Design of a novel linear accelerator for carbon ion therapy

Hadron therapy has been first proposed in 1946 by Robert Wilson as an advanced form of radiotherapy. Hadrons, such as protons and light ions, release the largest part of their energy in a narrow space range, called Bragg peak, allowing to target the tumor cells more precisely than photon beams. Despite this advantage, the number of proton and carbon ion therapy centers is still small compared to conventional radiotherapy. One of the reasons for this disparity can be found in the treatment costs of hadron therapy, which is three to four times higher than for conventional radiotherapy, due to the larger and more complex accelerators needed, which imply typically the construction of entirely new buildings, with the associated medical and technical personnel. The limited availability of hadron therapy has also consequences on the number of patients that can be enrolled in clinical trials, that are necessary to assess the effective clinical advantages with respect to other, less costly, therapies. The main goal in the development of hadron therapy technology is to reduce as much as possible the cost of the machines, by proposing smaller and more efficient solutions, easing the access to this treatment. Proton therapy has already moved in this direction, bringing the accelerator technology to industrialization and offering compact turn-key solutions that reduce the cost gap with respect to radiotherapy. The few carbon ion centers worldwide, on the contrary, are still based on bespoke solutions: the development of carbon ion machines is still carried out, in most of the cases, in the framework of research laboratories and is far from the industrialization step needed to improve the accessibility to the service. Synchrotrons are the only technology used in carbon ion therapy centers. However, in the past years, the idea of using linear accelerators has been developed, initially for proton therapy, due to the advantages it would bring in terms of costs and therapeutic beam quality. At present, there are worldwide two medical proton linacs being commissioned, while linacs for carbon ions are still at a conceptual stage in a handful of research centers. The general purpose of this thesis work is to propose the beam dynamics design of a 3 GHz linear accelerator for carbon ion therapy from the pre-injector, based on the pioneering work done at the European Organization fro Nuclear Research (CERN) on a proton machine, to the very end of the linac.