[Gate-users] Gate dose to water problem

Fri Feb 3 11:27:42 CET 2017

Hi all,

I propose to move the detailed discussion on further improvement of dosetowater on the slack in the channel doseactor and agree (as we did for LET actor) about what to do, when to do and who will do it practically in the code + documentation.

Best,
Loïc

-----Original Message-----
From: Andreas Resch [mailto:andreas.resch at meduniwien.ac.at]
Sent: Friday, February 03, 2017 10:11 AM
To: David.Sarrut at creatis.insa-lyon.fr
Cc: Grevillot Loic; gate-users at lists.opengatecollaboration.org
Subject: Re: [Gate-users] Gate dose to water problem

Am 2017-02-03 08:02, schrieb David Sarrut:
> Hello,
>
> as a first workaround, Luc's suggestion is done here :
> https://github.com/OpenGATE/Gate/commit/90327e12eb4559dd838d02d2c1d97e
> 5751251fda
>
> Please test and report.
>
> Sincerely,
> David
>
> On Thu, Feb 2, 2017 at 6:01 PM, Grevillot Loic
> <loic.grevillot at medaustron.at> wrote:
>
>> Hello,
>>
>> Currently the DoseToWater part is incomplete and should contain other
>> particles, e.g. carbon ions, helium, etc.
>>
>> The else part only means at the moment that if the system encounter
>> another type of particle, it will calculate the dose to water
>> assuming this particle is equivalent to a proton with an energy of
>> 100 MeV.
>>
>> If we would remove the if (which could also be an option), then the
>> dose to water would be equal to the dose, as it would not be rescaled
>> by the stopping power ratio.
>>
>> So currently the DoseToWater works for electrons, photons and proton
>> beams as far as I know.
>>
>> I have in my to do list to upgrade it for particles up to carbon
>> ions, but did not have time yet, that being said it should not be
>> very difficult, just require a bit of time and also to find out the
>> correct naming convention used in Geant4 for the different particles
>> that can be generated.
>>
>> Hope this help!
>>
>> Best,
>>
>> Loïc
>>
>> FROM: Manuel Bardiès [mailto:manuel.bardies at inserm.fr]
>> SENT: Thursday, February 02, 2017 5:27 PM
>> TO: Luc SIMON
>> CC: Grevillot Loic; gate-users at lists.opengatecollaboration.org
>> SUBJECT: Re: [Gate-users] Gate dose to water problem
>>
>> And thanks to Andreas as well (Luc missed his mail ;-)
>>
>> Le 2 févr. 2017 à 17:23, Luc SIMON <uhqd75 at gmail.com> a écrit :
>>
>> Dear all and in particular:
>> david.sarrut at creatis.insa-lyon.fr
>> gergely.patay at gmail.com
>> alexvergaragil at gmail.com
>> thomas at deschler.fr
>>
>> AND ALL THE AUTHORS OF DOSEACTOR.CC [1] ...
>>
>> FOLLOWING THE MAIL OF TONY YOUNES WE INVESTIGATED THIS BUG.
>>
>> We found that the NaN values seem to come from DoseToActor.cc [2] at
>> this level (l 360)
>>
>> // Other particles should be taken into account (Helium etc), but bug
>> ? FIXME if (PartName== "proton" || PartName== "e-" || PartName== "e+"
>> || PartName== "deuteron") {
>>
>> DEDX = emcalc->ComputeTotalDEDX(Energy, PartName, material, cut);
>> DEDX_Water = emcalc->ComputeTotalDEDX(Energy, PartName, "G4_WATER",
>> cut);
>>
>>
> doseToWater=edep/density/Volume/gray*(DEDX_Water/1.)/(DEDX/(density*e_
> SI));
>> }
>> else {
>> DEDX = emcalc->ComputeTotalDEDX(100, "proton", material, cut);
>> DEDX_Water = emcalc->ComputeTotalDEDX(100, "proton", "G4_WATER",
>> cut);
>>
>>
> doseToWater=edep/density/Volume/gray*(DEDX_Water/1.)/(DEDX/(density*e_
> SI));
>> }
>>
>> IN THIS "IF" SECTION SOMETIMES DEDX AND DEDX_WATER ARE 0.0 AND THE
>> DIVISION 0 / 0 IS NAN (PLEASE NOTE THAT 3 / 0 IS INFINITE, WHICH IS
>> NOT A NAN VALUE...)
>>
>> This problem is fixed. But now another question : why in the "else"
>> part DEDX_water is computed for proton ????? (while proton should be
>> considered in the first part... )
>>
>> Moreover, photons should not contribute to "dose". So why do we need
>> this "else" part ????
>>
>> Thank you for your help.
>>
>> Luc & Tony
>>
>> 2017-01-31 16:22 GMT+01:00 Grevillot Loic
>> <loic.grevillot at medaustron.at>:
>>
>> Hi,
>>
>> Could you send macros and output files?
>>
>> Best,
>>
>> Loïc
>>
>> FROM: tony youness [mailto:tony_youness at live.com]
>> SENT: Tuesday, January 31, 2017 3:14 PM
>> TO: Grevillot Loic; gate-users at lists.opengatecollaboration.org
>> SUBJECT: Re: Gate dose to water problem
>>
>> Hi,
>>
>> I am simulating high energy photon beams (6 and 10 MeV) for external
>> radiotherapy applications.
>>
>> I tried both ("Water" and "G4_WATER") and I am still getting NAN
>> values (only when the absorbed dose is reported as absorbed dose to
>> water). The voxel values between both absorbed dose report (Dose to
>> medium and Dose to water) are also different even though that the
>> medium is WATER.
>>
>> Regards,
>>
>> Tony
>>
>> On 31/01/17 8:37 am, Grevillot Loic wrote:
>>
>> Hello,
>>
>> Which beam are you simulating? (photons, electrons, light ions,
>> etc.)
>>
>> Which water did you define in your simulation? “Water” is different
>> from “GEANT4_WATER” -> could you try using GEANT4_WATER?
>>
>> Best,
>>
>> Loïc
>>
>> FROM: Gate-users
>> [mailto:gate-users-bounces at lists.opengatecollaboration.org] ON BEHALF
>> OF tony youness
>> SENT: Monday, January 30, 2017 1:04 PM
>> TO: gate-users at lists.opengatecollaboration.org
>> SUBJECT: [Gate-users] Gate dose to water problem
>>
>> Dear All,
>>
>> I am facing a problem with gate dose actor. When enabling dose to
>> water i get Nan values in some of the voxels in the water region of
>> my phantom. I also get different values in the water voxels between
>> both dose reports (dose to medium and dose to water). It seems like
>> there's a bug when gate tries to converts dose to medium into the
>> dose to water when in the water region. Has anyone already faced this
>> problem? Any help would be much appreciated.
>>
>> Kind Regards,
>>
>> Tony Younes
>>
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>> --
>>
>> ___________________
>>
>> SIMON Luc, Physicien Médical, PhD
>> Département d'Ingénierie et de Physique Médicale - IUCT-Oncopole
>> - Toulouse, FRANCE
>>
>> INSERM UMR 1037 (CRCT) - Equipe 15 - Toulouse, FRANCE
>>
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> CREATIS, UMR CNRS 5220, Inserm U1206
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Hi,

