Analysis of biological effectiveness of heavy ions using two microdosimetric approaches

Experimental data on chromosome aberrations induced in GH2B2 mammalian cells by heavy ion beams were analysed using a hit-size effectiveness approach and a cellular track structure theory. The two approaches, based on rather incompatible premises, differ widely in their prediction of low level radiation risk from X ray or gamma ray fields, and in their predictions of RBE-LET dependences. Though for different reasons, both approaches suggest limitations in applying the present formulations of dose and of dose related RBE or Quality Factors in the low level region of interest in radiation protection. (author)