Microdosimetric Investigations for Neutron Therapy

Abstract

Abstract Microdosimetric investigations are commonly performed to determine the radiation quality of neutron sources applied in radiotherapy. At the DT neutron therapy unit of the University Hospital at Hamburg-Eppendorf, microdosimetric spectra were measured with spherical proportional counters at different positions in a solid tissue-equivalent phantom. Counters with different types of wall materials were used to analyse the spectra with respect to the relative contribution of the different types of charged particles to the total absorbed dose. An iterative procedure usually applied for activation analysis was modified to evaluate RBEs relative to lineal energy functions from radiobiological and microdosimetric data. A set of RBE values obtained with the Withers system at various neutron sources was used together with the corresponding microdosimetric spectra. A second set of data resulting from an earlier biological and microdosimetric intercomparison is used to show the sensitivity of the unfolding procedure to changes in the data base.