An alternative method for the release criteria and calculation of the total dose equivalent to another individual from a patient treated with a therapeutic dose of 131I.

The Nuclear Regulatory Commission's Regulatory Guide 8.39, "Release of Patients Administered Radioactive Materials," permits licensees to authorize the release of patients treated with 131I [(T 1/2)p = 8.04 d] if the total dose equivalent to another individual from the released individual is not likely to exceed 5 millisieverts (0.5 rem). This paper guides the reader through the derivation of an easy-to-use formula that demonstrates how to calculate the total dose equivalent, using patient-specific parameters that an individual may receive from a patient who has been administered a therapeutic dose of 131I, as compared to the NRC's Reg. Guide 8.39 (see Appendix A). Patient-specific parameters include the individual thyroidal uptake, the patient's physical dimensions, attenuation of radiation by body tissues, buildup of secondary photons, whole body and thyroid retention functions as well as the distance and time the patient is around others. This paper also demonstrates how to calculate an inpatient's discharge time, so that the patient will not expose other individuals above the desired total dose equivalent set by the Radiation Safety Officer (RSO).