Abstract
Currently protons and carbon ions are the only heavy charged particles used for radiotherapy. There is particular interest in the use of helium ions for therapy, as they present physical dose and clinical advantages over carbon ions and protons. In this thesis, a Fixed Field Alternating Gradient (FFAG) approach has been developed for helium ion therapy, which has never been explored before. Two non scaling FFAG accelerators are designed, accelerating He2+ ions to 900 MeV, the necessary energy to reach 30cm depth in tissue.Initial steps have characterised the beam optics in order to achieve isochronous stable equilibrium orbits over the design energy range described above, whilst maintaining the working point with few resonance crossings. The desired energy range of the machine is split across two stages, of which both were successfully optimised to have a time of flight to within 1% of each other. A common operating RF frequency has been identified, and the RF parameters that are currently achievable were assessed and suitability for this design investigated. Having successfully chosen realistic RF parameters, a beam has been accelerated and it has been demonstrated that there is a sufficient dynamic aperture and extraction is possible.
The feasibility of a nsFFAG accelerator for the purposes of helium therapy has been successfully investigated, and a helium ion beam was successfully accelerated through simulation from 1 MeV to 900 MeV across two stages, using fixed frequency acceleration. The design is compact, though splitting the design into two machines has increased the footprint. However, the first stage has the potential to be used as a standalone facility for research and shallow tumours, and the accelerator could likely fit in a current radiotherapy bunker. Further work will need in depth design studies to model the magnetic field and RF cavity designs, to verify the design.
| Date of Award | 26 May 2020 |
|---|---|
| Original language | English |
| Supervisor | Rob Edgecock (Main Supervisor) & Susan Kilcoyne (Co-Supervisor) |