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24 Cards in this Set
- Front
- Back
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Name 3 types of diagnostic radiographic tube-support systems.
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Overhead, floor-to-ceiling, floor, mobile, and C-arm
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Whatare the 2 types of incoming line current?
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Single phase and three phase
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How many pulses are there per Hz for 1 phase and 3 phase power?
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single = 2 pulses
three = 3 pulses |
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What devise in the x-ray circuit controls kVp? mA? time?
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kVp = autotransformer
mA = variable resistor time = timer circuit |
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What is the approximate voltage ripple for 1 phase 2p equipment? 3 phase 6P? 3 phase 12P?
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1/2 pulse = 100%
3/6 pulse = 13-25% 3/12 pulse= 4-10% |
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What happens to the tube mA during an exposure using a falling load generator?
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permits a greater use of the acceptable tube limits
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What is the difference b/w an ionization chamber and a phototimer?
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Ionization chambers is a gas-filled enclosure containing + and - electrodes that measures the amt of radiation passing through the enclosure according to the degree of ionization caused by the radiation. Phototimer is a photoelectric device that automatically controls photographic exposures
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What factor determines the minimum reaction time?
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it is determined by the length of time necessary for the AEC to respond to the radiation and for the generator to terminate the exposure.
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What is the approximate % of electron energy that is converted ot x-ray photon energy int ethe x-ray tube?
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99 percent
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The majority of the electron energy in the e-ray tube is converted to what from of energy?
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Heat
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Describe a bremsstrahlung target interaction?
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Occurs only when the incident electron interacts with the force field of the nucleus.
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Describe a characteristic target interaction.
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Occurs only when the incident electron interacts with an inner shell electron
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What is a characteristic cascade?
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An outer shell electron has dropped to fill the hole & another electron will drop to fill that hole it left & so on until only the outermost shell is missing an electron.
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What is the average keV of the primary beam as compared to the kilovoltage peak?
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30-40%
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What effect does increasing mAs have on the total x-ray emission spectrum?
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mAs controls the quanity of electrons striking the target the result is a change in the amplitude of the emission graph.
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What effect does increasing kVp have on the total x-ray emission spectrum?
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kVp controls the quality of the electrons striking the target resulting in a change in the # of higher energy photons & amplitude of the emission graph.
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Define attenuation
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the reduction in the # of x-ray photons in the beam and subsequent loss of energy as the beam passes through matter
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Describe the photoelectric absorption interaction.
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is when an x-ray photon interacts with an inner shell electron, the photon ejects the electron from is inner shell & is totally absorbed in the interaction
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Describe the Compton scatter interaction
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occurs when an incident x-ray photon interacts with a loosely bound outer-shell electron removes the electron from its shell & then proceeds in a different direction as a scattered photon.
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What is backscatter?
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is when a scattered photon is deflected back toward the source it is traveling in the direction opposite to the incident photon
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What are the two interactions which have a significant impact on the radiographic image?
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photoelectric absorption and Compton scattering
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What type of radiographic contrast will result if the prevalent interaction is photoelectric absorption?
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High-contrast images
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Describe the coherent scatter interaction
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is an interaction which occurs b/w very low energy x-ray photons and matter
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What type of radiographic contrast will result if the prevalent interaction is Compton scatter?
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Low-contrast images.
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