[Gate-users] RES: Gate-users Digest, Vol 46, Issue 13

Mon Mar 8 20:15:53 CET 2010

Thanks for gave me some directions.

Best regards,

Cláudia

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Enviada em: segunda-feira, 8 de março de 2010 08:00
Para: gate-users at lists.opengatecollaboration.org
Assunto: Gate-users Digest, Vol 46, Issue 13

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Today's Topics:

   1. Re: septa penetration (Simon Stute)
   2. actor dose calculation (AliAsghar Parach)

----------------------------------------------------------------------

Message: 1
Date: Mon, 8 Mar 2010 10:43:39 +0100
From: Simon Stute <gate.stute at gmail.com>
Subject: Re: [Gate-users] septa penetration
To: "Chen, Yu" <Yu.Chen at umassmed.edu>
Cc: "gate-users at lists.opengatecollaboration.org"
	<gate-users at lists.opengatecollaboration.org>
Message-ID:
	<38e368331003080143k7f5e6f0cgf0394a04340e8edd at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Hi all,

On Fri, Mar 5, 2010 at 10:36 PM, Chen, Yu <Yu.Chen at umassmed.edu> wrote:

> We are using the method Simon mentioned to deal with completely absorption
> cases.
>
> We use Uranium (Z=92?) and density=10000(?) to successfully stop all
> particles in the material. I checked root file to see the ranges are all
> within micrometers.
>
>
I do not know if there is a problem with arbitrary high Z number (Geant4 may
> have a limitation on effective Z?).
>

And yes ... there is a limitation ... I tested it and G4 limits by an
"assert" Z to 101, but it gave me segmentation violation above 98. So the
limit is Z=98 !
And even by removing the assert, segmentation violation are also obtained
above Z=98.

Thanks Yu :-) for the estimation of the range.
Cheers,
Simon

>
>
> Yu Chen, PhD
> Walter Reed Army Medical Center
> Building 2, Room 1H46A
> 6900 Georgia Avenue, NW
> Washington, DC 20307
> Phone: (202) 782-1881
> Fax: (202) 782-0305
> E-mail: yu.chen1 at us.army.mil
>
>
> Date: Fri, 5 Mar 2010 11:22:30 +0100
> From: Simon Stute <gate.stute at gmail.com>
> Subject: Re: [Gate-users] septa penetration
> To: Cl?udia R?gio Brambilla <claudinha.rb at gmail.com>
> Cc: gate-users at lists.opengatecollaboration.org
> Message-ID:
>        <38e368331003050222i4de1dba1n372cfa6659834217 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Hi,
>
> 2010/3/4 Cl?udia R?gio Brambilla <claudinha.rb at gmail.com>
>
> > Hi gate users,
> >
> >
> >
> > I have two questions:
> >
> >
> >
> >
> >
> > 1-      Does anybody knows if gate 5 or 6 could simulate septa
> penetration?
> >
>
> Of course, Gate is a Monte Carlo tool !
> But to know it I think you have to put a point source of gamma (with the
> energy of your choice) in the center of a Lead cube and then calculate the
> mean distance between the point source and the position of final
> interaction
> of your gammas.
>
>
> > Or Are the events absorbed when it hits in a Pb material collimator?
> >
>
> No of course, why it should ?
>
>
> >
> > 2-      Is it possible to introduce any command to force absorb event
> when
> > it hits on shielding to reduce the time of the simulation?
> >
> >
> >
>
> I am also thinking about that now and considering my very little
> understanding of physics around particle transport in matter, I think we
> can
> approach this by defining a new element with a very high Z and a new
> material made of this element with a very high density. As photoelectric
> usually depends on Z^4 and compton only on Z, by setting a very high Z you
> maximize the probability of photoelectric much larger than for compton.
But
> I havn't tested it yet !
> And if anybody more experienced in this domain can correct or confirm
this,
> it would be great !
>
> But if you use Gate_v6 there is also  the possibility to easily assign a
> very high cut for gamma in your collimator volume, it is much more
> convenient !
>
> Cheers,
> Simon
>
>
> >
> > Thanks for help,
> >
> >
> >
> > regards
> >
> > __________________________________
> >
> >
> >
> > Cl?udia R?gio Brambilla
> >
> >
> >
> > _______________________________________________
> > Gate-users mailing list
> > Gate-users at lists.opengatecollaboration.org
> > http://lists.opengatecollaboration.org/mailman/listinfo/gate-users
> >
>
>
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------------------------------

Message: 2
Date: Mon, 8 Mar 2010 14:08:28 +0330
From: AliAsghar Parach <aaparach at gmail.com>
Subject: [Gate-users] actor dose calculation
To: gate-users at lists.opengatecollaboration.org
Message-ID:
	<ebd3a0161003080238x564adaf9m4851da0304f2f2ff at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Dear Gate owners and gaters
please more explain the actor and radiotherapy examples of GATE6.0.0.
especially for dosimetry of voxel phantom with actors.
the information mentioned in gatewiki is not enough for dose calculation of
any arbitrary voxelphantoms.

best regards.

-- 
Ali Asghar Parach,Ph.D. student in Medical Physics,Tarbiat Modares
University,Tehran,Iran

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