I was told that I didn't have to follow any restrictions after the diagnostic dose of I-123 other than "not sleeping in the same bed" as my daughter. The treatment dose of I-131 is the one where you have to be isolated. My treatment week looked something like this:
Monday: Blood/Urine tests
Tuesday: Off
Wednesday: Thyrogen Shot #1
Thursday: Thyrogen Shot #2 & tracer dose of I-123
Friday: Full Body Scan & treatment dose of I-131
If you are just having a scan for follow-up then they will probably give you the tracer dose and the following day you'll have your scan. If anything comes up during the scan they will probably administer RAI that day...
Well, there is a small dose scan and then there is the large ablation dose we think of as RAI. Both you have to wait to be scanned after the dosage takes effect. Only one, the ablation dose, I believe, requires you to be isolated. But I've only had the one (huge does) thus far, so I'm not versed on the follow up protocol yet...