I am not sure about the exact definition of dose-to-water, so I might be wrong. However, I would suggest to use the mean energy of post and pre step point for stopping power calculation (it is defined in this way for LET in ICRU 73)? Why do we need this if "proton" in the first place?
Couldn't we just say: if not photon get DEDX?  Sth like this for
example:

 const G4Material* materialTest =
step->GetPreStepPoint()->GetMaterial();//->GetName();
      double energy1 = step->GetPreStepPoint()->GetKineticEnergy();
      double energy2 = step->GetPostStepPoint()->GetKineticEnergy();
      double energy=(energy1+energy2)/2;
      const G4ParticleDefinition* partname =
step->GetTrack()->GetDefinition();//->GetParticleName();

//G4double dedxAR = emcalc->ComputeElectronicDEDX(energyAR, partnameAR, materialAR);
G4double DEDX = 1;
G4double DEDX_Water = 1;
// if not a photon get DEDX
if ( partname->GetPDGEncoding() != 22  )
{
DEDX = emcalc->ComputeTotalDEDX(energy,partname,materialTest, cut);
                 DEDX_Water = emcalc->ComputeTotalDEDX(energy, PartName, "G4_WATER", cut);

}
doseToWater=edep/density/Volume/gray*(DEDX_Water/1.)/(DEDX/(density*e_SI));

if (DEDX_Water == 0 || DEDX == 0) {
GateWarning("DEDX = 0 in doseToWater, Edep ommited");
G4cout<<"PartName: "<< PartName<<" Edep: "<<edep/gray<<G4endl;
doseToWater = 0.0;
}

ANDREAS RESCH, M.SC.
PhD student, Medical Physics

MEDICAL UNIVERSITY OF VIENNA
Department of Radiotherapy
Christian Doppler Laboratory for Medical Radiation Physics for Radiation Oncology
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