I want to investigate the dose of photons as it goes through a cancer, skin, fat, muscle, and bone tissue. With the simulation results, I would like to use it to compare the results with an electron beam that results in equal biological damage to this cancer.
To do this, I use the DOSE-EQ in USRBIN with an AUXSCORE AMB74. The chemical composition of each layer is different. You can see pronounced differences in total deposited dose (DOSE in USRBIN) as the photons go through each layer, however, this difference is significantly less noticeable when using DOSE-EQ. I attached the dose depth profiles.
My question: is the DOSE-EQ affected by the material/layer definitions? Why do I not see such dramatic differences across layers with DOSE-EQ compared to DOSE? Am I missing something?
For simulating the 15 keV photon I am using:
PHYSICS EM-CASCA
EMF-ON
EMF-CUT with 1 MeV for electrons and 1E-7 GeV for photons
These results can be expected since DOSE and DOSE-EQ correspond to two different quantities, which are also estimated differently.
With DOSE you score an absorbed dose, that is energy deposited per unit mass. The results in your first plot reflect the energy deposition in the different materials.
Instead, with DOSE-EQ you score the ambient dose equivalent (H*(10)), that is the dose equivalent that would be produced at a depth of 10 mm from the surface of the ICRU sphere, on the radius vector opposed to the direction of expanded and aligned radiation field. Note that DOSE-EQ scores H*(10) by default, there is usually no need to add the AUXSCORE card. In any Monte Carlo code this quantity is estimated by weighting particle fluences with energy and particle dependent coefficients (in this case the fluence-to-ambient-dose-equivalent conversion coefficients).
