Developments in Accelerators Used for Particle Therapy

After the invention of the cyclotron by Ernest Lawrence and Robert Wilson's suggestion to use the Bragg peak in the depth-dose distribution of protons to apply a high radiation dose selectively into a tumor, the first patient was treated with energetic ions at the Bevatron in Berkeley in 1950. Since then cyclotrons and synchrotrons have been used to accelerate protons and ions for particle therapy. In the first 50 years of particle therapy many treatment facilities were located at laboratory based accelerators, but since 2000 the number of clinical facilities in a hospital based environment is increasing. An overview of developments in and related to the accelerators typically used in this medical application will be presented. This paper will concentrate on developments in cyclotrons and synchrotrons, since these two accelerator types are and are likely to remain the major accelerator types used for therapy in the coming years.