Fig. 4.

Shown (a) $\overline{l}$ and energy deposition percentage depth dose normalized to its value at the Bragg peak (PDD) (b) energy deposition modeled in SF, ${\epsilon }_D=\overline{{\epsilon }^2}/\overline{\epsilon }$ and (c) four types of LET averaging used in this work vs. depth for pencil beams of protons with nominal energies, 80, 90, 100, 110, and 120 MeV. The letters D,d,t and 1D, denote lineal-energy averaged LET, $y_D=\overline{y^2}/\overline{y}$, dose-averaged LET, LET_d, and two types of track-averaged LETs, ${\mathrm{LET}}_t=\overline{\epsilon }/\overline{l}$ and $y_{1D}={\epsilon }_D/\overline{l}$ respectively.