Ion beam cancer therapy: Fundamental aspects of the problem

We discuss different physical processes which may be responsible for biological damage induced by an ion beam propagating through living tissue. The creation of free radicals and an electron plasma, dissociative attachment of low-energy electrons, and local heating mechanisms are considered. Numerical estimates are performed for the case of carbon ion beams. We conclude that all three mechanisms are capable of inflicting single and double strand breaks in DNA molecules and thus can be responsible for the observed enhanced biological effectiveness of ion beams in cancer therapy