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what is the function of the silver halide crystals in the film emulsion?
absorb x-radiation and store the energy from the radiation to produce a pattern or latent image
how does the latent image become a visible image?
under special dark room conditions, a chemical reaction takes place when a film with a latent image is immersed in a series of special chemical solutions.
during processing, the halide portion of the exposed energized silver halide crystals is removed and leaves behind black metallic silver
during processing, the reduction of the energized silver halide crystals into black metallic silver, while the unenergized, unexposed silver halide crystals are removed from the film
what happens to the film as it goes through the developer solution?
- it distinguishes between the exposed and unexposed silver halide crystals
- reduction occurs
- unexposed silver halide crystals are unaffected
why do you rinse the film after it goes through the developer?
to remove any excess developer on the film
what happens to the film as it goes through the fixer solution?
- removes the unexposed silver halide crystals and creates white or clear areas
- black metallic silver remains intact
- rinsed and dried
describe the visible image of the radiograph
made up of black, grey, and white areas
structures that readily permit the passage of the x-ray beam and allow more x-rays to reach the film.
describe the process of radiolucent appearing on a film
x-rays reach film - silver halide crystals exposed - reduction to metallic silver on film=black areas on film
structures that resist the passage of the x-ray beam and restrict or limit the amount of x-ray that reach the film
describe the process of radiopaque appearing on the film.
x-rays do not reach the film - unexposed silver halide crstals are removed during processing=white areas on film
what are the 5 steps in film processing?
what is the purpose of the developer chemical?
to chemically reduce the exposed, energized silver halide crystals into black metallic silver
what is the purpose of rinsing after developer?
remove developer from film and stop the development process
what is the purpose of the fixer chemical?
remove the unexposed unenergized silver halide crystals from the film emulsion
what is the purpose for washing after removing the film from the fixer solution?
to remove all excess chemicals from the emulsion
what is the purpose of the final step, drying the films?
films must be dried before they can be handled for mounting and viewing
what are the 3 forms that the film processing solutions may be obtained in?
- ready to use liquid
- liquid concentrate
what must you mix with powder and liquid concentrate before use?
How do you keep your chemicals for film processing fresh?
- replenish them daily
- change every 3-4 weeks
- change more if exceeding 30 intraoral films per day
what are the 4 basic ingredients in the developer solution?
- developing agent
what are the 2 chemicals in the developing (reducing) agent? And what are their functions?
- hydroquinone - generates the black tones and sharp contrast
- Elon (metol) - acts quickly to produce a visible radiographic image, produces many shades of grey
why is the temperature of the developing solution so critical?
because hydroquinone is temperature sensative; it is inactive below 60*F and very active above 80*F.
what is the optimal temperature for the developer solution?
is elon temperature sensative?
how would the film appear if only elon was used in the developer solution? if only hydroquinone was used?
- gray indistinct contrast
- black and white
what chemical is used in the preservative chemical of the developer? What is it's function?
- sodium sulfite (antioxidant)
- to prevent the developer solution from oxidizing in the presence of air becaus hydroquinone and elon are sensative to oxygen
what chemical is used as the accelerator in the developer solution? And what is it's function?
- sodium carbonate (alkali)
- developing agents are active only in an alkaline (high ph) environment, it also softens the gelatin of the film emulsion so the developing agents can reach the silver halide crystals effectively
what type of chemical is used as the restrainer in the developer solution? And what is its purpose?
- potassium bromide
- controls the developer and to prevent it from developing the exposed and unexposed silver halide crystals, it prevents the image from appearing fogged
what are the 4 basic solutions contained in the fixer solution?
- fixing agent
- hardening agent
what chemical is the fixing agent in the fixer solution? And what is its purpose?
- sodium thiosulfate or ammonium thiosulfate
- to remove or clear all unexposed and undeveloped silver halide crystals from the film emulsion. It allows the black image produced by the developed to become distinguished
what chemical is used for the preservative in the fixer solution? What is it's purpose?
- sodium solfite
- prevents chemical deterioration of fixing agent
what is used for the hardening agent in the fixer solution? what is its purpose?
- potassium alum
- it hardens and shrinkds the gelatin in the film emulsion after it has been softened by the accelerator in the developer solution
what is the acidifier in the fixer solution? What is its purpose?
- acetic acid or sulfuric acid
- neutralizes the alkaline developer and is required by the fixer, if not then the unexposed crystals could continue to develop in the fixer
what is the primary function of the darkroom?
to provide a completely darkened environment in which x-ray film can be handled and processed to produce diagnostic radiographs
what is the ideal location and size of the dark room?
- located near area where x-ray units are installed
- large enough to accomodate equipment and work space, about 16 t0 20 square feet
what is the size of the dark room determined by?
- volume of radiographs processed
- number of persons using the room
- type of equipment used
- space required for duplication and film storage
what type of bulb is used for the safe light?
low-wattage bulb (7 1/2 or 15 watts)
removes the short wave lenghts in the blue-green portion of spectrum of visible light (damaging to film), permits the passage of light in the red-orange range;
what is an adequate safe light illumination distance, and time close to safe light for the film? what happens if these conditions aren't followed?
