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57 Cards in this Set
- Front
- Back
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film emulsion consists of silver halide grains that are both ________ and _______
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photosensitive and radiosensitive
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To creat distortion between the regular arrangement of the silver and bromide ions in the crystalline lattice, what is added
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large iodide ions
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what is another name for sensitivity sites
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Latent image sites
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how are the silver halide crystals made more sensitive
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addition of trace amounts of sulfur
NOTE sulfur compounds creat the sensitivity sites that contribute to latent image formation |
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What happens at the latent image site
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xrays knock an electron off bromide converting it to bromine. These electrons strick a latent image site and give it a negative charge which allows the site to attract free silver ions to itself
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What begins latent image formation
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Sensitivity sites
Each Ag Halide crystal has multiple sensitivity sites |
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During what process does the conversion of silver ions in the crystal to mettalic silver occur
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processing
the black metallic silver grains can be visualized after processing |
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What are the 2 types of processing
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Manual and Automatic
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Give the steps in both manual and automatic processing
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Manual - Wetting, Developing, Rinsing, Fixation, Washing Drying
Automatic - Developing, Fixation, Washing Drying |
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What is the optimal temp for manual processing
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68-70 deg F
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What is the primary function of developer
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conversion of silver halide into metallic silver atoms
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What is the primary reducing agent in the developer
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Phenidone - it is an electron donor(thus its oxidized), that converts the Ag ions into black metallic silver atoms at the latent image site
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What is the secondary reducing agent in the developer
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Hydroquinone - it reduces the oxidized form of Phenidone to its original reduced state so it can be ready for another cycle
Hydroquinon also helps build up contrast thru gray, black and white tones |
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What is the name of the alkali compound or activator in the developer
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Sodium or Potassium hydrozide
they help keep the pH around 10 and softens the gelatin for difussion of the developing agent. NOTE: Sodium Carbonate Acts as a buffer to maintain alkaline pH |
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What is the name of the preservative or antioxidant in the developing solution
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Sodium sulfite -
it prevents rapid oxidation of developing agent by O2, extends the life of dev agent and removes oxidation products that may interfere and stain the film |
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What is used as the restrainer in the developing agent
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Sodium Bromide(antifog agent) - it restrains the development of unexposed Ag halide crystals thus preventing fog
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What is the primary function of the fixing agent
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removal of unexposed or underdeveloped Ag halide crystals. Also hardens and shrinks the film emulsion
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What is the name of the fixing or clearing agent
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Ammonium Thiosulfate -
it removes unexposed Ag halide grains from film emulsion |
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What is the name of the acidifier in the Fixating solution
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Acetic Acid-
maintains pH around 4 to 4.5. It promotes difussion of ammonium thioslufate and removes silver thiosulfate out of the emulsion. Also blocks development of unexposed crystals |
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What is the name of the preservative in the fixating solution
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Sodium or Ammonium Sulfite -
keeps chemical balance, prevents oxidation of thiosulfate clearing agent, binds with any colored oxidized developer carried into the fixer and removes it and prevents oxidized developer from staining the film |
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Films turn brown after time if you what
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you use depleted solution or you didnt wash it properly
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What is the hardner compound in the fixation solution
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Aluminum Salts - reduces swelling of emulsion during final wash by limiting water absorption and drying times. Also prevenet damage to the gelatin during hardening
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What can result in darker radiographs(higher density)
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Prolonged development
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What can result in a gradual loss of film density
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Excessive fixation
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What does the washing process do below 60 deg F
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the efficiency declines rapidly
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What is washing done for
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to remove all residual processing chemicals(thiosulfate and Ag thiosulfate complexes) that may obscure the diagnostic info in the final image
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What is the reason for discoloration
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improper washing
Thiosulfate + Ag = Silver sulfide(brown) |
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What is the drying proess done for
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Removes moisture from the film and prepares it for viewing
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What can uneven drying lead to
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distortion of gelatin and thus variation in density may be seen
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What are some steps you need to take before starting manual processing
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- adequate safelight in room
- check solution levels - stir solution frequently - check solution temp. - unwrap exposed film package - load film on hangars - set interval timer - process your little ass off |
