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heather.dundas
on FreezingBlue Flashcards.
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What are the 4 ways to convert invisible ionizing radiation into a visible image?RXCN
- radiography
- xerorediography
- computed tomography
- nuclear scintigraphy
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What uses gamma radiation to scan bone and locate metabolic activity/new growth to pinpoint injury?
nuclear scintigraphy
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Formed with light-sensitive film contained in a cassette.
radiograph
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Holds double-emulsion x-ray film between intensifying screens.
cassette
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Convert x-ray radiation into visible light, thereby creating a latent image on the film.
intensifying screens
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Converted to a visible image via processing
latent image
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Film holder that holds the x-ray film and intensifying screens in close contact.
cassette
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The cassette is _ tight
light
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front of cassette =
plastic
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back of cassette=
lead to prevent backscatter
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How many quadrants may a cassette have?
quad=4 duh
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Name the 3 most common cassette sizes
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Why there a 3x7 cm section of lead on the cassette?
keep film from being exposed
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Film is ID'd where?
dark room
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Decrease the amount of radiation exposure required to produce a diagnostic radiograph
intensifying screens
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Efficiency of the screen depends on what 3 factors?
- high level of x-ray absorption
- high x-ray to light conversion
- little to no afterglow
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What do the intensifying screens have layers of?
luminescent phosphor crystals that floresce when struck by x-rays
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95% of film exposure
light
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5% of film exposure
x-rays
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4 layers of intensifying screens:BRPP
- base
- reflective
- phosphor
- protective
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Attaches phosphor layer to cassette
base layer
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reflects light emmitted by phosphor layer back towards the x-ray film
reflective layer
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Made of calcium tungstate or rare earth crystals.
Absorbs x-rays
Emits light
Stops emmitting light immediately after exposure
Phosphor layer
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calcium tungstate crystal
emits blue light
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rare earth crystal
- emits green light
- better than calcium tungstate
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Clear coating on outer surface of screenprotects phosphor layerresists marks and abrasionseasy to clean
protective layer
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What can alter exposure
any foreign material b/t the screen and film
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Intensifying screen speed depends on:CPRD
- crystal size
- phosphor layer thickness
- reflective layer efficiency
- dyes in phosphor layer to decrease blurring
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Quantum mottle
speed artifact due to inc in speed which causes variation in density on flm
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thicker phosphor layer=
more blurry image
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Slow screen sped AKA: HUF
- high definition
- ultra detail
- fine grain
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Slow screen =
_ crystals
_ detail
_ mAs
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Medium screen speed AKA:RMNP
- regular
- midspeed
- normal
- par speed
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Most common screen speed used?
medium
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Medium speed+ _ resolution
good
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Fast screen speed=
_exposure time
_mAs
_crystals
_ detail
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Fast screens can penetrate _ tissues
thicker
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X-ray film has a _ base on both sides with a light sensitive emulsion that contains _ _ crystals.
- polyester
- silver halide crystals
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Processing film does what?
convert the split silver halide crystals to a visable image
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What are the 4 layers of the x-ray film? BAEP
- base
- adhesive
- emulsion
- protective
- covering
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Silver crystals are sensitive to flourescent light emitted by the intensifying screens, but less sensitive to _. This helps them require less radiation.
ionizing radiation
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Exposure range over wchich acceptable densities are produced.
film latitude
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Forgiving film. Accepts variations in exposure factors or processing without a major change to density.
wide latitude
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High contrast film. Requires less change in exposure factors or processing to affect density.
Narrow latitude
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Large crystals
Granier image that lacks definition
fast film speed
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Most widely used in vet med
Compromise between gran and speed
medium film speed
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Small crystals
Less grainy image
Greater definition
slow film speed
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Combined speed of screen and film determines the _ needed.
exposure
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What differs with manufactuers?
film number
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As the speed of the system increases the _ decreases
mAs
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Non-screen film sensitive to _
direct x-rays
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Non-screen films need greater exposure factors because there is no _ of beam from light.
intensification
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What is non-screen film packaged in?
light tight heavy envelopes
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Example of non-creen film?
dental
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2 dental film speeds. Which is faster?(*)
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Film Care:VCL
- ventrically
- cool place(50-90F)
- low humidity (40-60%)
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How often are screens cleaned?
monthly
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What is used to clean screens?
- commerical cleaner
- 70% alcohol
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