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
What is the size of the darkroom determined by?
- volume of radiographs
- number of persons using the room
- type of processing equipment (automatic vs processing tanks)
- space required for duplication of films
- storage
What kind of lighting must be present in a darkroom?
Must be light-tight (no light leaks can be present), though we can have ‘safe lighting’ which is long wavelengths in the red-orange portion of the visible light spectrum that provides illumination during film processing
What will occur if we have a light leak in the dark room?
Any leaks of white light in the darkroom can cause ‘film fog’ and results in an undiagnostic image
Safelight
- a lamp with a low-wattage bulb (15 watts or less)
- safelight filter removes short wavelengths in the blue-green portion of the visible light spectrum
- a safelight should be placed a minimum of 4 feet away from the film and working area
- films must be processed immediately
What equipment is required in the darkroom for processing images?
- processing tank
- insert tanks
- master tank
- mixing valve
What is the processing tank?
Found in the darkroom, divided into 2 compartments to hold developer solution, water bath, and fixer solution
What are the insert tanks?
- two tanks to hold developer and fixer solutions, both fit into the master tank
What is the master tank?
- suspends both insert tanks
- filled with circulating water
What is a mixing valve?
- controls the water temperature
What equipment accessories are needed for developing x-ray images?
- thermometer (placed in developer solution)
- timer (to indicate processing time intervals)
- film hangers
- miscellaneous equipment (stirring rod)
Step-by-step procedures for film development
- identify the solutions
- check solution levels
- stir the solutions
- check temperature of developer solution
- label film hanger
- prepare the darkroom
- unwrap the films
- load the hanger
- set the timer
- immerse the films and begin timing
- remove the films from the developer, and rinse
- determine fix time
- immerse the films and start the timer again
- remove the films from the fixer and place into the water wash
- dry the films
- remove the films from the rack
- clean up
How to care for the processing solutions
- follow manufacturer’s instructions for storage, mixing and use
- developer solution (ensure it is full and not exhausted)
- fixer
- replenisher solution (both developer and fixer must be replenished daily)
- replenisher (super concentrated solution)
- oxidation (the process that occurs when developer and fixer combine with oxygen and lose strength)
What can cause deterioration of processing solutions?
- exposure to air
- continued use
- chemical contamination
How can we care for the fixer solution?
depletes from evaporation and removal of small amounts. dilutes each time water is transferred from rinse. exhausted fixer does not stop the chemical reaction sufficiently
Why do we need to clean the processing tank? How can we clean it?
Mineral salts in water and carbonate in processing solutions produce deposits on the inside walls of the insert tanks. Tanks must be cleaned with commercial cleaner or hydrochloric acid when the solutions are changed
What are some miscellaneous pieces of equipment for developing images?
- film hangers
- stirring paddles
- plastic apron
What is automatic film processing? Where can we use them?
- automates all film-processing steps
- some may be limited to certain sizes of films
- some may require a darkroom
- some have a daylight loader and may be used in a room with white light
What are the benefits of automatic film processing?
often preferred over manual processing because:
- less processing time requires (4-6 mins)
- time and temperature are automatically controlled
- less equipment used
- less space required
- produces high quality radiographs and provides less chance for operator errors
What equipment is required for the automatic film processing?
1 - processor housing (covers processor)
2 - film feed slot (opening to insert unwrapped film)
3 - roller film transporter (moves film and has wringing action to remove excess solution and eliminated need for rinsing)
4 - developer compartment (different solution than manual, designed to react to temp 80-95 degrees so it’s faster)
5 - fixer compartment
How does the automatic film processing work?
uses a roller transport system to move unwrapped dental x-ray film through the developer, fixer, water and drying compartments
What steps does the automatic film processor do for you in the fixer compartment?
- water compartment (washes films)
- drying chamber (heated air)
- some have replenisher pump and replenisher solutions)
- film recovery slot (opening where film emerges)
What step-by-step procedures must we complete for the automatic film processor?
- prepare the darkroom (if no daylight required)
- prepare the films
- insert each unwrapped film into the film feed slot of the processor (careful with time and slots; allow time between insertion of each film and try to use different slots to prevent the overlapping of films)
- process and retrieve the films
Care and maintenance of the automatic processor
- requires routine preventive maintenance (a cleaning and replenishment schedule must be established to ensure optimum performance, may require daily or weekly cleaning)
- cleaning film (used to clean the rollers of an automatic processor with an extraoral film, removes any residual gelatin or debris on rollers)
- rollers must be removed and cleaned every week
Care and maintenance of the processing solutions in the automatic film processors
- levels must be checked at the beginning of each day and replenished as necessary
- to keep solutions fresh and strong to produce a high quality radiograph
- failure to add replenisher solution results in exhausted solutions and non diagnostic radiographs
What is the use of a film duplicator?
an identical copy of an intra or extraoral radiograph is made through the process of film duplication. duplicate radiographs may be used when referring to specialists, for insurance claims and as teaching aids
What equipment is necessary for duplicating radiographs?
- film duplicator (commercially available light source)
- duplicating film
Step-by-step procedures for duplicating film
- arrange the radiographs in anatomic order
- place duplicating film on top of the arranged radiographs emulsion side down
- secure duplicator lid to ensure proper contact between radiograph and duplicating film
- select exposure time and activate light source
- process the duplicating film
- label the processed duplicate radiographs
What can cause processing problems in developing film?
- time and temperature errors
- chemical contamination
- improper film handling
- lighting
What could happen to cause an underdeveloped film?
- inadequate development time
- developer solution too cool
- inaccurate timer or thermometer
- depleted or contaminated developer solution
What could happen to cause an overdeveloped film?
- excessive developing time
- developer solution too hot
- inaccurate timer or thermometer
- concentrated developer solution
What happens when there is a sudden change in temperature between developer and water bath?
Reticulation of emulsion
What can cause developer spots?
when the film comes in contact with developer before being placed into the developer bath
What can cause fixer spots?
when the film comes into contact with fixer solution before entering the fixer bath
What can cause yellow-brown stains on a film?
- insufficient rinsing
- developer is old
- fixer is old
- caught in developer (insufficient fixer time)
What errors can we cause in the film from the developer and fixer?
If the solutions aren’t high enough, you will see a cut off in the images
What do air bubbles look like in film?
tiny dots
What can cause overlapped films? What do they look like?
- common in automatic
- films put into developer too quickly
- looks like another film on top of the image
What can happen from film handling? What can cause these?
- fingernail artifacts (caused by aggressive opening of film packets)
- fingerprint artifacts (caused by developer or fluoride on a finger in manual, in auto if handling occurs before film is completely fixed)
- static electricity (caused by removing film too quickly in a carpeted office, not common anymore, looks like little lightning bolt in image)
- scratched film
- light leak (looks darker in one area)
- fogged film (caused by small light leak, old film, contaminated solutions or high developer temp)
