Simulation of the Final Focus and Collimator of the Electron Beam for VHEE Therapy (50-200 MeV) with Geant4 / TOPAS

As a summer student at CERN, I have been working in the compact Linear Collider group for 8 weeks. I worked with the Geant4 / TOPAS Monte Carlo simulation code. The Compact Linear Collider (CLIC) is a future electron-positron collider under study. It foresees e+e- collisions at center-of-mass energies ranging from a few hundred GeV up to 3 TeV. The CLIC study is an international collaboration hosted by CERN. In this paper, I will report the simulation of the final focus and collimator of the electron beam for VHEE Therapy, which could also be applicable to FLASH methodologies, which might be a major breakthrough in RT. Functional specifications include dose rates from 2 Gy/min to 100 Gy/sec, beam sizes with diameters from 0.5 mm to ≥ 10cm. High energies (> 140MeV ) would also be needed for therapy.