II.17 — Physics and accelerators for particle therapy

At the Paul Scherer Institute (PSI) radiation therapy is performed by means of proton beams. Proton therapy is one of the particle therapies, in which energetic ions (mostly protons and carbon ions) are used to treat cancer patient by irradiating the tumor with high precision. At PSI the radiation dose is applied by a proton beam of max 250 MeV. In this chapter, the interactions of energetic ions with matter (tissue) and the way particle therapy is applied are discussed, followed by a description of the PSI’s medical proton cyclotron and the treatment rooms in which the dose is applied to the patient.