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32 Cards in this Set
- Front
- Back
Converts xray photons to light, single or double, within a film cassette |
Intensifying screen |
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99% of the diagnostic image is created by the intensifying screen light emission |
Latent image |
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Less than __% of the xrays landing directly on the film will interact with it |
1 |
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About __ %of the xrays landing on the screens produce light |
30 |
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In the screens what receives the x radiation |
Phosphor--->emit light---->expose film |
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Varies depending on desired resolution and response time (speed) |
Layer thickness |
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High atomic # increases efficiency of xray absorption, higher light photon emission |
Photon characteristics |
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Must emit the same wavelength energy (color) as what the film is sensitive to |
Spectral emission |
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Heat, humidity, any other radiant energy, prevent film fog |
Insensitive to environment |
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Must stop emitting light when xray exposure stops |
No afterglow |
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Must be uniformly radiolucent, chemically inert, flexible |
Base of intensifying screen |
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Between base and phosphor layer |
Reflective layer |
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Sends photons back towards the film |
Reflective layer (greater the # of photons reaching film, less amount of xray is needed) |
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Reduces light scatter and protects resolution, absorbs light photons of longer wavelengths |
Dye within reflective layer |
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Ability to emit light in response to a stimulant, emit light when exposed to xray this is called |
Luminescence |
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What happens when crystal is stimulated |
Outer shell e- receive energy and elevate, as they drop back they release excess energy in the form of light photons |
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The light emissions are of a specific __ representing a particular __ |
wavelength, color |
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Is fluorescence good or bad luminescence |
Good-_light emission only during stimulation |
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Is phosphorescence good or bad luminescence |
Bad- continued light emission post stimulation (aka screen last or after glow, leads to over exposure) |
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How long is screen life |
5-7 years |
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What are the 2 types of phosphor crystals |
Calcium tungstate, rare earth |
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What is the conversion efficiency of calcium tungstate |
5% |
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What is the conversion efficiency of rare earth |
15-20% |
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Smaller crystals, thinner layer more__ but higher patient __ |
Resolution or detail, dose |
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How quickly screens can expose the film is called |
Speed (determined how much xray is needed |
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Faster screens is __ technique __ patient dose |
Less, less |
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Larger the crystals, __ the exposure, __ the screen, __ the dose (good) ,__ resolution (bad) |
Quicker, faster, lower, less |
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Thicker the phosphor layer,__ the screen,__ the dose,__ detail/resolution |
faster, lower, less |
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__ the #, __ the screen, __ the resolution |
Higher, faster, lower |
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Relative speed # detail screens |
100 or less |
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Regular speed |
100-400 |
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High speed |
up to 1200 |