LET distributions form neutron fields interacting with tissue have been studied extensively. Proton recoils form neutron of energy 10 KeV to 1 MeV have a maximum LET of about 85-90 KeV/m. This maximum LET occurs near the peak of the Bragg Curve. The LET of proton recoil from neutrons with energies above 1 MeV gradually decreased in such a manner that at the neutron energy of 20 MeV the LET has decreased to 5 KeV/m.