Abstract
The RBE values for neutrons vary to a wide range and the influencing factors have been discussed. The relevance of cytogenetic end points as signature of the past neutron exposure, and the importance of cosmic component of neutron have been explored. The neutron-induced multiple damage sites are understood as more mutagenic, carcinogenic and lead to complex chromosome aberrations. Low energy neutrons (0.2- 2 MeV) are the principal concern in biodosimetry. They exhibit little or no β component and also independent of dose-rate effect. The review also emphasizes the wide range of RBE need to be considered for neutrons. Such knowledge may be helpful to draw guidelines to set dose limit for radiation workers under specific field and to devise effective neutron therapy. Also to make high-altitude travels and space voyages safer for human beings.
Highlights
Study of the relative biological effectiveness (RBE) of neutrons is important for risk assessment and in understanding the basic mechanisms of radiation biology
T-lymphocytes can readily be induced to grow outside the body by adding phytohaemagglutinin and the cell growth can be arrested at appropriate stage of the cell division to make chromosome analysis feasible under light microscope
Even for the 13.6 MeV neutrons the RBEM exceeded 10. These results reveal that RBE of neutron varies with energy and dissimilar between different types of asymmetric chromosome aberration (CA)
Summary
Other than recoil proton, energy >2 MeV the quality factor (Q) for neutrons (Table 1) of different energies. The CA induced by 25 keV neutrons in human lymphocytes gave linear dose response curve of 1.1 dicentrics/cell/Gy (Aghamohammadi et al, 1989). Pandita and Geard (1996) recorded the dose response for dicentrics was always linear for the energy range between 0.22 and 13.6 MeV of monoenergetic neutrons (RARAF, Columbia). Monoenergetic neutrons ranging from 0.23 to 13.7 MeV was used at low doses 0.05 to 1.47 Gy. RBE of neutrons over different response (Y=αD) for CA was obtained for all monoenergetic neutrons and for 137Cs-γ-rays. Even for the 13.6 MeV neutrons the RBEM exceeded 10 These results reveal that RBE of neutron varies with energy and dissimilar between different types of asymmetric CA. A linear response was recorded among energy ranges, some are more effective at some type of aberration induction per unit absorbed dose. 3.9 Tateno et al, 1996 differences in RBE were breaks demonstrated
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