Further development of the preceding Gaussian-pencil-beam-model used for calculation of the in-water dose caused by clinical electron-beam irradiation

Purposes: We perform further development for our previous Gaussian-pencil-beam-model used calculating the electron dose in water under clinical electron-beam irradiation. The main purpose is to evaluate accurately parallel beam depth-doses at deep depths beyond about extrapolated range (Rp) an infinite field. Methods: Sets of field were reconstructed beams E=6, 12, and 18 MeV light Monte Carlo (eMC) datasets reported by Wieslander Knöös (2006), separating into direct direct-plus-indirect groups. then using each factor R_scale^OAD. Results conclusions: following results obtained comparing calculated depth (DD) off-axis (OAD) with eMC datasets: (i) revised Gaussian pencil model practical use without complicated correction factors; (ii) DD OAD are yielded effectively over wide ranges distances.