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18 Cards in this Set
- Front
- Back
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Describe in detail how a latent image becomes a visible image
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Silver halide crystals in film emulsion:
-absorb radiation during exposure and stores the energy from radiation -stored energy within the crystals form a pattern, creates an invisible image -pattern of stored energy on the exposed film is a latent image A chemical reaction occurs: -the halide portion of the exposed, energized silver halide crystal is removed (Reduction) -REDUCTION results in the crystals becoming totally black while the unexposed (unenergized) silver halide crystals are removed from film (SELECTIVE REDUCTION) -Latent image is mad thru chemical processing |
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List and discuss the five steps of manual film processing
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1) Developement
2) Rinsing 3) Fixation 4) Washing 5) Drying 1) Development (reduction occurs) -to reduce the exposed, energized silver halide crystals into black, metallic silver -softens the film emulsion: emulsion has a protective layer. must soften so emulsion can dissolve and process 2) Rinsing -STOPS the development process -remove the developer from the film 3) Fixation (Selective Reduction) -Removes the unexposed, unenergized silver halide crystals from the film -hardens the film emulsion 4) Washing -Removes all excess chemicals from the emulsion -stop the fixation 5) Drying -Films must be dried before they can be handled for mounting or viewing |
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List and describe the four basic ingredients of the developer solution
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1) Developing agent (reducing element)
-contains 2 chemicals: =hydroquinone: generates black tones and sharp contrast =Elon: generates shades of gray 2) Preservative - sodium sulfite 3) Accelerator - sodium carbonate 4) Restrainer - potassium bromide -optimal temp for solution = 68 degrees for hand processing |
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List and describe the four basic ingredients of the fixer solution
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1) Fixing agent (clearing agent)
-Sodium thiosulfate or ammonium thiosulfate 2) Preservative - sodium sulfite 3) Hardening agent - potassium alum 4) Acidifier - acetic acid or sulfuric acid |
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Safelighting
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-long wavelengths in the red-orange portion of the visible light spectrum
-a lamp with a low-wattage bulb =7.5 or 15 watt -safelight filter =Removes short wavelengths in the blue-green portion of the visible light spectrum -safelight paced a min of 4 feet away from the film and working area |
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Discuss the parts of the processing tank: insert tanks, master tank, and lid
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Manual processing:
-Processing tank: =divided into compartments to hold developer solution, water bath, and fixer solution -Insert tanks: 2 tanks -developer and fixer solutions -both fit into master tank Master tank: -Houses both insert tanks -filled with circulating water -mixing valve: controls water temp |
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List and describe the equipment needed for manual film processing
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Thermometer: placed in developer solution
Timer: to indicate processing time intervals Film hangers |
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List and discuss the procedural steps for manual film processing
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-Identify solutions and check levels (developer, water, fixer)
-stir solutions -check temp of developer (determines time) Lower temp = longer processing time -Label film hanger with name of pt and date of exposure -Close and lock darkroom door, turn off white lights, and turn off safelight -unwrap each exposed intraoral film over clean working surface -clip each film to the labeled film hanger -immerse into developer solution, agitate (timed) -Remove films from developer, place in circulating water -immerse the film in fixer solution, agitate (timed) -Remove films from fixer, place into circulating water -Remove films from circulating water -air dry films -remove the radiographs from the film hanger -examine radiographs -mount -clean processing equipment and work surfaces |
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Describe the care and maintenance of the processing solutions, equipment, and equipment accessories used in manual film processing
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Processing solutions:
-Follow manufacturer's instructions for storage, mixing and use -solutions deteriorate with: exposed air, continued use, chemical contamination Developer solution: -Depleted from evaporation and removal of small amounts -Exhausted developer does not fully develop the latent image Fixer solution: -Depleted from evaporation and removal of small amounts -diluted each time water is transferred from rinse -exhausted fixer does not stop the chemical reaction sufficiently Replenisher solution: -both developer and fixer must be replenished daily Replenisher: -superconcentrated solution Oxidation: -occurs when developer and fixer combine with oxygen and lose strength Processing tank: -Deposit build up on inside walls of insert tanks (from mineral salts in water and carbonate in processing solutions) -tanks must be cleaned with commercial cleaner or hydrochloric acid when the solutions are changed -rollers are cleaned from automatic processors |
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Discuss the advantages of automatic film processing
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-Less processing time
-time and temp automatically controlled -less equipment used -less spaced required |
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List and identify the component parts of the automatic film processor
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-Processor housing
-film feed slot -roller film transporter -developer compartment -fixer compartment -water compartment -drying chamber -replenisher pump and solutions -film recovery slot |
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Describe the mechanism of automatic film processing
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Uses a roller transport system to move dental x-ray film through developer, fixer, water, and drying compartments
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List and discuss the four procedural steps for automatic film processing
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1) Prepare darkroom
2) Prepare films 3) Insert each unwrapped film into the film feed slot of the processor 4) Retrieve the processed radiographs |
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Describe the care and maintenance of the automatic film processor and automatic processing solutions
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-Requires routine preventive maintenance
=a cleaning and replenishment schedule must be established =may require daily or weekly cleaning -"cleaning" film: used to clean the rollers of an automatic processor -Processing solutions =levels must be checked at the beginning of each day and replenished as necessary |
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Describe film processing problems that result from time and temperature errors
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Underdeveloped film:
-The film appears light -Too little time in the development -temp too cold -depleted or diluted solution Overdeveloped film: -dark film -too much time in developer -temp too warm -solution too concentrated Reticulation of emulsion: -film looks cracked -drastic temp change b/w developer solution and water bath |
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Describe film processing problems that result from chemical contamination errors
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Developer spots- dark spots on film
fixer spots - white spots on film yellow/brown stains - insufficient time in fixer or water |
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Describe film processing problems that result from film handling errors
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Developer cut-off:
-Straight white border appears on film (low levels of developer solution) Fixer cut-off: -straight black border appears on film (low levels of fixer solution) Overlapped films: -white or dark areas appear on films where overlap occurred Airbubbles: White spots appear on film Fingernail artifact: -Black, crescent-shaped marks on film Fingerprint artifact: -Black fingerprint on film Scratched film: White lines on film Static electricity: Thin, black branching lines on film |
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Describe film processing problems that result from lighting errors
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Light leak - black film
fogged film - lacks image detail and contrast (appears gray) from developing |
