The DOSE Step: Charged Particle Interactions
All the photon interactions release some energy to recoil charged particles
including photoelectrons, Compton electrons, and electron-positron pairs, which are
ultimately responsible for energy deposition in tissue. The charged particles are launched
with a spectrum of initial energies and directions. These particles then slow down through
multiple Coulomb collisions, which deposit energy locally along the particle track and
occasional radiative bremsstrahlung events that carry energy remotely away from the
charged particle track. To include only local energy deposition, the mass collisional
stopping power is thus more relevant to the energy deposited locally along the path of a
charged particle: