DNA physics for photons

Physics Lists
1

Why is DNA physics only used to calculate water?

If I calculate the mixture of platinum in water, Will the error be significant?
Very interesting, but the result is different between water and mixture of platinum in water.

Thanks everyone!

1 Like
2

The physics models for photons are not “specialised” for Geant4-DNA but are the same physics models of the Condensed Approach.

For electrons, protons, alpha particles, etc, the Geant4-DNA physics models are only available in water and will not work in platinum.

You have two choices:

  1. Model the mixture and use Livermore physics list down to 10 eV.
  2. model the Pt nanoparticles as G4Orbs and activate Livermore down to 10 eV in platinum while having G4DNA physics list in the biological medium. This is definitively the most accurate approach as it takes into account the sizes/distribution of the Pt nanoparticles in the medium.
3

Thanks for the useful information!

I do not use nanoparticles and this cases platinum atoms are used.
Is mixture of platinum and water atoms.

I don’t understand how I can use DNA-physics for water and livermore-physics for platinum atoms at the same time.

So,

  1. Model the mixture and use Livermore physics list down to 10 eV.

Thank you!

4

-to look how to switch the Geant4-DNA in specific regions, you may look at examples/extended/medical/dna/dnaphysics

-If you have atoms and not aggregates, yes, I think to have a mixture material sounds good (at least to me).

Cheers

5

Yes I know this example, it has already tested.
But physics can be declared there only for the region, for example: World (water) - is DNA_OPT3
if World is WATER+platinum atoms.
How to specify physics for a particular material?
i.e In World region (mat -WATER+platinum atoms):

  • Water - is DNA_OPT3
  • Platinum - is Livermore physics

Sorry…My judgment may be wrong…

6

It is not possible to have DNA_OPT3 if the medium is a mixture of different materials. It only works if the material if G4_WATER.