conclusion
- GEANT is a useful tool for proton dosimetry
- with respect to nuclear interactions only secondary protons contribute significantly to the dose.
- this distribution is depth dependent, in contrast to PTRAN.
- for high beam energies the secondary protons contribute up to 10% of the total dose
- the delta electron ( > 10 keV) contribution to the dose is 20 %, but confined to max. 1.5 mm around the proton track.