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61 Cards in this Set
- Front
- Back
Exposure time symbols |
T or s |
|
Time= (symbol) |
s |
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Time is in |
Units of seconds or fractions of seconds |
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Longer exposure time results in production of ___ x rays and ____ image |
more (quantity) ;darker |
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Long exposure times may result in ___ ___ |
Motion artifact |
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What do automatic exposure devices (AEC) do? |
Terminate exposure |
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A measure of current flow rate |
mA |
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Number of electrons |
Quantity |
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Since _ and _ work together to determine the total quantity of xrays, high ___ is used to shorten exposure time to decrease motion artifact. |
mA; s; mA |
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___ x ___ = ___ or milliampere-seconds |
mA; s; mAs |
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MA settings of 150 or less use ___ focal spot. |
Small |
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Higher ___ settings also produce more heat. |
mA |
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Tube can handle high heat doses more effectively with lower ___ and longer ___. |
mA; exposure time |
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kVp - |
Kilovoltage peak |
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kVp determines wavelength of radiation and thus its _____ _____. |
Penetrating power |
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The greater the penetrating power, the more ___ ___reaches the film. |
remnant radiation |
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What determines the quality of the beam? |
kVp |
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An increase in ___ = darker image |
kVp |
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___ is measured in inches or feet |
Distance |
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The distance from the source (tube target) to the image (IR) is |
SID |
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SID affects the ____ (# of photons per square inch) of the xray beam. |
Intensity |
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Because of the divergence of the beam as ____ increases, _____ decreases. |
distance; intensity |
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What is the inverse square law? |
Intensity of the radiation is inversely proportional to the square of the distance. |
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Square inverse law formula |
Intensity= 1/d^2 |
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What are the common cassette sizes |
8×10, 10×12, 14×17 |
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Not so common cassette sizes |
14×34 |
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Intensifying screens do what to needed exposure? |
Reduce exposure needed by 50-100 times. |
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Only 5% of film density is due to ___. |
Xrays |
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Detail screens are only used for what exams? |
Tabletop work of extremities. |
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Film is ___ or ___ light sensitive film. |
Green; blue |
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Intensifying screen crystals must match the ____. |
Film |
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Film can be processed in: |
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Filmless radiography includes: |
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All images are managed in a system called: |
PACS (Picture Archiving and Communication System) |
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Four elements of image quality are: |
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Optical density- |
The overall blackness of the image due to the amount (quantity) of remnant radiation reaching the IR. |
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Optical density is primarily controlled by |
mAs |
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Contrast- |
A variation in density and determines the appearance (quality) of the image on the film. |
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Contrast is primarily controlled by |
kVp |
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Contrast and density are ___ |
interdependent |
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You can have ____ without ___, but you cannot have ___ without ___. |
Density, contrast, contrast, density |
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If there is a big difference between shades of black and white, then contrast is ___ and there are few shades of grey resulting in less detail. |
High |
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High contrast is also called |
Short scale or narrow latitude |
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Decrease __to get higher contrast |
kVp |
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If there is a small difference in adjacent shades of black and white, then contrast is __ and there are many shades of grey which can also result in less detail |
Low |
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Low contrast is also called |
Long scale or wide latitude |
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With low contrast image has an overall ___ appearance. |
Grey |
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Increase ___ if low contrast is desired. |
kVp |
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Image detail- |
The sharpness of the image |
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___ ____ has sharp lines and edges. |
High definition |
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___ ____ has less distinct lines and edges. |
Low definition |
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Detail is affected by:(5) |
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Detail is a affected by:(2) |
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Detail __ as SID increases |
Increases |
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Detail ___ as OID increases |
Decreases |
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Distortion- |
The misrepresentation of the true size and shape of an object |
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Size distortion in xrays is in the form of __. |
Magnification |
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Shape distortion is unequal magnification is due to ___. |
Angulation |
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Factors contributing to distortion/magnification:(3) |
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Magnification ___ as OID ___ |
Increases; increases |
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Magnification ____ as SID ____ |
Decreases; increases |