10 CFR §35.2075

1. (a)A licensee shall retain a record of the basis for authorizing the release of an individual in accordance with § 35.75, if the total effective dose equivalent is calculated by—
   1. (1)Using the retained activity rather than the activity administered;
   2. (2)Using an occupancy factor less than 0.25 at 1 meter;
   3. (3)Using the biological or effective half-life; or
   4. (4)Considering the shielding by tissue.
2. (b)A licensee shall retain a record that the instructions required by § 35.75(b) were provided to a breast-feeding female if the radiation dose to the infant or child from continued breast-feeding could result in a total effective dose equivalent exceeding 5 mSv (0.5 rem).
3. (c)The records required by paragraphs (a) and (b) of this section must be retained for 3 years after the date of release of the individual.