Module 5 Flashcards
What are the 3 sizes of intraoral film packets?
22 x 35 mm - anterior PA and children BW
31 x 41 mm - posterior PA and adult BW
57 x 76 mm - occlusal
What are the 2 types of radiographic films?
Direct and Indirect action films
What is the difference between direct and indirect action films?
Direct = non-screen, wrapped or packet films.
Indirect = used with intensifying screen inside an extra-oral cassette.
What colour is the surface of the film packet facing the X-ray beam?
What colour is the reverse surface?
White.
White + another colour.
What speeds of films are available?
D, E, F
F = fastest
How can you tell the difference between the different speeds of films?
Different colours.
(problems due to different manufacturers having different colours).
What are the contents of a film packet?
- Clear plastic barrier envelope.
- Outer plastic wrapper (white and colour coded).
- Plastic film with an embossed dot on one corner.
- Black paper on either side of the film.
- Thin sheet of lead foil.
What is the purpose of the embossed dot on the corner?
For orientation.
- Always place TOWARDS the X-ray beam.
What is the purpose of the black paper on either side of the film?
Protection from mechanical damage from fingers (when handling/unwrapping), light and saliva.
What is the purpose of the lead foil in the film packet?
Prevent secondary scatter degrading the image.
Prevent residual radiation continuing into patient’s tissues.
What’s the purpose of gelatin in the film?
Protect emulsion from mechanical damage.
What’s the purpose of adhesive in the film?
Fix emulsion to the base.
What is the emulsion made of?
Silver halide.
What is the emulsion sensitive to?
Primarily = X-ray photons (also light) - open in dark.
What happens if the film packet is placed the wrong way round in the patient?
Embossed pattern shows on the film and results in a pale image.
