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Re: Radon forward projection problem [message #60021 is a reply to message #59931]

Sun, 27 April 2008 04:16

Wox
Messages: 184
Registered: August 2006

Senior Member

On Thu, 24 Apr 2008 12:22:44 -0400, mmiller3@iupui.edu (Michael A.
Miller) wrote:

>>>> >> "Wox" == Wox <nomail@hotmail.com> writes:
>
>> Now what is OSEM doing?
>
> OSEM uses a different subset of the data for each iteration. For
> example, if you were running with 8 subsets, you'd use data from
> angles 0, 7, 15, ... for the first iteration, the data from
> angles 1, 8, 16, ... for the second iteration, 2, 9, 17, ... for
> the third and so on in order - hence the name ordered subsets EM.
> Each subset is handled using regular EM. Note that each subset
> must be a reasonably complete measurement by itself. If too many
> subset are used, the signal-to-noise in each subset will approach
> zero and the method won't do any thing useful.

Ah, so I'm using MLEM :-). However, my initial problem still stands.
What should one do when FP(v) is zero in some pixels, that is in
formula
v'=v * BP(s0/FP(v))/BP(s1)

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[Message index]

		Radon forward projection problem By: Wox on Tue, 22 April 2008 08:07
		Re: Radon forward projection problem By: Wox on Thu, 24 April 2008 04:14
		Re: Radon forward projection problem By: mmiller3 on Thu, 24 April 2008 09:22
		Re: Radon forward projection problem By: mmiller3 on Wed, 23 April 2008 09:53
		Re: Radon forward projection problem By: Vontobel Peter on Wed, 23 April 2008 03:42
		Re: Radon forward projection problem By: Wox on Wed, 23 April 2008 03:02
		Re: Radon forward projection problem By: Vontobel Peter on Wed, 23 April 2008 00:42
		Re: Radon forward projection problem By: Wox on Sun, 27 April 2008 04:16
		Re: Radon forward projection problem By: mmiller3 on Mon, 28 April 2008 06:33

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