Why are people placed in isolation when they have thyroid cancer?

Radiation Treatment: Treatment for the most common kinds of thyroid cancer may include swallowing a capsule with radioactive iodine. Much of the radiation from this goes to any remaining thyroid cells after surgery. Some leaves the body, however, and could affect anyone near them. Since others do not benefit from this radiation, we try to keep their exposure as low as possible. Keep your distance for 3-7 days.

Not really: There are radiation precautions if you receive radioactive iodine after surgery (see:http://www.Radiologyinfo.Org/en/info.Cfm?Pg=radioiodine) things like - not sharing a toilet for a few days, not sharing eating utensils, sleep alone and avoiding intimate contact for 3-4 days. (brief contact, like handshaking or a quick hug are ok). A bit of a hassle for a few days, but not really isolation.