I had my Petscan 2 weeks ago and was worried but in all honesty it was fine. Nothing to worry about. I like yourself was worrried but I worried over nowt. I was super bored as they give you the radiation tracer and you are left in a room all alone for 90 minutes for the tracer to do it's job. Boredom was the biggest piss off for me. My phone went flat but in all fairness they gave me a USB charger so I could carry on talking on Skype to friends.
