Figure 7.

Comparison of measured (markers) and TOPAS (dashed lines) FSF dependence along beam path in air and in water after the range shifter for energies of 115 MeV (a) and 225 MeV (b) with the water phantom surface placed at an air gap of 195 mm, where the left side of the perpendicular dashed line is in air and the right side is in water (purple and “o” for 40 × 40 mm field size; green and “$\mathrm{\Delta }$” for 48 × 48 mm; cyan and “+” for 96 × 96 mm field size; black and “*” for 200 × 200 mm field size).