Panoramic Radiography Flashcards
What is an OPG?
Orthopantomogram
= Tomographic image of maxillofacial structures using a rotating x-ray source & receptor
What are the components of an extra-oral film cassette?
Modern machines use a digital receptor
Traditional OPGs had a cassette
Emulsion layer: light-sensitive silver halide crystals coated onto both sides of a transparent base material
Double sided films have increased optical density
What are intensifying screens?
Intensifying screens are used in the x-ray cassette to intensify the effect of the x-ray photon by producing a larger number of light photons. It decreases the mAs required to produce a particular density and hence decreases the patient dose significantly.
In cassettes, which use double emulsion films, two screens are used, mounted on both sides of the cassette.
What is focal trough?
The focal trough is the area in which structures will appear most sharply and clearly
Describe patient positioning
How are artefacts produced?
What are the indications for panoramic imaging?
What is the beam angle for an OPG?
-8 degrees
Therefore things located closer to the x-ray beam are projected higher up on the final image relative to structures further away from source of radiation
What are the indications for panoramic radiography in dentistry?
“General dental screening” - OPGs are NOT accurate for caries assessment
- Impacted third molars
- Periodontal screening (periodontal bone loss)
- Mixed dentition & Eruption pattern of permanent teeth
- Orthodontics - Crowding, impacted canines, etc.
- Dental anomalies
- Jaw Pathology - Inflammatory lesions, odontogenic tumours & cysts, etc.
- Trauma (esp. mandibular fracture)
- TM Joints (not accurate L)
What are the medicolegal resposibilities?
True or Fale: All dental images must have radiology reports?
TRUE
Describe systematic approach to reading OPGs
