Radiation safety is an essential component in the treatment of human patients with thyroid diseases by radioiodine (I-131). This is true of human patients, as well as the cats and dogs that we treat with radioiodine.
The American Thyroid Association (ATA) created a task force to develop recommendations that would inform medical professionals about attainment of radiation safety for patients, family members, and the public. The task force was constituted so as to obtain advice, experience, and methods from relevant medical specialties and disciplines.
This publications from the ATA Taskforce on Radiation Safety details a summary of their conclusions and recommendations, depending on the dose of radioiodine administered to the patients.
As you can see, the guidelines recommended for human patients are much less stringent that we have to follow for our feline and canine patients treated with radioiodine!
Sisson TA, Freitas J, McDougall IR, Dauer LT, Hurley JR, Brierley JD, Edinboro CH, Rosenthal D, Thomas MJ, Wexler JA, Asamoah E, Avram AM, Milas M, Greenlee C. Radiation safety in the treatment of patients with thyroid diseases by radioiodine 131-I: practice recommendations of the American Thyroid Association.Thyroid 2011; 21(4):335-346.