Exposures - Procedures, Calculations, & Legislation Flashcards
Describe the different layers of X-Ray film
Super coat - protects layers of emulsion
Emulsion - suspension of sliver halide (silver bromide) crystals in gelatine
Subbing layer - adhesive layer
Polyester base - provides support
What are the 3 different types of x-ray film?
Orthochromatic screen film - used with green and blue light emitting rare earth intensifying screen.
Monochromatic screen film - used with calcium tungstate blue light emitting rare earth intensifying screens.
Single-sided emulsion layer - used in cassettes with single screens, good for finer detail.
What sort of film is commonly used for dentistry?
Non-screen film
What can affect the quality of the x-ray when using a non-screen film?
If the flexi cassettes are used due to poor film screen contact and the high mAs required.
A faster film speed results in……
low definition image.
larger particles within the emulsion layer and intensifying screens inside a cassette.
A slower film speed results in…….
high definition image.
small particles
A medium film speed results in……….
a good quality image, most used in practice
How should film be stored?
- away from direct sunlight
- away from sources of radiation
- away from fumes
Define: radiolucent
allows radiation to pass through it
Define: radiopaque
prevents radiation passing through it
What are some key features of a cassette?
- light-proof box, holds intensifying screen against x-ray film
- top = radiolucent
- back = has a lead lining to absorb scatter
What is the purpose of an intensifying screen?
included in the x-ray cassette to reduce exposure time
What light is produced by phosphors then exposed to X-rays - calcium tungstate screens?
blue light
What light is produced by phosphors when exposed to x-rays - rare earth screens?
blue-green light
Suggest ways that you should take care of cassettes.
- keep Clean (dust and hair can lead to misdiagnosis)
- disinfect after each use (be aware of chemicals used)
- check hinges and locks after every use
- handle with care (pricey)
- keep cassettes loaded with film at all times
