Film Radiography Flashcards
What are the components of an intra-oral film packet?
Radiographic film
Protective black paper
Lead foil to absorb excess photons
Outer wrapper to prevent ingress of saliva
What is a radiographic film?
Material in which the actual image is formed
Sensitive to both x-ray photons and visible light photons
How is an image produced on a radiographic film?
Photons interact with emulsion on film to produce latent image which only becomes visible after chemical processing
What are the components of the radiographic film?
Transparent plastic base to support the emulsion
Adhesive attaches the emulsion to the plastic base
Emulsion layered on both sides of the plastic base
Protective coating of clear gelatin shields the emulsion from mechanical damage
What forms the radiographic emulsion?
Sliver halide crystals embedded in a gelatin binder
Crystals are microscopic and effectively become the pixels of the final image
What happens to the silver halide crystals?
Become sensitised upon interaction with x-ray and visible light photons
Sensitised crystals make dark parts of final image
Non-sensitised crystals make light parts of image
How does film speed affect the x-ray exposure required to produce an image?
Increased film speed decreases the radiation required to achieve an image
How and why are intensifying screens used?
Used alongside special indirect action film for extra oral radiographs to recude radiation dose
What are the different methods of film processing?
Manual
Automated
Self-developing films
What are common steps in film processing?
Developing
Washing
Fixing
Washing
Drying
Describe a manual or ‘wet’ cycle
Person dips film into different tanks of chemicals at precise concentrations/temperatures and for specific periods of time
Films are washed after each tank
Must be carried out in a dark-room
Describe an automated cycle
All necessary steps carried out within a machine
Exposed film goes in one end and processed film comes out the other
Faster than manual but more expensive
What are the advantages of self-developing films?
No darkroom or processing facilities required
Faster
What are the disadvantages of self-developing films?
Poorer image quality
Image deteriorates more rapidly over time
No lead foil
Easily bent
Difficult to use
Expensive
What are the potential causes of a pale image?
Exposure issue - radiation exposure factors too low
Developing issue - film removed from solution too early, solution too cold, solution too dilute/old
