This paper presents the first demonstration of deeply penetrating dose delivery using focused very high energy electron (VHEE) beams using quadrupole magnets in Monte Carlo simulations. We show that the focal point is readily modified by linearly changing the quadrupole magnet strength only. We also present a weighted sum of focused electron beams to form a spread-out electron peak (SOEP) over a target region. This has a significantly reduced entrance dose compared to a proton-based spread-out Bragg peak (SOBP). Very high energy electron (VHEE) beams are an exciting prospect in external beam radiotherapy. VHEEs are less sensitive to inhomogeneities than proton and photon beams, have a deep dose reach and could potentially be used to deliver FLASH radiotherapy. The dose distributions of unfocused VHEE produce high entrance and exit doses compared to other radiotherapy modalities unless focusing is employed, and in this case the entrance dose is considerably improved over existing radiations. We have investigated both symmetric and asymmetric focusing as well as focusing with a range of beam energies.
Very High Energy Electrons (VHEEs) are a promising alternative to conventional radiotherapy due to their highly penetratingnature and their applicability as a modality for FLASH (ultra-high dose rate) radiotherapy. The dose distributions due to VHEE need to be optimised; one option is through the use of quadrupole magnets to focus the beam, reducing the dose to healthy tissue and allowing for targeted dose delivery at conventional or FLASH dose rates. This paper presents the first targeted area of focused VHEE dose delivery in air and a water phantom, obtained using six quadrupoles at fixed field strengths and adjusted by changing only the strength of one quadrupole and the beam charge at the CLEAR (CERN Linear Electron Accelerator forResearch) facility for beam energies >200 MeV. Experimental results have been verified with Monte Carlo modelling. This targeted dose delivery method in the form of a ’Spread-Out Electron Peak’ (SOEP), analogous to the Spread-Out Bragg Peak(SOBP) for protons, could potentially be used in future (FLASH) VHEE treatments. As a step towards this, the effect of the vacuum beampipe aperture size and spacings between quadrupoles were explored and optimised in Monte Carlo simulations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.