Not really. Not really.
Yes. There are no radiation safety measurements or precautions to follow after you have a nuclear cardiac stress test using tc99m, thallium, or other diagnostic isotope. You can be around babys and pregnant women. You should not have the test if you are pregnant. If you are breastfeeding you should stop (pump and discard) during the first 12-24 hours after the study (depending on the dose received).
Small exposure. The doses of radiopharmaceuticals used for these scans are usually relatively low dose. However thallium (half life 2.7 days) gives more radiation than technetium sestamibi (half life 6 hrs).Radiation reduction depends mainly on two factors time and distance. If you do not stay close to child for prolonged time then radiation exposure is reduced.Growing children more sensitive to radiation.
If you were a hazard. They would be required to keep you until you were not. The usual isotope is thallium, which emits imaging compatable x-rays and photons. Always safest to avoid, next best ie distance, and last limit time that any one is proximate. Check the clinica for their precise nuclear regulatory commission guidelines on this. I would not worry.