I am hypo-thyroid, Hashimoto's. I just had to have a chest CAT ? Scan in which they injected radioactive iodine into my blood. I was advised it can give you strange sensations and I felt it in my thyroid area as well as elsewhere. I'm a bit concerned now as I see that Radioactive iodine treatment is used to kill off over-active thyroid. Does anyone have any info on this? Is the dose for CAT scan minimal?