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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

measurement data
raw data convolution data image data 

fourier transformer
1)converts complex signals in _____ domain into a continuous spectrum of its sine & cosine components in the _______ domain 
spatial
frequency 

the coefficients of the ____ & _____ components make it possible to reconstruct an image in CT

sine
cosine 

inverse fourier transformer reverts signal from the ____ domain back to ____ domain

frequency
spatial 

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


convolution data has 2 parts

high & low pass convolution filters


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


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 

the problem in CT is to reconstruct each _____ linear attenuation coefficient from many rays

voxel


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


step 5 for reconstruction algorithms
subtract a constant value ____ 
6


step 6 for reconstruction algorithms
____ by the common divisor ____ & you have the _____ matrix 
reduce
3 original 

the fourier reconstruction method is used in _____ but not in ____ cause it requires more complicated math

MRI
CT 

____ reconstruction was 1st reconstruction tech used by hounsfield in his brain studies

iterative


________ is the most widely applied reconstruction algorithm in CT

filtered back projection
