The flashcards below were created by user
Mshel389
on FreezingBlue Flashcards.
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in a pt coordinating system the z-axis is what?
head to toe
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In a pt coordinating system the x-axis is what?
right to left
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In a pt coordinating system the y-axis is what?
anterior to posterior
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Pixel size = fov divided by?
matrix size
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If FOV decreases without a change in matrix size then what happens?
pixel size will decrease as well
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Digitization consists of 3 steps...
scan, sample & quatize
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Bone is white which is what number on a gray level?
255
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Black is air and is what number on a gray level?
0
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5 fundamentals of digitizing images are:
enhancement, restoration, analysis, compression, synthesis
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Image enhancement does what?
makes image more pleasing to the eye
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Image Restoration does what?
improves quality of images that have distortions
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Image analysis does what?
allows measurements and statistics to be performed as well as image segmentation (3D)
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Image Compression does what?
reduces the size of the image to decrease transmission time & reduce storage space
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2 types of image compression are
Lossless & Lossy
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Lossless AKA?
- Reversible
- No loss of info
- has a ratio of 8:1 or less
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Lossy AKA?
- Irreversible
- Some info is lost forever
- can have ratio above 8:1
- Is not clinically used
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Image synthesis does what?
creates images from other images or non-image data. (ex is reconstruction techniques)
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in Hounsfield Units Air is what?
Black -1000
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In HU scale Bone is what?
White +1000
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Transformation is what?
A lossless step, image is transformed from gray scale values in spatial domain to coefficients in some other domain
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3D visualization Techniques consist of?
Surface Rendering & Volume Rendering
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Surface rendering?
- part of 3D visualization technique
- simple procedure
- surface of an object is created using contour data and shading the pixels to provide the illusion of depth (10% of data in 3Dspace)
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Volume Rendering?
- part of 3D techniques
- Much more sophisticated than Surface
- used all data in 3Dspace to provide additional info.
- Allows observer to view more details inside the object
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Attenuation depends on
electrons per gram, atomic #, tissue density & radiation used
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Displayed FOV can be what compared to the scanned FOV?
Less than or equal to
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