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Forum: Medical Applications
Re: Question Bragg peak of 330Mev/u of carbon using Hadrontherapy example (Morad Hamad)
Date: 24 Apr, 2010
From: G.A.P.Cirrone <G.A.P.Cirrone>

On Wed, 21 Apr 2010 08:38:56 GMT, Morad Hamad wrote:
> Dear users/developers,
>
> when I ran default proton_therapy.mac I get a good Bragg peak which is
> agreeing with the experimental data includes inside the code. However,
> when I try to use ion_therapy.mac to compare it with 330 Mev/u of
> carbon12 from GSI, which has an experimentally a peak at about 20 cm in
> water I get a peak at about 6 cm, also I get the same depth when using
> energy of 135 Mev/u.
> I only changed the energy inside ion_therapy.mac to be 330 Mev/u once
> and 135 Mev/u other.
> I still don't know what is the physical meaning of sigmaenergy variable.
>
> Is the error because I don't use GSI synchrotron geometry? Or that I
> have to change other things inside either the code or the macro files?
>
> Please see the attached Bragg peak for 330 Mev/u of carbon-12.
>
> I will be appreciated for your assistance to solve the problem.
>
> Respectfully,
>
>
> Attachment:
>
> http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2010/04/21/01.29-26308-330MevOfCarbon.jpg
>
> http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2010/04/21/01.29-26380-330MevExperimental.jpg
>

Dear Morad,
it simply seems to me that you are not changing correctly the energy of the carbon ions.

Firstly check the following points:
1.- The energy of your ions must be 330*12 = 3960 MeV as Geant4 requires the total kinetic energy and not the energy per nucleon

2.- Try to change the energy of the beam directly in the HadrontherapyPrimaryGeneratorAction.cc class file (where now the energy for a proton beam is defined as default), so to be sure that you are setting the correct energy value. I have in fact, the suspect that some default is changing the energy you set in the macro file.

Can you please report what version (both of Geant4 and Hadrontherapy) are you using?

Looking into the plot you show I must also recommend you to change the slice thickness of the phantom as, in the case of a carbon beam, the Bragg peak is very narrow and you need very thin slices to achieve a correct spatial resolution. I can suggest you to try to use a 50 micron slice with a 1 micron step max and 5 micron of production cut inside the detector.

Hoping this can help you,
regards,
Pablo Cirrone

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1 Question: Re: Bragg peak of 330Mev/u of carbon using Hadrontherapy example   (Morad Hamad - 29 Apr, 2010)
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