Optimization of Dual Scattering Foil for 6 to 20 MeV Electron Beam Radiotherapy

From last 50 years, electron beam therapy has an important radiation therapy modality. The electron beam from the LINAC is of size ∼ 2 mm, whereas the size required for actual treatment is usually larger than 2 × 2 cm up to 25 × 25 cm at the isocenter. In the present work, it is proposed to use dual scattering foil system for production of clinical electron beam. The foils for 6 to 20 MeV electrons were optimized using the Monte Carlo based FLUKA code. The material composition, thickness of primary foil, Gaussian width and height of secondary foil were optimized such that it should meet the design parameters such as dose at isocenter, beam uniformity, admixture of bremsstrahlung, etc. In conclusion, the primary scattering foil has been optimized with high Z element (Ta) having uniform thickness, whereas the secondary foil has been optimized with low Z element (Al) having Gaussian shape.