[Gate-users] Photons on a ring surface, new detector implementation and readout and new time management

[Miguel Couceiro]

Hi Chen,


Thank you for your suggestions.

In fact it was a stupid mistake to use a 0.1 mm of BGO. 5 cm of lead or
tungsten had been more effective.
But I think I prefer the second approach.


Miguel



Chen, Yu wrote:
> Hi, Miguel, 
>
> Nice questions. 
> I would provide you my opinion on your first question.
>
>
> First, let me ask you a question. What is the material you used in your
> 0.1mm thick crystal? If it is a *NORMAL* (e.g., GSO) crystal, of course
> we should expect a little edep in this thin layer.
>
> Instead, you can describe a virtual material with very large density,, letting
> photons be stopped completely within one step in this thin layer. Then you can figure out
> what are those photon's position, momentum from hit file.  
>
> Another way is to modify GateSteppingFunction (correct name?) and let a track be killed
> when it reaches crystalSD.
>
> My two cents. Hope it helps.
>
>
> 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 Miguel Couceiro
> Sent: Sun 4/29/2007 7:41 PM
> To: Gate-users at lists.healthgrid.org
> Subject: [Gate-users] Photons on a ring surface, new detector implementation and readout and new time management
>  
> Hi all!
>
>
> Is there any way to use GATE to simulate the interaction of photons 
> within phantoms and propagate them to the surface of an annulus, and 
> then save the information needed to continue the simulation in Geant4?
> This is easy to do in Geant4, but I would like to use voxelized phantoms.
>
> I have tried to define a cylindricalPET whith 0.1 mm thick, and disable 
> the module, submodule, etc., and attach the crystalSD to the 
> cylindricalPET. However, the edep of the Hits file is very low, as 
> expected, and there is no information on photon momentum to proceed the 
> simulation in Geant4.
>
> Do you think that creating another sensitive detector, for instance the 
> cylindricalSD, and getting the pre-step point information would solve 
> the problem?
>
>
>
> Another possibility is to implement in GATE the detector that I want to 
> simulate (not crystal based). This means to implement, at least, a new 
> system and readout. Were can I find enough information to do this?
>
>
>
> My last question concerns the Time Management. Sometimes we perform a 
> complete simulation with only one isotope, with the correct digitizer 
> sequence. Then we want to change the activity, for instance to study the 
> count rate performance. Since digigate is must faster then a complete 
> simulation, we could benefit if instead of a single time stamp for 
> singles there was three time stamps: one for positron annihilation, one 
> for photon interaction in the detector after annihilation, and one that 
> would be the sum of the two. This first one could be changed by the 
> digitizer based on the source activity, and last one could be calculated 
> based on the first and second ones. Is there any way to use this 
> approach in digigate?
>
>
> Thanks in advance for your answers,
> Miguel
> _______________________________________________
> Gate-users mailing list
> Gate-users at lists.healthgrid.org
> http://lists.healthgrid.org/mailman/listinfo/gate-users
>
>
>   
-------------- next part --------------
A non-text attachment was scrubbed...
Name: couceiro.vcf
Type: text/x-vcard
Size: 458 bytes
Desc: not available
URL: <http://lists.opengatecollaboration.org/mailman/private/gate-users/attachments/20070501/6e4c67e5/attachment.vcf>