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28 Cards in this Set
- Front
- Back
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Directly proportional |
as one quantity increases the other increases |
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Proportionality |
a relationship between two numbers |
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indirectly proportional |
as one quantity increases the other decreases |
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What is the inverse square law? |
intensity of x-ray beam= 1/D2 D=distance the intensity decreases rapidly as the distance from the source increases |
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How much of the electric current is produced as heat and how much as x-rays? |
99% heat 1% x-rays |
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What is an x-rays dual nature? |
can behave as a particle as well as a wave |
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What type of x-ray beam is the most harmful to the patient? |
soft x-rays |
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What are the physical properties of x-rays? |
can penetrate that which reflects visible light can cause some substances to fluoresce produces a latent image on film travel in a straight line not electrically charged |
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What does lead protect against? |
scatter radiation only |
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Polychromatic or Heterochromatic |
all beams are of different strength beams of lower energy are filtered out increasing the average energy |
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soft x-rays |
weak beams bounce off scatter or hit film |
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Hard x-rays |
strong beams |
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Film fog |
non-useful radiation hitting the film decreases resolution of image non image forming |
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Beam attenuation |
interaction of x-rays and matter Absorption Deflection=scatter |
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what does attenuation vary with? |
energy of the primary beam density of the matter atomic number of the matter |
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What does interaction with matter produce |
heat fluorescence excitation ionization |
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How does kVp effect the amount of scatter? |
higher the setting, the more radiation |
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How does field size affect the amount of radiation? |
bigger the field size, the more scatter there is |
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Filament |
looks like light bulb always in cathode produces cloud of electrons |
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Target |
part of anode produces x-rays |
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Window |
Radiation comes out |
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Exposure factors |
Ma time MaS KvP |
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KvP |
determines how fast electrons travel to target increase KvP= increase in x-rays thicker body parts require more KvP |
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Time |
Exposure time in secs |
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MaS |
Ma x secs exposed longer time= blacker film |
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What tissue gives the greatest attenuation of the beam, and what is the color of the resulting image? |
Bone and the color is white |
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What physical property is associated with radiation safety in terms of the ability to lower the required exposure for a radiograph to be taken by use of an intensifying screen? |
cause substances to fluoresce |
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What is the x-ray tube? |
a vacuum tube containing an anode and a cathode |
