Rem
Rem means a measure of the dose of any ionizing radiation to body tissue in terms of its estimated biological effect relative to a dose of 1 roentgen (r) of X-rays (1 millirem (mrem) = 0.001 rem). The relation of the rem to other dose units depends upon the biological effect under consideration and upon the conditions for irradiation. Each of the following is considered to be equivalent to a dose of 1 rem:
(i) A dose of 1 roentgen due to X- or gamma radiation;
(ii) A dose of 1 rad due to X-, gamma, or beta radiation;
(iii) A dose of 0.1 rad due to neutrons or high energy protons;
(iv) A dose of 0.05 rad due to particles heavier than protons and with sufficient energy to reach the lens of the eye;
(v) If it is more convenient to measure the neutron flux, or equivalent, than to determine the neutron dose in rads, as provided in paragraph (a)(7)(iii) of this section, 1 rem of neutron radiation may, for purposes of the provisions in this section be assumed to be equivalent to 14 million neutrons per square centimeter incident upon the body; or, if there is sufficient information to estimate with reasonable accuracy the approximate distribution in energy of the neutrons, the incident number of neutrons per square centimeter equivalent to 1 rem may be estimated from Table G–17:
(i) A dose of 1 roentgen due to X- or gamma radiation;
(ii) A dose of 1 rad due to X-, gamma, or beta radiation;
(iii) A dose of 0.1 rad due to neutrons or high energy protons;
(iv) A dose of 0.05 rad due to particles heavier than protons and with sufficient energy to reach the lens of the eye;
(v) If it is more convenient to measure the neutron flux, or equivalent, than to determine the neutron dose in rads, as provided in paragraph (a)(7)(iii) of this section, 1 rem of neutron radiation may, for purposes of the provisions in this section be assumed to be equivalent to 14 million neutrons per square centimeter incident upon the body; or, if there is sufficient information to estimate with reasonable accuracy the approximate distribution in energy of the neutrons, the incident number of neutrons per square centimeter equivalent to 1 rem may be estimated from Table G–17: