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What is the most common image receptor?
Photosensitive film
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Photosensitive
sensitive to electromagnetic energies
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4 components of modern x-ray film
Base, Emulsion, adhesive, and supercoat
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What layer is flexible, durable and contains blue dye?
base
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What layer is made of silver halide crystals in gelatin?
Emulsion
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What layer holds emulsion to base?
adhesive
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What layer prevents bubbling of emulsion during processing?
adhesive
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What is the protective coating to prevent damage to emulsion?
supercoat
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What are the 4 factors of film?
Resolution, contrast, speed, latitude
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resolution
ability to show detail
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Higher resolution has smaller or larger crystals? Thinner or thicker layers?
smaller crystals and thinner layers
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Contrast
Amount of gray shades imaged by a type of film
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Higher resolution will result in lower or higher contrast?
higher contrast
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speed
Sensitivity to light and ability to creat image
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latitude
films ability to image various densities and contrasts
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What yields wider latitude?
Larger crystals with thicker layers
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Wider latitude is good for chest or knee xrays?
chest x-rays
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latent image
unseen change in film before processing
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What ionizes to produce the latent image?
Silver halide crystals by light photons from screen
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T or F Greater than 99% of latent image is formed by x-ray photons
false
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T or F Less than 1% of latent image is formed by visible light from intensifying screens
false
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What action begins the manifest image process?
Inserting the film into the processor
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What are the 5 types of film?
Intensifying screen, direct exposure, detail extremity, single emulsion, duplication
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What film uses large amts of silver in a thick layer?
Direct exposure
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What film is used for bone work?
detail extremity
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What film is used for mammography and ultrasound?
single emulsion
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What film requires small crystals, higher dosages, and no grid?
detail extremity
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What T should films be stored at?
<68 degrees
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How long are films kept for?
7 years, longer for minors
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How long are N.A.T. films kept for?
20 years
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What is the standard procedure for manual processing?
time/T method
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What is the Time/T method
Developer is 5 min. @ 68 degrees
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If T increases in manual processing, developing time?
Decreases (hotter- faster)
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What are the 4 stages of processing?
Developer, fixer, wash, and dry
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What chemical is used in the fixer stage
acid chemical
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What chemical is used in the developer stage?
Base chemical
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What is used in the wash stage
water
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What is used in the dry stage?
heat
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Does automatic processing occur at a higher T than manual?
yes
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In automatic processing, what are the times for each stage?
Developer, 20-25s; Fixer, 20s; Wash, 20s; Dry, 25-30s
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transport rocks
system of rollers
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crossovers
direct film from one chemical tank to next
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Drive System
Gears and chains of belts which drive mechanism
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Replenishment
chemicals are constantly refreshed as they are used to maintain consistency
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What stage is most sensitive to contamination?
developer
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Silver recovery is mostly recovered from?
fixer
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What is the least expensive method of silver recovery?
overflow
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Undeveloped green film contains much?
silver
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What overflow is toxic in silver recovery?
fixer
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chemical fog
unwanted exposure of film by environment
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What are the 3 causes of chem. fog?
Developer T is too high, Developer time is too long, [ ] of chemicals is too strong
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If developer T is too cool what will happen to the film?
under developed
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T or F Film is more sensitive to exposure after it has been exposed?
true
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Safeness of environment is controlled by what 3 factors?
Wattage, type of filter, and distance
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The wattage of the bulb should be?
7-15watts
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What is the standard filter in x-ray?
Kodak GBX dark red
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What is the distance from the work area?
4 feet
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sensitometry
science of measuring film/processing response and comparing to specifications of manufacturer.
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What is the least accurate sensitometry method?
penetrometer
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What is used to read optical density in designated sections of the film?
densitometer
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Good sensitometry should be done at what part of day?
Same time of day at regular intervals
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What is used to determine normal limits in sensitometry?
D log/E curve (Hurter and Driffield Curves)
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Unexposed silver halides are washed away in what stage?
fixer stage
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Silver is mostly recovered in what stage?
Fixer stage
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What are th 4 methods of silver recovery?
Metallic replacement, electrolytic, chemical precipitation, and resin
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Can scrap film be recycled?
yes
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What screen changes photon energy into visible light?
Intensifying screens
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Is pt. exposure reduced with intensifying screens?
yes
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Screens are constructed of what 4 parts?
Base, reflective layer, phosphor, and protective coating
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What screen layer directs isotropic light toward film?
Reflective layer
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What screen layer emits light when excited by x-ray photons?
phosphor
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Luminescence
ability of a material to emit light when excited
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What are the 2 types of luminescence?
Phosphorescence and Fluorescence
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What luminescence type has instantaneous emission
Fluorescence
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What luminescence type is bad?
Phosphorescence
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Spectral matching
matching light color with sensitivity of film
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Calcium tungstate emits what color of light?
blue
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Rare Earth emits what color of light?
yellow-green
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Rare Earth uses phosphors with Atomic #?
57-71
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Does calcium tungstate or rare earth reduces pt. exposure?
Rare earth
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Does intensifying screens have the same characteristics as film?
Yes, resolution, speed, and contrast
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Poor contact results in loss of what?
Loss of image sharpness and increased density at the area of poor contact
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Artifacts
Unwanted densities that obscure film details
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Higher speed screens require less or more exposure to produce an image?
less exposure
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Are higher or lower speed screens used for larger body parts?
Higher speed screens
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Relative speed and what are inversely related?
mAs
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What is the relative speed formula?
mAs1/ mAs2= RS2/RS1
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