10 C.F.R. § 35.2075 – Records of the release of individuals containing unsealed byproduct material or implants containing byproduct material.

(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.
(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).
(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.