A VERSATILE PU-238 IRRADIATOR FOR RADIOBIOLOGICAL STUDIES WITH ALPHA-PARTICLES

A versatile irradiator has been constructed for in vitro irradiation of mammalian cells with alpha-particles of well-defined energy, LET, direction, dose and dose rate. It is based on approximately 1.2 x 10(9) Bq of Pu-238 (on a platinum disc) contained in a Hefilled chamber. In a standard configuration, monolayers of cells grown in 10 Hostaphan-based dishes are irradiated with 3.26+/-0.22 MeV alpha-particles (LET 121 keV mu-m-1) at selectable dose rates from approximately 2 Gymin-1 down to < 10(-4) Gymin-1 (i.e. fluence rates of 1x10(7) cm-2 min-1 to 3x10(2) cm-2 min-1). Single dishes can be irradiated at dose rates up to 24 Gymin-1 (fluence rate 1x10(8) cm-2 min-1). Incident energy and LET can be varied from 0.8 to 4.2 MeV and 266 to 102keV mu-m-1, respectively. The irradiator has full incubation and gassing facilities for protracted irradiations. The irradiator is particularly suitable for in vitro analytical studies of the biological effects of alpha-particles of energies and LETs similar to those which cells may receive in vivo from radionucleides such as radon and the actinides. It has been used successfully for investigations of a variety of alpha-particle-induced effects in different cell types irradiated either as attached monolayers or as very thin suspensions.