Experts say radiation is all around us -- from the rays of the sun to the granite beneath our feet.
A large percentage of our exposure to radiation comes from nature. And then there are the optional doses.
"The vast majority of man made radiation is self-elected from things we choose to have done like X-Rays and Cat Scans," said Charlie Zender, a UC Irvine professor.
Professor Zender says the average person is exposed to four millisieverts of radiation each year. How much is that? It's the equivalent of about ten Mammograms, or two Cat Scans.