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Ch.27 Contrast

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kkaitlyn96's version from 2017-04-17 01:33

Section 1

Question Answer
What is image contrast?differences between densities, allows visibility of detail in our image
Dynamic rangerange of densities (brightness)
Window widthdynamic range that can be manipulated to change the grayscale/ contrast
Grayscalerange of colors applied to each pixel, algorithms
Window lengthrange of brightness that can be manipulated on the image
memorize

Section 2

Question Answer
High contrastfew shades of gray, short scale, black and white, increased contrast
Low contrastMany shades of gray, long scale, decreased contrast
High kVp= high or low contrastlow
Low kVp= high or low contrasthigh
Physical contrasttotal range of density values recorded by the IR
Visible contrasttotal range of density values seen by the human eye
Radiographic contrasttotal amount of contrast from anatomical part and film (how image appears)
memorize

Section 3

Question Answer
Look up table applied through algorithms that are set to a specific contrast and brightness for a exam
Histogramgraphs energy values
Increase kVp, _________ intensity range, _________ contrastincrease, decrease
Increase differences in material, _________ contrastincrease
Increase atomic number, _________ attenuation, _________ contrastincrease, increase
Can you evaluate contrast without sufficient densities?no
Can you have density without contrast?yes
Can you have contrast without density?no
memorize

Section 4

Question Answer
What is the controlling factor of contrast?kVp
kVp decreases, photoelectric absorption _________, attenuation _________, contrast _________increases, increases, increases
kVp increases, comptons _________, scatter _________, contrast _________increases, increases, decreases
kVp needs to be changed _________% to see a visible change in contrast15 or 8%
memorize

Section 5

Question Answer
mAs will only change contrast if the image is _________too dark or too light
Increase in OID, _________ contrastdecrease
Increase filtration, Increase kVp, _________ contrastdecrease
What do grids do to contrast?improve contrast
Increase beam restricting, _________ contrastincrease
memorize

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