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20 Cards in this Set
- Front
- Back
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who discovered x-rays
and what was he expiramenting with? |
Roentgen in 1895
Cathode ray tube |
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x-rays produce what?
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ionization--
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what is ionization?
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the ejection of an orbiting electron from an aton
it produces ion pairs or free radicals (unstable) |
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Alternating Current Electricity
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movement of e(-) along a wire toward a (+) charge
*the direction of movement changes 60 times per second (thus, x-ray units produce 60 bursts of impulses of radiation per second) *So, .5 second exposure setting is 30 impulses, .25 is 15 impulses, etc.. |
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Amps (Amperes)
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NUMBER of e- in a current at a given time
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Voltage
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potential difference between - & +
therefore... SPEED or FORCE of moving e- toward the + charge |
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electron are ________ charged and are attracted to the ________ charge of the ________.
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negatively
positive anode |
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where do electrons originate?
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cathode
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what do e-'s collide with to produce x-ray photons?
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tungsten target
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The faster the e- move, the greater the collision and more energetic or penetrating the photons... Will an x-ray such as described above have a short or a long wavelength?
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SHORT length
High frequency |
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Milliamps (mA)
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one thousandth of an ampere
amount of e- flowing through the wire each second |
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Kilovolt (kVp)
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speed of e- as they collide with the targed
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What does the aluminum filter do?
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absorbs weak/soft x-rays
reduces total number of photons, but increases percentage of hard photons |
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as exposure time goes up, ______ photons are produced?
(more, fewer) |
more
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If you increases distance from film, will it increase or decrease the amount of photons that strike the film?
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decrease because of the angle the x-ray spreads at < more are lost to surroundings
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what are the 2 measures of x-ray quality?
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density & contrast
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Density
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degree of blackening/blackness
too little density appears too light too much density appears too dark *depends on # of photons reaching film *affected by mA, kVp, filtration, exposure time, distance |
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Contrast
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contrast between areas of interest on film (blacks, whites, greys)
*many grey levels=low contrast *mostly black & white w little grey=high contrast *affected by kVp & filtration only (percent of highly penetrating/hard photons that reach film |
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40 kVp =
60 kVp= 100 kVp= |
*high contrast (short scale)--great for caries
*medium scale *low contrast (long scale)--might be better for soft tissue that high contrast |
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glands
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organs that secrete hormones
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