Micronuclei induced by fast neutrons versus 60Co gamma-rays in XXXX peripheral blood lymphocytes.

@entity1 @entity4523 @entity734
Here we compared the effectiveness of neutrons (<E> = 5.5 MeV) versus 60Co gamma-rays in producing @entity4523 ( @entity4523 ) in @entity1 lymphocytes. To obtain dose-response data, blood samples of six donors were irradiated with doses ranging from 0.1 to 5 Gy for gamma-rays and 0.1-3 Gy for neutrons. A linear @entity734 of @entity4523 yield with dose was found for fast neutrons while for gamma-rays a nonlinear @entity734 existed. For both radiation qualities no significant interindividual differences were found. Derived relative biological effectiveness values decreased with increasing dose. The @entity4523 frequency distributions were overdispersed with respect to the Poisson distribution, with neutrons showing higher dispersion values than with gamma-rays. To compare the repair kinetics of both radiation qualities split-dose experiments were performed. A dose of 4 Gy gamma-rays (3 Gy neutrons) was delivered either as a single exposure or in two equal fractions separated by time intervals ranging from 30 min to 10 h (30 min to 7 h for neutrons). The data showed for gamma-rays a significant decline (30% +/- 10%) in @entity4523 yield with interfraction time due to repair of DNA damage. This repair is a continuous process starting almost immediately after the first of the two doses and lasting 3-5 h. For fast neutrons no decline was observed indicating irreparable damage.
