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