Yes Larry, I'm pretty sure there is a "low tech" proton treatment. I had the same thing almost three years ago for the last several treatments. I recall the Radiation Oncologist specifically telling me about the different type of radiation and that it had very controllable depth of penetration. The difference here is that the areas to be treated were defined by blocks of Lead not by computer controlled "Fingers".

Proton charged particles, as Gary said, have a very predictable penetration depth based upon the energy settings of the system. Lower energy (power), lower depth of penetration, Higher power, greater depth of penetration.

I AM EDITING MY POST. upon more reading, I realize that it is UNLIKELY that my treatments included PROTON radiation, so I'm going to have to call my RAD ONC DOC and ask what it was he did at the end of my treatments ???