tokens: The following protection quantities shall be used when relating the basic physical parameters to biological systems : 1 . The mean organ absorbed dose , DT 2 . The relative biological effectiveness , RBE 3 . The radiation weighting factor , wR 4 . The organ equivalent dose , HT 5 . The tissue weighting factor , wT , and 6 . The effective dose , E. NOTE 1 Protection quantities are defined by the International Commission on Radiobiological Protection ( ICRP ) . NOTE 2 The mean organ dose , organ equivalent dose , and effective dose are not directly measurable , but are essential for assessing risk due to a radiation environment .