Because of the nuclear disaster in Japan, people all over the world are in a panic to get some kind of iodine in their bodies. People in China are in a panic buying salt, the bad way to get iodine. Potassium Iodide is only for emergencies and needs to be taken carefully. The very best way to put iodine in a person's body is in some natural way, like eating sea vegetables, especially kelp.
So, the best way to protect yourself from radiation is to eat sea vegetables, which I have been doing for years. To test yourself to see if you are deficient in iodine, put some iodine on the underside of your arm. If your body needs iodine, it will suck it in your body in less than an hour. If it stays all day without disappearing, you are not deficient. This would apply in most cases, but not all. If in doubt, have a doctor check on that for you.