[en] The contributions of a poster session from a clinical radiotherapy conference are discussed. The contributions were concerned with radiation quality, RBE measurements, dosimetry and neutron spectra with particular respect to the biologically and clinically significant description of the radiation quality of fast neutron and high LET radiations. The usefulness of a quantity, y*, describing the saturation corrected dose average lineal energy was discussed. It was concluded that microdosimetric models need to be refined with regard to a more precise description of radiobiological mechanisms. In clinical radiation, a physical quantity describing radiation quality remains an unsolved problem. (U.K.)