introduction of computed tomography james chang. history of ct radon-nikodym theory of johann.radon...
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Introduction of Computed Tomography
James Chang
History of CT Radon-Nikodym theory of Johann.Radon G.N.Huunsfeild invented CT in 1972 Nobel Prize in Physiology or Medicine 1979
The generation of CT
Translate-Rotate 1st : pencil beam X-ray and single detector 2st:pencil beam X-ray and mutidector (30)Rotate-Rotate 3st:fan beam X-ray and mutidector (300-
800)Stationary-Rotate 4st:fan beam X-ray and ring
detector(1000-2400) 5st electronbeam (50ms)
http://xic.cc/255-667-1.do
4th Helical CT
http://www.virtualmedicalcentre.com
http://www.imaginis.com/ct-scan/how-does-ct-work
CT from 1st to 4th generation
Original axial CT image from the dedicated Siretom CT scanner circa 1975. This image is a coarse 128 x 128 matrix
Data Acquisition
Sinogram
http://www.physics.ubc.ca/~mirg/home/tutorial/fbp_recon.html
A visual representation of the raw data obtained in a computed axial tomography (CAT) scan.
Sinogram
Filtered Back Projection
Sinogram
1 1 1
1 13 1
1 1 1
3 15 3
1 2 15 2 1
3 15 3
3 15 3
3 15 3
1 2 15 2 1
1 2 15 2 1
1 2 15 2 1
Filtered Back Projection
1 5 1
1 5 1
1 5 13 15 3
1 2 15 2 1
3 15 3
3 15 3
3 15 3
1 2 15 2 1
1 2 15 2 1
1 2 15 2 12 6 6
2 10 2
6 6 2
3 7 7
7 15 7
7 7 3
8 8 8
8 20 8
8 8 8
9 13 9
9 25 9
9 13 9
10 14 14
10 30 10
14 14 10
Filtered Back Projection11 15 15
15 35 15
15 15 113 15 3
1 2 15 2 1
3 15 3
3 15 3
3 15 3
1 2 15 2 1
1 2 15 2 1
1 2 15 2 116 16 16
16 40 16
16 16 16
Without filter
Point object becomes widely spread out
Why do we Apply a Filter ? Another
diagram that illustrates this concept
From Sinogram to Image
Video: http://www.youtube.com/watch?v=kMMyvQF-CYQ&NR=1
Thank you