(1) The drastic change of the present radiation protection system will not well received, since the Commissionfs recommendations have implemented in 2000 in Japan. Stability of the principal recommendations is a very important factor for the societal acceptance of the recommendations.
(1) Regarding the radiation weighting factor wR, single values are given for protons and heavy ions whereas that for neutrons is fully defined as a function of energy based on the discussion about qE which is given as a function of LET. The same approach should be taken for these radiations so that we can have energy-dependent wR values (functions) for protons and heavy ions as well.
In regard to heavy ions, it is stated that gFor applications in space where these particles contribute significantly to the total dose in the human body, a more realistic approach may be chosen based on the calculation of a mean quality factorh. In a spacecraft, however, astronauts are exposed to neutrons as well in addition to heavy charged particles. Because we have to determine an effective dose as a sum of the doses from all these particles, definition and precision of weighting should be given in the same way. Thus it is strongly requested to define energy-dependent wR values for protons and heavy ions, as neutrons.
(2) The following units are requested to define for the new quantities for clarification as well as not leading misunderstanding; in the blankets gbiological effecth or gorganh names are requested to be specified.
(Absorbed dose@Ë@Gy @or@J kg-1)
RBE-weighted dose@Ë@Gy-Eqibiological effect etc.j
Ex.@F@Gy-Eq(cell killing), Gy-Eq(mutation) Gy-Eq, etc.
Ex.F@Sv(skin), Sv(lens), Sv(ICRU sphere), etc.
Effective dose @Ë@Sv
(3) More detail description or references are required about RBE for tissue reactions since they are used in the calculation for RBE-weighted dose.@
(4) Regarding the radiation weighting factors for neutron, it is described that in the energy range above 1 MeV all existing experimental data either on animals or on cells show a strong decrease of RBE with increasing neutron energy. Citation of the references of existing experimental data is required for the change of radiation weighting factors for higher energy.