Re: [Stir-users] Adding poisson noise to sinogram

[Kris T. <kri...@cs...>]

Hi

The seed is any integer (I think 32bit). You use it to get different "noise
realisations".

The scale depends on your data. It is used to multiply your "mean"
projection data first (and divide afterwards if "preserve_mean" is on). As
you know that the Poisson distribution is scale dependent, you can see why
this is convenient.

As far as the recommended scale, you'd want to make sure that the
scale*mean_projection_data have roughly the same counts as your clinical
data. I'd guess something like 100K per sinogram or so, but it will vastly
depend on your protocol, 2D/3D etc

Kris

> -----Original Message-----
> From: sti...@li... 
> [mailto:sti...@li...] On Behalf Of anvariz
> Sent: 01 June 2010 13:29
> To: sti...@li...
> Subject: [Stir-users] Adding poisson noise to sinogram
> 
> Dear STIR users
> I am working with XCAT phantom.I need to forward project XCAT 
> images and add  
> poisson noise to their sinograms with STIR.I used this command:
>     
>     poisson noise noisy-dynamic  dynamic.hs 1 40
> 
> that noisy-dynamic is the output_file_name and dynamic.hs is 
> the header of my
> input sinogram.
> 
> I don't know which values are better to use for scaling 
> factor and seed?
> What is the regular range for these parameters?
> 
> I appreciate any help.
> Thanks in advance.
> 
> --
> Zahra Anvari
> Tehran University of Medical Sciences
> 
> -- 
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