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Radiation Exposure in Digital Imaging
N/A
28
Physics
Professional
03/27/2013

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Term
DR systems have an extremely ___ tolerance for patient over exposure
Definition
high
Term
screen film image can display only approximately ___ shades of gray
Definition
30
Term
in digital imaging, image contrast ___ change with dose
Definition
does not
Term
___ no longer controls contrast in digital imaging
Definition
kVp
Term
___ no longer controls optical density
Definition
mAs
Term
practitioners have the opportunity to reduce patient dose by __-__% depending on exam
Definition
20-50
Term
kVp values range from __ to __ for CR
Definition
45-120
Term
optimum kVp ranges for CR are from __ to __
Definition
60-110 kVp
Term
image density/brightness on the display monitor is controlled by ___
Definition
window leveling
Term
occurs when an insufficient amount of light is produced and image is grainy
Definition
quantum mottle/noise
Term
the two important factors that should be considered when selecting CR imaging cassette
Definition
type and size
Term
the two types of imaging plates
Definition
standard and high resolution
Term
these imaging plates are used for extremities, mammography, and other exams requiring increased detail
Definition
high resolution imaging plates
Term
cassette selection for CR images is ___ critical than screen film images
Definition
more
Term
using the ___ imaging plate possible for each examination results in the ___ sampling rate
Definition
smallest, highest
Term
grid use in CR occurs ___ often due to sensitivity of IP to scatter
Definition
more
Term
grid selection will depend on
Definition
part size
kVp
scatter clean up desired
grid frequency
Term
a wavy artifact that occurs if scan laser and grid lines are parallel
Definition
moire effect
Term
number of grid lines per centimeter/inch
Definition
grid frequency
Term
the __ the frequency, the ___ the grid lines and the ___ they interfere with the image
Definition
higher, finer, less
Term
typical grid frequency
Definition
80-152 lines/in
Term
the relationship between the height of the lead strips and the space between the lead strips
Definition
grid ratio
Term
the ___ the grid ratio, the ___ scatter radiation absorbed and the more ___ the positioning
Definition
higher, more, critical
Term
most grids chosen by departments are ___ and ___
Definition
parallel and focused
Term
parallel grids are __ critical in beam centering, but should not be used at distances less than ___in
Definition
less, 48
Term
on cassettes ____ or smaller it is important to select a high frequency grid to eliminate scatter
Definition
10x12"
Term
___ results in an increased contrast and reduces amout of grid cleanup necessary
Definition
collimation
Term
a postprocessing feature that allows black background to be added around the original collimation edges, eliminating white or clear distracting areas
Definition
shuttering
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