ABSTRACT

Ion beam therapy is a rapidly emerging treatment modality that makes use of the favorable properties of ion interaction with tissue. Additional processes that influence the exact shape of the three-dimensional (3D) dose distribution of an ion beam are energy loss straggling, affecting the longitudinal Bragg peak width multiple Coulomb scattering, affecting the lateral beam spread and nuclear interactions, which modify the particle energy flounce spectrum. The information resulting from all earlier-mentioned measurements enables a complete 3D dosimetric description of pencil-like beams when entering a water medium placed at an arbitrary position in the treatment room. Modern beam scanning delivery can considerably reduce neutron production, by minimizing the amount of material encountered by the beam on its path to the patient. Radiation therapy with proton and carbon ion beams is a rapidly emerging modality that promises superior selectivity of the dose deposited to the tumor, with excellent sparing of healthy tissue.