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Give the steps and times for the manual processing procedure
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wetting in develop(30 sec)
development (5 min at 68 F) water rinse(30 sec) Fixation (10 min) Washing(10-15 min) Drying(30 sec) |
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Why is auto processing better
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Shortens time to 1.5 to 6 min
rollers move films contrast end results less floor space daylight loading possible less required equipment wet reading of films is eliminated |
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What are the functions of the rollers
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move the film along the process, uniformity, prevents carry over contamination between solutions, and rolling motion stirs solutions for you
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What are the characteristics of the developer and fixer
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developer is alkaline and feels soapy
fixer is acidic and has a sharp smell |
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What are some chemicals that are added to the automatic developing solution
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Gluteraldehyde(hardener, might be active ingredient in Viagra)
Sulfate(minimize swelling) |
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What are some of the time/temp correlation of the time required to process automatically
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90 sec at 90-95 deg F
4.5 min at 83 deg F |
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What are some precautions to take when feeding films
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slowly and carefully,
dont feed wet/damp films, too rapidly or bent films |
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What does uneven drying cause
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distortion of the gelatin and spots on the film
Dry in no higher than 49 deg C and make sure its adequately ventilated |
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Why should you change film processing solutions every day even if you dont use them
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The air oxidizes the compounds - developer does this
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What can the use of exhausted developer result in
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slower development times and reduced density and contrast
Density - amount of blackness on film Contrast - differences in densities |
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What can use of exhausted fixer cause
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slower removal of unexposed crystalls and silver thiosulfate complexes which results in incomplete clearing and films turn brown with age
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What is a step wedge used for
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the check image quality when solutions are changed(its a reference film)
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when do you know its time to change solutions
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when you notice loss of density and contrast(you wont be able to see outlines of your step-wedge)
NOTE change both solutions at the same time |
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What are rapid processing chemicals and what are they used for
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they are more concentrated and work in about 15 sec develop and 15 sec fixation. Typically used for emergency or endo situations.
HOWEVER they are not recommended cause they can become discolored over time and provide lower film contrast |
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how can you improve the rapid processing chemical films
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regular fixation for 4 min and washing for 10 after view will improve contrast and storage
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What are some things that should be done to the automatic processor maintenance wise
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inspect rollers for allignment
lube moving parts monthly solution replenishment every 15-30 days (KEEP A LOG) open cover at end of day to let air out |
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what things should you look for in a safelight in your processing room
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Color of filter, distance and wattage, and safelight exposure time
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What are the recommended safe lights
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Kodak ML-2(yellow/orange color) - its used with intraoral D(ultraspeed) film only cause it can fog extraoral and F speed film
Kodak GBX(ruby red color) - safe with all extraoral and intraoral films thus its called the universal filter |
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What are the recommended distances and wattage for your safelight
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15 watts and min 4 feet
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how do you test the safelight in your darkroom
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unwrap film and place a penny on it, leave the film on the workbench for you amount of time it takes to open a packet and feed it into processor. Then process the film, if penny is visible then your safelight sucks ass get a new one!!!!!
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What are the 2 primary ingredients of radiographic waste management
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disolved silver in used fixer which is disposed by electroplating
lead foil in film packets which should be sold to scrap metal dealer MAKE SURE THE COMPANIES ARE LICENSED TO DO THESE PROCESSES |
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what is the process to mount and view the film
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raised dot towards the viewer, dot is always toward the occlusal surface, use magnifying glass and block all extraneuous light
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Give some examples of where the dot should be
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in PA film it is always towards the occlusal surface of the teeth
BUT in occlussal the dot is towards the lower edge in BITEWING FILMS at OUCOD |
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What are the reasons for mounting dental radiographs
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less chance of error in interpretation, prevention of finger marks, scratches and abrasions. Easy to file and review. Educational value to the patient
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Film duplication procedure
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Direct reversal film- solarized by light or checmical treatment of emulsion
More light exposure produces less density The side of the film with emulsion is purple --- only 1 side has emulsion on this type of film |
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What is on the side opposite the emulsion side on a Film Duplication procedure
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antihalation coating - it absorbs the reflected light before it reaches the emulsion again
IT REDUCES UNSHARPNESS |
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Where is the film duplication procedure done
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in the darkroom, using an ultraviolet light source.
the original radiograph and duplicating film placed in close contact with emulsion side Greater the exposure time lighter the film KODAK X-Omat duplicating film |
