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23 Cards in this Set
- Front
- Back
algorithms
1)essential to the way computers process _______ |
-information
|
|
key points about algorithms (3)
|
-all vagueness is eliminated
-rules are well defined -terminate after a set of number of steps |
|
4 types of data
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-measurement data
-raw data -convolution data -image data |
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fourier transformer
1)converts complex signals in _____ domain into a continuous spectrum of its sine & cosine components in the _______ domain |
-spatial
-frequency |
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the coefficients of the ____ & _____ components make it possible to reconstruct an image in CT
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-sine
-cosine |
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inverse fourier transformer reverts signal from the ____ domain back to ____ domain
|
-frequency
-spatial |
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measurement data is data ____ from the detectors
raw data 1)all data that is obtained from the detectors after it is ______ 2)this is the data that is preserved & also called ______ |
-direct
-preprocessed -scan data |
|
convolution data is various mathematical convolution filters are applied to raw data to remove _____
|
-blur
|
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convolution data has 2 parts
|
-high & low pass convolution filters
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high pass convolution filters improve ______ by suppressing high spatial resolution (represented by bone- soft tissue interfaces)
low pass convolution filters improve ________ by suppressing low spatial frequencies (represented by a soft tissue like the brain & liver tissue |
-contrast resolution
-spatial resolution |
|
image data is known as _________ ______
|
-reconstructed data
|
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pixel
1)____ that represents a small volume in the pt voxel 1)is a volume element that has a _______ associated w it |
-2D
-linear attenuation coefficient |
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the problem in CT is to reconstruct each _____ linear attenuation coefficient from many rays
|
-voxel
|
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back projection is the simplest method
-___ all profiles to obtain an image -causes _____ star patten _____ |
-sums
-classical -artifact |
|
step1 to reconstruction of algorithms
-collect the ____ sums from ____ degree angle & place them in the corresponding pixel elements |
-ray
-0 |
|
step 2 to reconstruction of algorithms
-collect the ray sums from the ____ degree angle & add them to the corresponding pixel elements from step 1 |
-45
|
|
step 3 to reconstruction of algorithms
-collect ray sums from the _____ degree angle & add them to the corresponding pixel elements from step 2 |
-90
|
|
step 4 for reconstruction algorithms
-collect the ray sums from the ______ degree angle & add them to the corresponding pixel elements from step 3 |
-135
|
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step 5 for reconstruction algorithms
-subtract a constant value ____ |
-6
|
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step 6 for reconstruction algorithms
-____ by the common divisor ____ & you have the _____ matrix |
-reduce
-3 -original |
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the fourier reconstruction method is used in _____ but not in ____ cause it requires more complicated math
|
-MRI
-CT |
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____ reconstruction was 1st reconstruction tech used by hounsfield in his brain studies
|
-iterative
|
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________ is the most widely applied reconstruction algorithm in CT
|
-filtered back projection
|