[Gate-users] ASCII output

[Chen, Yu]

Hi, Simon,

In the following message, you mentioned:

>So if your hits have scattered many
>times in your crystal, I think the position, energy and time stamp mentioned
>are for the last one. And so for your singles, there is a sort of average
>applied by these modules that change the position, energy and time stamp.

Are you indicating that only last scattered photon infomation be recorded and initial incident photon information just simply lost?

If this had been the case for GATE, I think it would be problematic since one single crystal detector could not be able to distinguish incident and scattered photons deposited in it.

My understanding for GATE is the following as sent two days ago:  

>From GATE manual, what I can learn is that Singles is from Pulse, and the latter is given by centroid of hits (weighted by energy).
>What I am not clear is if a Pulse is only related to individual detector. i.e., Can a photon generate and be recorded several Pulses
>in different detectors (crystals) if scatter (and/or penetration) occurs?

>1)If yes, then it is possible to record the first pulse information besides that single (I assume it is centroid of pulses) information.

>2)If no, (that is, one photon, one pulse, one single) we can try to record the first hit information (global X,Y,Z and crystal ID) into
>corresponding Single though they are not experiment-detectable.

>I prefer solution 2), which can give us precise information on how big the scatter and penetration effects are.  

And I tend to believe that above 2) is the case for current GATE: i.e., even an incident photon occurs many scatterings in different crystals
the final output is still one single that takes into account all hits from initial and scattered photons. 

Can any expert clarify this?

Thanks,


Yu Chen, Ph.D.
University of Massachusetts Medical School
Division of Nuclear Medicine
55 Lake Avenue North
Worcester, MA 01655-0243
Phone:  (508) 856-6123
Fax:    (508) 856-4572



-----Original Message-----
From: gate-users-bounces at lists.healthgrid.org on behalf of Simon Stute
Sent: Thu 12/13/2007 5:01 AM
To: ??
Cc: gate-users at lists.healthgrid.org
Subject: Re: [Gate-users] ASCII output
 
Hi Guo Ning,

What I will say is just a suggestion, I am not sure at all.
I think that between hits and singles the Adder, Readout and Blurring
modules of the digitizer are applied. So if your hits have scattered many
times in your crystal, I think the position, energy and time stamp mentioned
are for the last one. And so for your singles, there is a sort of average
applied by these modules that change the position, energy and time stamp.
>From the last column of your ascii hits file, you can see what is the last
volume where a scatter interaction has occurred. So maybe you could see
'crystal' for some. And those which have not scattered in the crystal are
maybe affected by the blurring effects (spatial, energy), if you have fixed
some in your digitizer. Am I clear ?? :-)

Hope it helps,
Simon

2007/12/13, ?? <guoning0225 at gmail.com>:
>
> Dear Gate users:
> Here is question about the ASCII output .
> I want to make clear that what is the relationship between the
> position,energy deposited and the time stamp information presenting
> separately to the Hits file and Singles file.That is to say how does
> the information of these aspects come from in the digitizer mode
> chain,especially from the hits to singles.
>
> As my observation, compared with the same event ID ,the value of
> position,energy deposited and the time stamp in the Hits file
> (gateHits.dat) are different from that in Singles
> file(gateSingles.dat). But there must to be some kind of algorithmic
> connection between them, since they are come from the same event .I
> wonder what is it ,may be a method such as weighted average or some
> others .
> Can anyone tell me the intrinsic relationship of this, thanks for your
> attention.
>
>
>                   Guo  Ning
> _______________________________________________
> Gate-users mailing list
> Gate-users at lists.healthgrid.org
> http://lists.healthgrid.org/mailman/listinfo/gate-users
>

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