensional volume rendering
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Measurement of pixel size in multiplanar reconstruction
Three-dimensional digital imaging
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Number of gray scale colors available for each pixel
A 3D shape that is created from 2D images
Voxel: AKA: volume element or 3D pixel
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Smallest element of a 3D image
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Fundamentals
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Three-dimensional digital imaging
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A method designed to evaluate the oralmaxillofacial complex
Named because it uses a cone-shaped x-ray
beam to acquire three-dimensional information
Source of radiation rotates around the head of the
patient very similar to a panoramic machine
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Fundamentals
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DICOM images
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These allow practitioner to see field of view in
three dimensions.
They are viewed in three planes: axial plane,
coronal plane, and sagittal plane.
When viewed together images are referred to as
multiplanar reconstructed images.
They can be shared amongst dental professionals.
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Equipment
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Specialized equipment
CBCT Machine
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Comparable in size to a panoramic machine
 Patient sits, stands, or is placed in a supine
position.
 In one rotation, radiation and receptor capture field
of view
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Equipment
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Computer
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Accepts raw data and converts them into stack of
axial images.
Technique is completed during the data
reconstruction process.
Viewing Software
Allows dental practitioner to view axial,
coronal, and sagittal images.
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Purpose and Use
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Greatly improve interpretation, diagnosis, and
treatment planning of dental care
Implant placement
Extraction or exposure of impacted teeth
Definition of anatomic structures
Endodontic assessment
Airway and sinus analysis
Evaluation of temporomandibular joint (TMJ)
disorders
Orthodontic evaluation
Pathology evaluation
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Step-by-Step Procedures
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It is critical to refer to the manufacturerprovided instruction booklet for information
concerning the operation of the system,
equipment preparation, patient preparation,
and exposure.
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Patient Preparation
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Patients may be asked to sit or stand or be
placed in the supine position during radiation
exposure.
Instructions are given to the patient before
exposure to remove jewelry, eyeglasses, and
removable dental appliances.
A guide may be placed in the patients mouth
during the scanning process.
Some specialists may ask that the upper and
lower teeth be kept apart.
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Patient Positioning
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Patient is instructed to remain still.
Scan times vary from 7 to 30 seconds.
Ergonomic head and chin supports have
been designed for improved patient comfort.
Laser beams may be installed to help with
proper alignment of clinical structures and to
ensure correct anatomic positioning.
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Advantages of Three-Dimensional Imaging
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Lower radiation dose compared to traditional
CT scans; greater than full mouth dose
Brief scanning time
Anatomically accurate images: 1:1
relationship with anatomy; no magnification
Ability to save and easily transport images:
able to be saved as jpg or bmp
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Very easy to send to other doctors
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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Disadvantages of Digital Radiography
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Patient movement and artifacts: metals may
causes areas of blockage on image
Size of the field of view: if too small areas of
importance may be missed
Cost of equipment: $150,000 to $300,000
Lack of training in interpretation of image on
data on areas outside the maxilla and the
mandible
Copyright © 2012, 2006, 2000, 1996 by Saunders, an imprint of Elsevier Inc.
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