Changes in RBE of 14-MeV (d + T) neutrons for V79 cells irradiated in air and in a phantom: is RBE enhanced near the surface?
The measured values of RBE as function of dose per fraction within the phantom is consistent with the energy of the neutron beam. The increased RBE free in air, however, is greater than expected from microdosimetric parameters of the beam and may be due to slow recoil protons produced by interaction of multiply scattered neutrons or to an increased contribution of alpha particles from C(n, alpha) reactions near the surface. An enhanced RBE in subcutaneous layers of skin combined with an increase in RBE at low doses per fraction outside the target volume could potentially have significant consequences for normal tissue reactions in radiotherapy patients treated with fast neutrons.
Under the conditions of this study, puncturing of the peripheral nerves and apparent intraneural injection during axillary plexus block did not lead to a neurologic injury.