Radiation quality studies of a fast neutron therapy beam

As part of a neutron therapy project a microdosimetric investigation of the therapy facility is being carried out and first results are reported. Standard techniques of experimental microdosimetry are being used. It is shown that such methods yield information of particular relevance for a therapeutic unit such as gamma contamination of the neutron beam and the influence of collimator and phantom scattering on the radiation quality. Apart from this type of data the measured microdosimetric spectra provide the data required to employ the Dual Radiation Theory for describing radiation effects. Radiobiological experiments for describing radiation effects. Radiobiological experiments with HeLa cells complete the radiation quality study. Special attention is directed towards overcoming the problems of in vitro measurements at low doses and preliminary results are given