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33 Cards in this Set
- Front
- Back
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Cathode is ___ charged
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negative
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Anode
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positive
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Where is the tungsten filament located?
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the cathode
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When the exposure button is pushed, the electrons travel from the ____ to the ___ and hit the focal spot.
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cathode to the anode, the focal spot is a tungsten target located on the anode
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When the electrons from the cathode hit hit the target, energy is produced in two forms. What are they?
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xrays 1% and heat 99%
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What is the anode embedded in? Why?
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Embedded in copper to dissipate heat
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What is thermionic emission?
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when the xray machine is turned on, the (tungsten) filament releases electrons that form an electron cloud
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T or F, electrons only travel in one direction.
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TRUE from cathode to anode
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What happens when electrons are slowed or moved from their path when they collide with the tungsten target?
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General Radiation or Bremsstrahlung
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If an electron is released from its shell causing electrons to shift to fill the space of the ejected electron, what is this?
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characteristic radiation, happens when the electrons from the cathode collide with the anode
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What requires more energy?
Eject an electron from its shell Move an electron from its path |
eject an electron from its shell
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What kind of radiation is more penetrating?
Characteristic Radiation General Radiation |
Characteristic radiation, they have a shorter wavelength
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Dense objects absorb ____ xrays and appear _______
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absorb MORE xrays and appear radiopaque
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T or F The energy of the xrays impacts the image formation
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TRUE, xrays with more energy will have a greater ability to reach the film
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Xrays or photons are produced at the...
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anode
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what does milliamperage (ampere) do?
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affect the # of electrons released by controlling the temperature of the filament at the cathode.
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What is the range of mA?
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10-15
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T or F mA affects density of the x-ray film and is determined by film speed, exposure time and distance.
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True
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T or F. Density and mA are proportional
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TRUE, as one increases the other increases
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What is the easiest way to alter the density of the film?
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exposure time---the longer you go, the more xrays are released
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What is the conversion rate for impulses and seconds?
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there are 60 impulses in 1 second. 1/4 second equals 15 impulses
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What is kVp?
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it controls the quality of the radiation---does it by controlling the speed of electrons traveling from the cathode to the anode. It influences penetration, force or energy of x-rays
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As the kVp is increased, the electrons travel with _____ speed
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MORE speed and produce more penetrating xrays.
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kVp setting range
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65-110
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The denser the object, the _____ the kVp setting
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the GREATER the kVp setting
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The kVp setting is usually higher for adults than for children. Why?
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more penetrating xrays are needed to pass through denser objects
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T or F The kVp is proportional to contrast
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FALSE, the kVp is inversely proprotional to contrast. As you increase one, the other decreases
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Low contrast means...
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many shades of gray (long scale contrast) This happens around 90-100 kVp For periodontal evaluation
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Caries will not be seen as clearly at what kVp setting?
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at a high kVp setting
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What setting of kVp is the best for seeing caries?
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around 70
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For every 15 % increase in kVp the density of the film will _____
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double
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T or F if you increase the kVp by 15, it allows for a reduction in exposure time by 1/4
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FALSE, you can reduce the exposure time by 1/2
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What are all of the factors that influence density?
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kVp, filtration (increase filtration, decrease density)
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