Low ionizing event rate

Hi,

you can definitively calculate dose maps. That is fine. Depending on your geometry, you may need to reduce the cut and fix a maximum step to obtain more accurate results in terms of energy deposition.
What is not possible to do is to calculate the number of ionizations that produces that dose with Condensed History Approach. The edep is associated with the pre-step point and many real ionization events are condensed in a single step. You can count the number of ionizations using a track structure code (e.g. geant4-DNA). You may look into the TS model for silicon (here I make the assumption you use silicon) which are available for electrons. The context is different, but this concept is explained in Lazarakis et al, https://ro.uow.edu.au/cgi/viewcontent.cgi?article=2347&context=eispapers1
Again you can calculate dose maps, but not the number of ionizations associated with that dose. You can do it by a software point of view, but this does not represent the real number of ionization events, which will be a lot higher.