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ICRP: Free the Annals!

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Submitted by Yoshikazu Nishimura, National Institute of Radiological Sciences (NIRS)
   Commenting on behalf of the organisation
Document Dosimetric quantities
 
Generic Comments:
(1) The drastic change of the present radiation protection system will not well received, since the Commissionfs recommendations have implemented in 2000 in Japan. Stability of the principal recommendations is a very important factor for the societal acceptance of the recommendations.

Specific Comments:
(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 factorh. 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 effecth or gorganh names are requested to be specified.
(Absorbed dose@Ë@Gy @or@J kg-1)
RBE-weighted dose@Ë@Gy-Eqibiological effect etc.j
Ex.@F@Gy-Eq(cell killing), Gy-Eq(mutation) Gy-Eq, etc.
Radiation-weighted dose@Ë@Sv(organ)
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.