I had nuclear imaging in attempt to donate to my husband. I didn't have any problems with my test (other than failing it).
I would suggest you call them back and ask for a more detailed explanation of what happened for your own peace of mind.
Health care professionals tend to forget that the general public doesn't understand their jargon.
Aleta
PS. No fear of the world ending. We humans will eventually make the earth uninhabitable, but that is not likely to happen this year, or next.