Film Processing Flashcards
What is film processing?
Steps that produce a visible image on a dental radiograph
- convert the latent image to a visible image
- preserve the image so it is permanent
What are film processing fundamentals? (simple step by step)
- silver halide crystals: absorb x-radiation during x-ray exposure
- latent image: the pattern of stored energy on exposed film
- from latent image to visible image
- the visible image
What is reduction?
A chemical reaction where the halide portion of the exposed, energized silver halide crystal is removed. Reaction results in precipitated black metallic silver
What is selective reduction?
Reduction of energized, exposed silver halide crystals into black metallic silver while the unenergized, unexposed silver halide crystals are removed from the film
Describe the process of a film going from latent image to visible image
- the film is placed in a developer solution (proper temperature and time, creates black metallic silver, dark areas on plastic film)
- the film is rinsed in water
- the film is placed in a fixer solution that removes unexposed silver halide crystals leaving clear or white areas on the plastic film
- the film is washed in water
What ‘colours’ are shown on the visible image?
Black, white and grey areas
What does the amount of black areas in the visible image depend on?
the amount of black metallic silver depending on the structures being x-rayed (radiolucent vs radiopaque)
What is radiolucency? Radiopaque?
Radiolucent means readily permits passage of x-rays and will result in a dark area. Radiopaque means resists the passage of the x-ray beam and will appear white
What are the 5 steps for film processing?
- development
- rinsing
- fixation
- washing
- drying
Describe the process of development
reduces the exposed, energized silver halide crystals into black, metallic silver. softens the film emulsion
Describe the process of rinsing
stops the development process and is necessary to remove the developer from the film
Describe the fixing process
removes the unexposed, unenergized silver halide crystals from the film. hardens the film emulsion
Describe the washing process
removes all excess chemicals from the emulsion
why do we do the drying process?
films must be dried before they can be handled for mounting or viewing
What forms can film processing solutions come in?
- powder
- ready-to-use liquid (most common)
- liquid concentrate
How can we maintain freshness of film processing solutions?
- must be replenished daily
- must be changed every 3 to 4 weeks
- may needs to change more frequently when large numbers of films are being processed
What 2 chemicals can we find in the developer solution? What do these chemicals do?
- hydroquinone: generates black tones and the contrast on the film (temperature sensitive 68 Fahrenheit optimal temp)
- elon: produces the shades of gray on the radiograph (combination of these chemicals produce black, white and gray shades)
What does the preservative in the developer solution do?
prevents developer solution from oxidizing in the presence of air. sodium sulfite-agents
What does the accelerator do in the developer solution?
softens gelatin of film emulsion. sodium carbonate-activates
What does the restrainer in the developer solution do?
prevents development of unexposed crystals. potassium bromide
What can we find in the fixer solution? What do these do?
- fixing agent: removes or clears all unexposed/undeveloped crystals so black image is visible
- preservative: prevents deterioration of fixing agent
- hardening agent: hardens gelatin emulsion
- acidifier: neutralizes alkaline developer and prevents further developing
What is a darkroom?
A completely darkened environment within which x-ray film can be handled and processed to produce diagnostic radiographs
What are the 5 requirements of a dark room?
- conveniently located
- adequate size
- equipped with correct lighting
- arranged with ample work space and adequate storage
- temperature and humidity controlled
Location and size of darkroom
- should be near where x-rays are installed
- large enough to accommodate film processing equipment and allow ample work space