Fig 1.
Cross-section view of the simulated treatment head of the Siemens Artiste in Flat 6MV mode by the Geant4 toolkit.
Fig 2.
Validation of Monte Carlo simulation.
a) depth-dose curve and b) beam profile of the FFF beams, c) depth dose curve and d) beam profile of the Flat6MV beam, for 10×10 and 20×20 cm2 field sizes in voxels with dimension of 5×5×5 mm3 at depth of maximum dose. Points and stars under the green line show the absolute difference between measurement and calculation. The Monte Carlo statistical uncertainty for each point is between 1% to 1.6% which is not shown in figures.
Fig 3.
Validation of Monte Carlo simulation for 40×40 cm2 field size of FFF beams.
a) depth-dose curve and b) beam profile in voxels with dimension of 5×5×5 mm3 at depth of maximum dose. Points under the green line show the absolute difference between measurement and calculation. The Monte Carlo statistical uncertainty for each point is 1% to which is not shown in figures.
Fig 4.
Monte Carlo calculated depth-dose of FFF and Flat6MV beams.
For two field size of 10×10 and 20×20 cm2 in voxels with dimension of 5×5×5 mm3. Bars represent the uncertainty of calculation which are less than 1%.
Table 1.
Calculated D20/D10 in FFF and Flat6MV mode for two different field sizes.
Fig 5.
Comparison of Monte Carlo calculated beam profiles of FFF and Flat6MV.
For two field sizes at depth of 10 cm in voxels with dimension of 5×5×5 mm3. Bars represent the uncertainty of calculation which are between 1% and 1.6%.
Table 2.
Calculated penumbra for 10 and 20 cm field side at a depth of 10 cm.
Table 3.
Calculated unflatness of the FFF beam for 10, 20 and 40 cm square fields.
Table 4.
Calculated slope of the FFF beam for 10, 20 and 40 cm square fields.
Table 5.
Peak position and symmetry of simulated beam profiles for 10, 20 and 40 cm square fields at depth of 10 cm.
Table 6.
Comparison of the calculated relative surface and buildup dose of the FFF with the Flat6MV mode in voxels with dimension of 1×1×1 mm3.
Fig 6.
Comparison of Monte Carlo calculated photon energy fluence of FFF and Flat6MV.
For two field sizes at depth of 10 cm into intervals of 0.1 MeV.
Fig 7.
Comparison of the Monte Carlo calculated contaminant-electron energy fluence of FFF and Flat6MV.
For two field sizes at the surface of the water phantom into intervals of 0.1 MeV which normalized to their maximum value (100%).
Table 7.
The contribution of electron contamination dose in the total surface dose.
Fig 8.
Effect of the linac head components on the photon and electron spectrum.
a) photon. b) contaminant-electron fluence per incident primary electron at different stages of the beam line.
Table 8.
Comparison of calculated D20/D10 of FFF at various OAD with Flat6MV beams (20×20 cm2 field).
Fig 9.
Calculated photon energy fluence on the CAX and as a function of OAX. For FFF and Flat 6 MV with 20×20 cm2 field size.
Table 9.
Calculated photon mean energy of FFF beam on CAX and at difference OAX for 20×20 cm2 field size.
Table 10.
Photon mean energy at isocenter for square field sizes of 10 and 20 cm, overview of previous studies.