Download Welcome to Radiology

Principles of Dental Imaging
RVT: Chapter 10
CTVT: pg. 1315- 1321
Objectives: Dental Imaging
• Describe the dental x-ray unit
• Explain the use of dental x-rays
• Understand the basics of dental film
• Explain the methods for dental film processing
• Know the differences between types of dental radiography
Why Dental Imaging?
• To see pathology below gingiva or inside
tooth
• To evaluate missing teeth
• For client communication/education
• Medical/legal documentation
• Postoperative extraction confirmation
• Follow progression of pathology or
periodontal disease
• Pre-purchase exams for show dogs
Why Do We Image Teeth?
• Periodontal disease is a common
ailment in small animals.
• Isolating origin/extent without
radiographs is difficult
• The x-ray shows lesions above
AND below the gum line.
• Dental radiographs become part
of your patient’s permanent
medical record.
• Survey rads are good to have
BEFORE disease process begins
When to Take Dental Radiographs
• Tooth mobility
• Gingival bleeding
• Nasal discharge
• Oral swelling
• Tooth is fractured
• Tooth is discolored
• Gingival recession/bone exposure is
•
•
•
•
present
Teeth are missing
Prior to extraction - anatomical
orientation and documentation
Post extraction
During endodontics
Dental Radiography: Overview
• Includes both intraoral and extraoral rads
• Special equipment not essential
• X-ray machine
• Dental x-ray machine
• Allows thorough evaluation of tooth & periodontium
• Remember what makes up the periodontium?
• Types of dental imaging:
• Film
• CR
• DR
Regular X-ray Machine
Intraoral: Film inside the mouth
Regular Machine - Intraoral
Extraoral: Film outside the mouth
Regular Machine - Extraoral
Dental Radiography Unit
9
Parts of a Dental Radiography Unit
X-ray Tube
• Stationary anode
• Advantage?
• Disadvantage?
• No collimator light
• Can be angled directly over
anatomy
Extension cone (PID)
• Lead lined
• Variable lengths
10
Parts of a Dental Radiography Unit
• Generator/Control Panel
• Contains timer and kVp/mA
regulators
• kVp usually pre-set around 70
• mA usually pre-set at 7 or 8
• Time is variable: set by operator
• Should have a technique chart near
the generator
• Some systems have preset settings
for dogs, cats, exotics
11
Radiation Safety - Dental
• Technician should stand behind a barrier whenever
possible…however…
• Very minimal exposure to personnel when using dental machine
• Why is this?
• Never stand directly in front of or behind the tube head
• Film should never be held in patient’s mouth while
radiograph is taken
• Dosimeters should be worn
• Machine should be inspected annually
Film Imaging
• Intraoral film is used in dental radiography
• Inexpensive, flexible, and provides good detail
• No intensifying screen
• Can achieve high definition with dental film due to
infinite resolution
• Measured in line pairs/mm
• Requires higher technical factors
• Film is individually packaged
• No cassette or film box needed
• Store away from radiation!
Dental Film
Individual dental films are packaged
in a light-tight plastic envelope and
contain:
The film
2. Paper folder/packing card
3. Lead foil backing- prevents
scatter radiation from affecting
film
1.
4. Tab opening in back for film
removal
• Packets are color-coded:
• Green: single film packet
• Gray: two-film packet
Dental Film
• Speeds
• D (ultra speed)
• Used most commonly in veterinary
dentistry
•E
• Twice as fast as D film
• Requires half the exposure
Dental Film
• Sizes used most often in
small animal veterinary
dentistry:
• Size 0 – Cats, exotics
• Size 2 (standard size) –
Used most
• Size 4 – Larger teeth,
occlusal surfaces
16
Film Dot
• Dental film is embossed
with a raised dot in one
of the corners.
•
Convex side towards the
beam
(White side)
•
Concave side away from
the beam
• Dot is always positioned
rostral.
Film Processing
1. Manual
• Chairside darkroom
2. Automatic
• Standard radiography processor
• Can be used by attaching dental film to leader film
• Film can become unattached and get lost…not ideal
• Dental processors are available!
• Efficient & consistent
• Work on roller transport system
• Usually not feasible unless large volume practice
Chairside Darkroom
19
Film Labeling & Storage
• Images are part of patient’s medical record
• Each image must be identified with permanent marker
• Store individually in mini envelopes
• Teeth must be identified correctly!
• Well-processed film is of good archival quality
Computerized Dental Radiography
• Image receptor is plastic covered, flexible phosphor plate
• Will need to be replaced over time
• Available in many sizes
• Processing requires a reader
Digital Dental Imaging
• Image receptor is a sensor pad that captures image and
transfers it to a computer screen
• Sensor is not flexible and limited on sizes
CR and DR Imaging
• Recent in veterinary medicine
(last 10 years or so)
• Advantages & disadvantages similar to non-dental
radiography
• Can use the same x-ray unit as film
• Hand held units require more training
• May be cost-prohibitive (unless high volume)