I am using the doseDeposit to calculate the dose deposition inside the detector, and I would like to ask if the calculation results are normalized. I have tested three different statistics: 1E4, 1E5, and 1E6, with all other codes being identical. The average Gy values obtained for the scoring region are 3E-10 Gy, 7.68E-10 Gy, and 3.83E-9 Gy, which correspond to total doses of 1.98E-8 Gy, 8.6E-8 Gy, and 1.73E-6 Gy, respectively.
My question is whether the results obtained using doseDeposit are normalized? If they are not normalized and are instead related to the number of particles, the pattern in these results is not linear with a factor of 10 and 100 as expected. Even accounting for statistical errors, the variation does not seem that large.
My .mac code is as followed:
/score/create/boxMesh detectordose
/score/mesh/boxSize 2 2. 2. cm
/score/mesh/nBin 10 10 5
/score/mesh/translate/xyz 0 10. 0. cm
/score/quantity/nOfStep nOfStepGamma
/score/quantity/doseDeposit doseDeposit
/score/close
I cannot account as to why the values are what they are but I can say that, unlike other transport codes, the quantities that you get in Geant4 are NOT “per source”. The values that you get are, in that regards, absolute and you would have to do the normalization yourself.
Again, I cannot comment on why your results do not scale trivially with the statistics.
Dose is proportional to flux and energy
flux are the events, your beam shape design etc.
each event means a particle (that carry energy) interacts in media or your simulation envt.
Now mesh created of some choice. As in your work,
Each voxel is a volume where e1,e2,e3 will deposit in integrated form making total energy deposition in that volume (or voxel) → leading to dose in that volume.
Therefore, it is not normalized in G4 engine.
You need to normalize it explicitly for your purpose.
The total dose deposition is the integration(+sum) of all voxels.
so if you have lateral dose which means the X and Y bins 1 and 1 , whereas Z has bins say any number N,
run your code for different events, keeping above voxel combination fixed, result will be linear provided a fixed i/p energy at a fixed point (say Dmax).
dose = energy fluence x CSDA(or S/p)
S/P change over energy making changes in dose at each steps will lead