11.2.2 Protection quantities

11.2.2.1 General

a. The following protection quantities shall be used when relating the basic physical parameters to biological systems:

1. The mean organ absorbed dose, D_T

2. The relative biological effectiveness, RBE

3. The radiation weighting factor, w_R

4. The organ equivalent dose, H_T

5. The tissue weighting factor, w_T, 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.

11.2.2.2 Value of the radiation weighting factor, w_R

a. The values of the radiation weighting factor shall be as specified in Table 11‑1.

b. Values for the radiation weighting factor of particles not specified in Table 11 shall be derived by dividing the ambient dose equivalent for the particle H*(10) by the dose at 10 mm depth in the ICRU sphere [12].

NOTE 1 The radiation weighting factor, w_R, accounts for the different levels of biological effects resulting from different particle types, although they can produce the same mean organ dose. For further discussion on w_R see ECSS-E-HB-10-12 Section 10.2.2.

NOTE 2 The values in Table 11‑1 are from ICRP-60 [11], and are defined and maintained by the ICRP. The users are encouraged to consult the ICRP for the more recent updates.