[Henny]

Well speaking as a Nuc Med Tech..the Fluorine-18 in the sugar has a half life of 2 hours-so every 2 hours half of it is gone. It is considered completely gone after 10 half lives or 20 hours.
I would have the patients (including myself when I had my scans) rest in a lead lined room. This was only to keep the radiation exposure down for the techs who worked with it every day.
I also let family members who were adults and not pregnant in the resting room for the 1-2 hour uptake time. If there was a pregnant family member or children I had them wait in the regular waiting room. My physicist calculated that the person in the resting room with the patient would not have any measurable exposure.
And like everything in life we have to measure risks vs benefits. Sometimes a person would be so freaked out by having a scan they couldn't do it without their support person
Hope this helps

Henny