I had one a few years back --and I was in the middle of training for a marathon. A normal stress test showed exertional PVCs so they ordered a nuclear. Because I was in training and it was a teaching hospital the room was crowded with med students wanting to see a marathoner on a treadmill test. Or maybe an accident waiting to happen. Getting the nuclear injection wasn't bad. Weird part was being strapped to a table immediately after pushing to exhaustion. Sweating like crazy and breathing hard while gyrating around with a giant sensor all around me. Being in a hospital you should be quite safe no matte what happens. That's what they told me.