Operational Quantities for External Radiation Exposure

Draft document: Operational Quantities for External Radiation Exposure
Submitted by Tadahiro Kurosawa, National Metrology Institute of Japan, AIST
Commenting on behalf of the organisation

     The operational quantities are quantities to be measured, and these definitions shall be stable. The new operational quantities are still unstable because the tissue weighting factor will change in a certain period. The discussion with CIPM (Comité International des Poids et Mesures) should be done before the report is published.

     Even though the difference of conversion coefficients is small, calibration laboratories have to do much work for applying new operational quantities. The calibration laboratories have to evaluate the reference radiation fields more precisely in order not to increase the uncertainty of the measurement.

     In the case of the beta dosimetry, the new conversion factors could not be used because the primary standards are absorbed dose to tissue at the depth of 0.07 mm or 3 mm for the skin and eye, respectively. The definitions are completely different between the primary standards and the proposed definitions of dose for skin and eye.  All calibration laboratories will be required the electron-photon transport calculation in the full-modeled geometry when the new definitions come into effect. The energy and incident angle distributions of the electron fluence in beta-particle radiation fields are difficult to be obtained. In the case of the beta dosimetry, therefore, the sentence from 1236 to 1238 is not true.