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56 Cards in this Set
- Front
- Back
Along with contrast allows detail to be seen |
Density |
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Degree of blackening from black metallic silver deposition on film |
Film density |
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Adjustable component at the monitor, represents how much light is being emitted from the monitor, window level, changes overall lightness and darkness of image |
Brightness |
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To much density is ___, to much information recorded, to much penetration, to bright or light |
Overexposed |
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To little density is ___, to much beam attenuation, diagnostic info did not reach IR |
Underexposed |
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Multiple variables influence __ thereby influencing image __ |
Exposure, density |
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Primary adjustor, exposure determines density, directly proportional, controls density, |
mAs |
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As mAs goes __ exposure goes __ proportionally, so density goes __ |
Up, up, up |
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Digital is always a __ relationship |
Linear |
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Film is linear only along the __ part of the D log E curve only |
Straight line |
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mAs reciprocity |
Exposure=intensity x time |
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Intensity of exposure |
mA |
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Length of exposure |
Time |
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Depends on exposure but independent of the components |
Density |
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Interchange __ and ___ as long as __ is the same, ___ will be the same |
mA, time, mAs, density |
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Occurs at extremely short or long exposure, inadequately calibrated equipment |
Reciprocity failure |
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The 30% guideline is for __ only |
Film |
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Why do you have to change mAs by at least 30% on film |
Can only see a visible change after changing mAs by 30% |
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Why does the 30% guideline not apply to digital |
The histogram will control small to fairly large density adjustments |
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If density needs adjustment on film what do you do |
Double the mAs to make darker, cut mAs in half to make lighter, anything less image does not need repeating |
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With digital systems typically mAs adjustments will only need to be ___ to correct quantum mottle |
Increased |
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On digital what will tell you if technique can be decreased next time around |
EI# |
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If kVp goes up, scatter goes __, so density goes __ |
Up, up |
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If kVp goes up, penetrability goes __, so density goes __ |
Up, up |
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If kVp goes up,# of interactions at the target goes __, so __ xray photons are produced (quantity) |
Up, more |
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Affects quantity and quality |
kVp |
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Preferred method for density adjustments is through |
mAs |
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Non linear relationship between a change in __ and __ |
kVp, density |
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Increase the kVp by 15% to double exposure to the IR, and cut mAs in half, will affect image contrast, influenced by tissue type, *more effectively use when a change in contrast is needed |
15% rule |
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What kVp range does the 15% rule work best |
60-100 kVp |
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With the same technique if a large focal spot is used and then a small focal spot what should not change |
Density |
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What side of the is beam intensity greater |
Cathode |
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This describes the change in exposure intensity when distance change |
Inverse square law |
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change SID but keep same exposure what do you use |
Direct square law |
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Going from 40" to 56" what would you do to mAs |
Double |
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From 72" to 56" |
Halve |
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From 40" to 72" |
Double then double again, should put exposure with in 50% range of pervious |
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This type of filtration reduces exposure by eliminating soft xrays |
Inherent/added |
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Type of filter that affects IR exposure and therefore density |
Compensating |
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As beam restriction increases (FOV gets smaller) IR exposure will __ |
Decrease |
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Will reduce the number of photons, reduce scatter and patient dose |
Collimating |
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Affects beam attenuation, inverse relationship with density, non linear relationship with density |
Tissue thickness, atomic #, tissue density (amount of atoms in area) |
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Radiopaque like Ba or I, positive or negative contrast |
Positive |
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Radiolucent like air or gas, positive or negative contrast |
Negative |
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__ has similar effective atomic # as fat and water |
Air |
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Larger tube angles create __ parts |
Thicker |
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What absorbs scatter |
Grids |
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The characteristics of IRs such as phosphor sensitivity will influence photon energy absorption and therefore IR __ |
Exposure (and density) |
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With digital post processing has a greater influence on what you __ |
See |
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With film what indicates how much xray energy is needed to achieve an exposure for a given speed cassette |
Speed numbers |
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Film density will also be affected by (this is most overlooked) |
Processor chemicals |
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Developer concentration to high, film in developer to long, developer temp to high |
Increased film density |
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Processor chemicals contaminated, and become less effective |
Decreased density |
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With digital what indicates how much exposure the IR received |
EI# |
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There is greater __ with digital |
Latitude |
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Enough __ is needed for the computers __ to adjust the information into the visible range |
Exposure, histogram |