My husband had a stress test in the hospital a couple of weeks ago, and it is quite freaky. They bring out an actual lead-lined box with all kinds of radioactive symbols on it. They open it up, and the syringe is inside, that they then inject you with. Boy do you feel safe at that point!!!
All that stuff is to protect the technologists, who may do 20 injections like that every day, day after day, year after year.
The radiation risk to any individual patient, or their family, is unmeasurably small. Your husband got the equivalent of a few chest X-rays, and you probably got more radiation on your last airplane trip.
-ccm