- minimum of 4 feet
- 2-3 minutes
- film fog
what are the requirements for the darkroom work space?
- adequate counter space
- clean, organized (to prevent artifacts and preserve quality)
what are the requirements for the darkroom storage space?
- unopened film boxes should not be stored in the dark room
- extraoral film must be stored in the dark room in light tight drawer
what are the requirements for the humidity level in the dark room?
- temperature of about 70*F is recommended
- film fog occurs if the temp is above 90*F
- 50-70% humidity is ideal
what happens if the humidity in the dark room is too high? or too low?
- high=film emulsion will not dry
- low=static electricity becomes a problem, and causes film artifacts
what are the requirements for the dark room plumbing?
includes hot and cold water for tanks and washing
what is the processing tank composed of?
- divided into compartments to hold the developer solution, water bath, and fixer soluton
- two insert tanks
- one master tank
true or false. The manual processing tank should be made of stainless steal and have a light tight lid.
2 removable insert tanks to hold the developer and the fixer solution, placed inside the master tank.
suspends both insert tanks and is filled with circulating water which controls the temperature and keeps it at the optimum temp of 68*F
controls water temperature in manual processor
What are some equipment accesories needed in using the manual processor?
- film hangers
- stirring rod or paddle
where must the thermometer be placed in the processor?
directly in the developer solution
what happens if the temperature is too cold, below 60? What happens if the chemicals are too hot, above 80?
- cold=chemicals work slow and result in underdevelopment
- hot=chemicals work too fast and result in film fog
development________________depends on the temperature of the development
temp= 68*; time ?
temp= 80*; time?
- 5 min in developer, 10 min in fixer
- 2.5 min in developer, 5-6 min in fixer
used to agitate the developer and fixer solutions prior to use
describe the step-by-step procedure for film processing
- determine solutions
- check solution levels, add solution if necessary
- stir solutions to mix and equalize temperature
- check developer temperature
- label film hanger with pt name and date
- close door, turn off white light, turn on safe light
- unwrap exposed film
- clip each film to the hanger
- set timer based on temperature
- immerse film hanger and aggitate to prevent air bubbles
- activate timer and cover tank
- rinse for 20-30 seconds
- determine fixing time (double the developing time)
- immerse in fixer; activate time and cover
- place films in water for 20 minutes
- dry films in dust free air or heated drying cabinet
what happens to the processing solutions if you don't take care of them?
they deteriorate iwht exposure to air, evaporation, continued use, and chemical contaminates
how should you care for the developer solution? What happens if you don't?
- add 6 oz to solution daily to replenish strength
- reduced density and contrast
how should you care for the fixer solution? what happens if you don't?
- add 3 oz of fixer solution at the beginning of each day
- films turn a yellowish brown color, transmit less light, and lose diagnositc quality
what chemical is used to remove salts and carbonate deposits from the manual film processor?
name 4 reasons why autonomic processors are preferred over manual processors.
- less processing time is required (4-6 min vs 1 hr)
- time and temperature are automatically controlled
- less equipment is used
- less space is required
encases all of the component parts of the automatic processor
processor housing of the automatic processor
an opening on the outside of the processor housing that is used to insert unwrapped films into the automatic processor
film feed slot
a system of rollers used to move the film rapidly through the developer, fixer, water, and drying compartments. produces a wringing action that removes excess solution. gently agitates the solution causing uniformity of processing
roller film transporter
holds the developer solution in the automatic processor
what is the optimal temperature for the developer solution in the automatic processor? What does this result in?
- development occurs rapidly
is the developer solution the same in the manual and automatic processors?
holds the fixer solution in the automatic developer
describe the procedure of the film through the fixer solution in an automatic processor.
- moves to fixer from developer with out a rinsing step
- solution contains extra hardening agents
- film is rapidly cleared or fixed and then hardened
is the fixer solution the same in the automatic and manual processors?
holds the circulating water and washes films flollowing fixation in the automatic processor
holds heated air and is used to dry the wet film
used to maintain proper solution concentration and levels automatically in some automatic processers
replenisher pump, replenisher solutions
opening on the outside of the processor housing where the dry, processed radiograph emerges from the automatic processor
film recovery slot
describe the step by step process of automatic film processing
- close door, turn off wight lights, turn on safe light
- unwrap and prepare films
- insert each film into the film feed slot making sure not to overlap
- allow 4-6 minutes for automatic processing
- retrieve films from processor
How does running a cleaning film through the automatic processor help clean and maintain it?
it removes residual gelatin or dirt from rollers
What is the proper care and maintenance for the automatic processor rollers?
clean weekly by running under warm water and soaking for 10-20 mins
how often should you replenish the processing solutions in an automatic processor?
every 2-6 weeks
what are 3 reasons why we made need to make a duplicate film.
- when referring pts to a specialist
- for insurance claims
- for teaching purposes
describe the step by step procedure for duplicatin films
- place radiographs to be duplicated on the light screen of the film duplicator
- use organizers to arrange films and block out extra light
- place duplicating film on top of the radiographs (with emulsion side-dull and gray or lavender in color-down)
- secure duplicator
- select exposure time
- process duplicating film
in duplicating films, the longer the film is exposed to light, the_________________
lighter it appears
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