Film and Screens Flashcards
(21 cards)
What are the 3 basic components of film?
Base, overcoat, and emulsion
What is the base made of and what is its purpose?
Made of plastic, supports the emulsion
What is the overcoat made of and what is its purpose?
Made of a non-abrasive gelatin and rptects the emulsion from mechanical damage
The purpose of the emulsion is?
Recording
What is the emulsion sensitive to?
x-rays and light
Why is emulsion double coated?
To increase sensitivity and allow us to use a lower dose
What is the emulsion made of?
A homogenous mixture of pure gelatin and silver halide grains
What is used to make the silver halide more sensitive?
Gold or sulfur
The silver halide crystals are made of?
95% silver bromide and 5% silver iodide
The shape and size of the silver grains determines?
The characteristics of the film
How should the crystals be oriented to catch the maximum amount of rays?
Parallel to the film surface
Intraoral film is known as?
Direct exposure film
What is the advantage and disadvantage to intraoral or direct exposure film?
Very sharp images but need a higher dose than indirect
How many sizes does intraoral film come in and what are each of them used for?
5 sizes
0-1 for children
2 for standard periapical/bite wing
3 for extended bite wing
4 for occlusal film
What is the advantage to higher speed film?
More sensitive and requires lower radiation dosage
Extra oral film is AKA?
Screen film
What is often used with extra oral film?
An intensifying screen
What kind of X-rays is extra oral film used for?
Panoramic, lateral and postero-antero cephalometrix, skull x-rays
What is the point of the lead foil backing?
Attenuate the beam and absorbs scattered radiation so it doesn’t strike the emulsion a second time from behind
If the film is reversed what will appear?
Tire track and low density
What is the intensifying screen?
A layer of phosphor, fluoresces when X-rays hit it
