[gate-users] source of germanium68

Tue Jun 14 20:47:42 CEST 2005

Hi Dimitri,

Thanks for the email.  I had forgotten what the problems were with what Eric said and now remember this conversation from last year.

Dirks solution works but at present Geant4 still (4.7) has some bugs (a memory leak).  This effect can be reduced by modifying the code in Geant4 slightly but it only makes the memory leak build up more slowly.  For short runs with a lot of memory this is not to bad but if you need longer runs then it will eventually cause the program to crash.  I have done some short runs and the results seem fairly good.

ross

-----Original Message-----
From: gate-users-bounces at lphe1pet1.epfl.ch [mailto:gate-users-bounces at lphe1pet1.epfl.ch] On Behalf Of dimitris
Sent: Tuesday, June 14, 2005 3:37 AM
To: 'GATE feedback and helpline for Users'
Subject: RE : [gate-users] source of germanium68

Hi Ross, Eric	

Last year we have created a beta spectrum for I124 using Ross's approach with the Ge68 source. After that we have done what Eric suggests in his e-mail for the gammas of the I124 adjusting the activity levels and placing them in the same location as the source containing only the beta decays exactly as Eric describes on his e-mail. This is all feasible but where everything falls apart is on the temporal information if you do it this way. A lot of the gammas are on cascade and therefore they have to be interconnected in terms of timing to the beta decays, which is not possible using this approach. 

If you look at the singles spectra then we were getting a very nice agreement between the ion source and the combined beta+gamma spectra source, but for the formation of coincidences we tried different things, including different temporal binning options and combinations outside GATE, but never managed to get any reasonable results. 

At that point Dirk (Juelich) announced a simpler way to reduce the time problems associated with using an ion source with GEANT4 and we therefore stopped our efforts. I am still however confused about possible issues associated with "bugs" that Dirk has also discovered in relation to the specific option for the ion source description? Dirk could you comment where we are with this?

Dimitris

--------------------------------------------
Dimitris Visvikis,
U650 INSERM,
Laboratoire de Traitement d'Information Medicale (LaTIM), Equipe 'Quantification en Tomographie d'Emission', CHU Morvan, 5 avenue Foch, 29609 Brest, France

Tel: +33(0)298018114
Fax: +33(0)298018124
e-mail: dimitris at univ-brest.fr
www: latim.univ-brest.fr

-----Message d'origine-----
De : gate-users-bounces at lphe1pet1.epfl.ch
[mailto:gate-users-bounces at lphe1pet1.epfl.ch] De la part de Eric Vandervoort Envoyé : 13 June 2005 22:31 À : GATE feedback and helpline for Users Objet : RE: [gate-users] source of germanium68

Hi Ross,
The simplest way I can think of is to just modify the source macros to have seperate beta and gamma sources in the same physical location. You could just scale the activities of each source by their intensities. So for Ga-68 would use your existing beta spectra with 88% of the total activity and then add the important gammas using monoenergetic gamma sources. I guess the important one is the 3% intensity 1077 KeV gamma. It doesn't look like it would be very easy to add a mixed gamma and beta particle source to GateGeneralParticleSource.cc. I've been trying to avoid hacking the Gate code unless absolutely necessary. Best Regards, Eric

On Mon, 13 Jun 2005, Schmidtlein, Ross/Sloan-Kettering Institute wrote:

> Hi Eric,
>
> Adding the decay gamma's would make this source pretty complete.
I wasn't quite sure how to add them so I never went any further with it.  If you have any ideas on how to do this it might serve as a template for adding other e+ decays with cascade gamma's such as Y-86.  Any ideas?
>
> ross
>
> -----Original Message-----
> From: gate-users-bounces at lphe1pet1.epfl.ch
[mailto:gate-users-bounces at lphe1pet1.epfl.ch] On Behalf Of Eric Vandervoort
> Sent: Monday, June 13, 2005 2:50 PM
> To: GATE feedback and helpline for Users
> Subject: RE: [gate-users] source of germanium68
>
>
> Hello Ross and Murial,
> Thanks for the code, Ross. It looks like your spectra are much closer
to the exerimental Ge68/Ga68 spectra than what I've been using. Thanks, Eric
>
> On Mon, 13 Jun 2005, Schmidtlein, Ross/Sloan-Kettering Institute
wrote:
>
> > Hi Eric and Murial,
> >
> > I added a Ge68/Ga68 source a while back it may be in the archives (I 
> > ignored the gamma's but I did add a specific output for each beta 
> > decay branch).
> >
> > ross
> >
> > Original Message....
> > Hi Sebastien,
> >
> > I completed modifying the code to better represent the spectrum for
> positron emission from Ga-68.  The details are commented in the code.
I checked it against http://ie.lbl.gov/toi.html and it looks very close.
> >
> > ross
> >
> > -----Original Message-----
> > From: gate-users-bounces at lphe1pet1.epfl.ch
> > [mailto:gate-users-bounces at lphe1pet1.epfl.ch] On Behalf Of
evander at phas.ubc.ca
> > Sent: Monday, June 13, 2005 1:49 PM
> > To: GATE feedback and helpline for Users
> > Cc: mviala at clermont.in2p3.fr; gate-users at lphe1pet1.epfl.ch
> <> Subject: Re: [gate-users] source of germanium68
> >
> >
> > Hi Murial,
> > I've added a Ge-68 Beta-energy spectrum to Gate. I attached the
source
> > code to this email. Just put the files with extensions .cc in the
gate/src/ and the .hh files in your gate/include directory, and recompile Gate. You can get the right germanium spectrum and half-life by using the
> > commands:
> >
> > /gate/source/LINE/setForcedHalfLife 2.34101E+007 s 
> > /gate/source/LINE/gps/energytype Germanium68
> >
> > I've emailed you directly so you will get the attachments but I 
> > imagine that these attachments will be scrubbed for the other 
> > gate-users.  If anybody else wants them, I guess you can email me 
> > directly.
> >
> > One thing I should note, though: I've used a different model for the 
> > energy spectrum than the other Gate beta spectra. I just use the
Fermi spectrum for the kinetic energy (KE) of the beta:
> > KE=sqrt(K^2+2*K*(0.511))(K_max-K)^2(K+0.511) with K_max = 1.899 MeV.
Gate uses some other model that I can't get the reference for (Behrens H and Janecke J 1969 "Numerical Tables for Beta-Decay and Electron Capture Landolt-Börnstein, New Series, Group I" vol 4 ed H Schopper, Berlin: Springer). My equation is praobably good enough for most purposes... it gives pretty much the right spectrum and close to the correct mean (the Fermi mean = 0.800 MeV and the experimental mean 0.836 MeV), but it probably could be a bit more accurate.
> >
> > Best Regards,
> > Eric
> >
> >
> > >
> > >
> > > Hi all,
> > >
> > > I need to know how the spectrum of energy within Gate is coded. 
> > > Which are the emission lines which you took into account?
> > >
> > > I must use a source of germanium68.
> > > Which are the lines which I must take into account to code them in 
> > > Gate?
> > >
> > > Best regards,
> > >
> > >
> > > Muriel
> > > _______________________________________________
> > > gate-users mailing list
> > > gate-users at lphe1pet1.epfl.ch 
> > > http://lphe1pet1.epfl.ch/mailman/listinfo/gate-users
> > >
> >
>
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