[Gate-users] Estimate randoms from ROOT-file

[COMTAT Claude]

Ida,

 

You can choose to store both prompt and delayed coincidences in the root output. Then, using ROOT, you can rebin delayed coincidences just like ordinary (prompt) coincidences, and then subtract the delayed from the prompts at the sinogram level.

 

Claude

 

 

________________________________

De : ida.haggstrom at gmail.com [mailto:ida.haggstrom at gmail.com] De la part de Ida Häggström
Envoyé : jeudi 11 mars 2010 11:46
À : COMTAT Claude; gate-users at lists.opengatecollaboration.org
Objet : Re: [Gate-users] Estimate randoms from ROOT-file

 

Hi Claude!

Thank you for your reply! I've briefly started looking at the delayed window but have not gotten so far yet. I've looked in the users guide but not been able to figure it all out yet... Using ROOT output, do you know if the delayed coincidence branch can be rebinned into sinograms just like the ordinary coincidence data (and then subtracted from the ordinary sinograms)? Or is this correction implemented directly by GATE, i.e. GATE subtracts the randoms from the prompts directly?

Thanks!

Ida

 

Den 11 mars 2010 10.36 skrev COMTAT Claude <claude.comtat at cea.fr>:

Hi Ida,

Rather than estimating the random coincidences from the singles, you can simulate a delayed coincidence window within Gate in addition to the prompt coincidences, and use it to correct for random coincidences.  To add a delayed coincidence window, see the users guide:

"By default, the offset value is equal to 0, which corresponds to a prompt    coincidence sorter. If a delayed coincidence sorter, with 100 ns time shift, is to be simulated, one should specify the offset value with the command:
/gate/digitizer/Coincidences/setOffset 100. ns"

Claude

-----Message d'origine-----
De : gate-users-bounces at lists.opengatecollaboration.org [mailto:gate-users-bounces at lists.opengatecollaboration.org] De la part de Ida Häggström
Envoyé : jeudi 11 mars 2010 09:39
À :
Objet : [Gate-users] Estimate randoms from ROOT-file


Hello!

I'm trying to create a randoms sinogram (not the "true randoms", but an
estimate) to use for randoms correction for later reconstruction in STIR.  I
guess the most common way is to use the singles countrates for each LOR (?).
I am not familiar with ROOT so I'm having some problems... Has anyone
managed to estimate the randoms from the ROOT output files? I would really
appreciate any help!

Thanks!
Ida

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