Depth dose calculation

emillon779 · March 7, 2023, 10:35am

I want to calculate depth dose in Geant4. I will use the TestEm11 example for this. How can I convert the output values to Gy?

maire · March 8, 2023, 11:31am

examples/basic/B1/src/RunAction.cc lines 100-104 and 138-139

emillon779 · March 8, 2023, 11:38am

I don’t understand completely, could you please give some detailed answer?How should I change these code parts?

weller · March 8, 2023, 12:46pm

github.com

Geant4/geant4/blob/master/examples/basic/B1/src/RunAction.cc#L103


      
          //
          G4double edep  = fEdep.GetValue();
          G4double edep2 = fEdep2.GetValue();
          
          
G4double rms = edep2 - edep*edep/nofEvents;
          if (rms > 0.) rms = std::sqrt(rms); else rms = 0.;
          
          
const auto detConstruction = static_cast<const DetectorConstruction*>(
            G4RunManager::GetRunManager()->GetUserDetectorConstruction());
          G4double mass = detConstruction->GetScoringVolume()->GetMass();
          G4double dose = edep/mass;
          G4double rmsDose = rms/mass;
          
          
// Run conditions
          //  note: There is no primary generator action object for "master"
          //        run manager for multi-threaded mode.
          const auto generatorAction = static_cast<const PrimaryGeneratorAction*>(
            G4RunManager::GetRunManager()->GetUserPrimaryGeneratorAction());
          G4String runCondition;
          if (generatorAction)
          {

github.com

Geant4/geant4/blob/master/examples/basic/B1/src/RunAction.cc#L139


      
              G4cout
               << G4endl
               << "--------------------End of Local Run------------------------";
            }
          
          
  G4cout
               << G4endl
               << " The run consists of " << nofEvents << " "<< runCondition
               << G4endl
               << " Cumulated dose per run, in scoring volume : "
               << G4BestUnit(dose,"Dose") << " rms = " << G4BestUnit(rmsDose,"Dose")
               << G4endl
               << "------------------------------------------------------------"
               << G4endl
               << G4endl;
          }
          
          
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
          
          
void RunAction::AddEdep(G4double edep)
          {

looking at the two code sections, you find one solution to your question, i.e., how to make geant4 provide output values in sensible units. What units does it display in your case?

emillon779 · March 8, 2023, 1:12pm

At first, I actually asked the question for the TestEm11 sample. In this example, I wanted to calculate the dose value in Gy.

maire · March 8, 2023, 4:54pm

The natural solution is to modify line ~74 of SteppingAction.cc: divide by the mass of a bin (to be calculated) before to fill histo 1
If you have only 1 absorber, a more efficient way is to include this division in the normalization factor at end of Run.cc, line ~332
Anyway, you have also to change unit in this factor: Gy instead of MeV

emillon779 · March 8, 2023, 5:18pm

How do I need to change line 74? I don’t quite understand. I think 332 lines in Run.cc will be written Gy instead of MeV.

emillon779 · March 9, 2023, 4:59pm

If the dose to be calculated here is the ionized dose . Then how do I calculate the absorbed dose?