Water radiolysis with thermal neutrons, fast neutrons and contamination γ rays in the accelerator based thermal neutron field: Time dependence of hydroxyl radical yields

Radiation chemical yields (G value) of OH radicals created in the accelerator-based neutron field are evaluated using coumarin-3-carboxilic acid (C3CA) solution to understand the role of the indirect action induced by radiations emitted as a result of B-10(n,alpha)Li-7 reactions for boron neutron capture therapy. The G values for ionizing radiations emitted as a result of B-10(n,alpha)Li-7 reactions, the contamination (ionizing) radiations (i.e., fast neutrons and gamma rays) in the accelerator-based neutron field are discriminately assessed. We have followed the recombination process of OH radicals by adjusting the concentration of C3CA solution from 0.5 to 20 mM. The G values for ionizing radiations emitted as a result of B-10(n,alpha)Li-7 reactions are the lowest ones. This finding indicates that the indirect action induced by B-10(n,alpha)Li-7 reactions is not effective to kill tissues. In comparison to this, a significant influence would be expected by the contamination (ionizing) radiations not only on cancer tissues but also on healthy tissues.