Three-Dimensional Digital Radiography​

Cone beam computed tomography (CBCT)

An imaging technique which uses a cone-shaped x-ray beam to acquire information and present it in three dimensions.​

DICOM data

Digital Imaging and Communications in Medicine. (software)

Field of View

The area captured when performing imaging procedures.​

Multiplanar reconstruction (MPR)

the reconstruction of data in a software system creating three anatomic planes of the body.​

Axial Plane

A horizontal plane that divides the body into superior and inferior parts; runs parallel to the ground.​

Coronal Plane

A vertical plane that divides the body into anterior and posterior sides; runs perpendicular to the ground.​

Sagittal Plane

A vertical plane that divides the body into right and left sides; runs perpendicular to the ground.​

Contrast Resolution

The number of gray scale colors available for each pixel in the image.

Spatial Resolution

A measure of pixel size in multiplaner reconstruction.​

Three-dimensional Volume Rendering

A three-dimensional shape that is created from two-dimensional images.

Voxel

The smallest element of a three-dimensional image; volume element or three-dimensional pixel.​

Three-dimensional digital imaging​

• A method designed to evaluate the oral-maxillofacial 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.​

Field of View​

• The source of radiation and the digital sensor rotate around the patient and acquire multiple images of the field of view.

• Manufacturers use a variety of sizes to accommodate the field of view for diagnostic purposes.​

CBCT Machine

• 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​

Computer

• Accepts raw data and converts them into stack of planar images.​

• Technique is completed during the data reconstruction process.​

Viewing Software

• Allows dental practitioner to view axial, coronal, and sagittal images along with the three-dimensional renderings.​

Purpose and Use​ of Three-dimensional Digital Radiography

• 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

Location of Teeth in Maxilla

Example of how CBCT is used to locate unerupted teeth in the maxillary arch.​

Implant Placement

TMJ Projections

TMJ – Erosion of Left Condyle​

Panoramic Style View – Lesion in Bone​

Central-Ossifying Fibroma (Pan)​

Central-Ossifying Fibroma (CBCT)​

Impacted Tooth​

Developmental Abnormalities​

Infection and Bone Loss​

Patient Preparation​

• 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.​

Patient Positioning​

• 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.​

Advantages​

• Lower radiation dose – compared to traditional CT scans. (equivalent to three or four full-mouth series of intraoral radiographs)​

• Brief scanning time​

• Anatomically accurate images – eliminates the superimposition of structures; little or no magnification of images.​

• Ability to save and easily transport images – images can be saved to a server or compact disc, printed or emailed.​

Disadvantages​

• Patient movement and artifacts​

• Size of the field of view – field of view must be appropriate in size to capture the necessary anatomy.​

• Cost of equipment – CBCT machines range in cost from $150,000. to $300,000. Time and dedication needed to become fully acquainted with the imaging software and correctly interpret and use the images generated.​

• Lack of training in interpretation of image on data on areas outside the maxilla and the mandible.​