  Almost since the time of the discovery of the neutron more than 70 years ago,
efforts have been made to understand the effects of neutron radiation on tissue
and, eventually, to use neutrons for cancer treatment. In contrast to charged
particle or photon radiations which directly lead to release of electrons,
neutrons interact with the nucleus and induce emission of several different
types of charged particles such as protons, alpha particles or heavier ions.
Therefore, a fundamental understanding of the neutron-nucleus interaction is
necessary for dose calculations and treatment planning with the needed
accuracy. We will discuss the concepts of dose and kerma, neutron-nucleus
interactions and have a brief look at nuclear data needs and experimental
facilities and set-ups where such data are measured.
