Development of NbTi CCT superconducting magnet technology for radiotherapy applications

Start-of-the-art particle radiotherapy facilities benefit from superconducting (SC) magnet technology to allow a significant reduction in their size. This is particularly important in the next generation of ion therapy systems that will deliver carbon-ion beams to patients and will significantly expand the range of treatments offered to patients; present-generation particle sources can be reduced from c.80m to c25m in size by using superconducting magnets utilizing industrially-proven niobium-titanium cable technology delivering fields around 5T. However, no suitable design of superconducting prototype magnet has yet been demonstrated.

This project aims to develop the science and engineering of a novel canted-cosine-theta (CCT) combined-function (CF) dipole in a curved cryostat with large (>80mm) central aperture. The first aim of this study will be applied to a compact synchrotron utilizing a highly-novel hybrid rapid cycling design that has not been previously proposed; a rapid-cycling compact C6+ synchrotron would deliver a step change in therapy by delivering both high dose rates and rapid, precise variation of the dose delivery at different treatment depths in patients. The development of a suitable CF magnet is the key enabler for this project, which would deliver the next-generation of ion therapy system to be applied in Europe, and which has been identified in the UK as a future needed treatment facility. Other applications include use of similar technology for the final dose delivery, and for other applications in particle sources for x-ray imaging science.

Working with our project partners in the CERN superconducting magnet design group and at STFC Daresbury Laboratory/University of Melbourne, we will use our previous experience of CCT design to develop a curved (90-degree) dipole/quadrupole magnet with alternating-gradient focusing in a single cryo-cooled rotating cryostat; this has not previously been done. CERN collaboration will provide their extensive engineering knowledge of winding and assembling similar magnet systems, and we intend to prototype a candidate magnet during the PhD duration. Later options include the use of alternative conductor materials such as NbSn and REBCO to achieve larger aperture magnets.

There is significant scope to translate the technology into UK industry. Several UK companies have existing SC production in areas such as MRI magnet systems, and we will explore partnerships with suitable suppliers to look forward to later construction of a UK ion treatment facility.