I work with radioactive materials on a regular basis in my job. As a cardiologist, my primary use for radioactive materials is during nuclear stress tests. During my training, in addition to all the usual patient care stuff, I have to take a separate training course on radiation and the safe use of nuclear materials. Radiation has been in the press a lot over the past few years, especially medical radiation. There are horror stories about people getting hundreds of times their expected dose and concerns about what the rapid rise of CAT scans will mean. Of couse, some have already decided that this is very bad. They may be right, but the conclusion is based on the opinion of experts without strong evidence of harm. (side note: ultrasound tests do not use radiation, and any from MRI is negligible) Just last month, the FDA recalled generators which provide radioactive material for heart stress tests because of the generators possibly leaking substances other than the ones we expect to inject. People have also become concerned about the radiation from scanners at the airport. While I have concerns about the privacy implications of these scanners, the radiation should not be a big concern seeing as how the radiation from a single scan is only 1% of the radiation you get from actually being on the flight.
Anyway, my impetus for this post is new information on a website that I found useful for people concerned about this topic. It is on the website of the International Atomic Energy Agency (IAEA), who regularly publishes an email titled Radiation Protection of Patients (RPOP). The new page is a sort of FAQ about radiation. It focuses on medical radiation, but does a good job of putting it into the perspective of everyday radiation sources. It also tries to explain just how complex the issue really is. For example, the best data we have on radiation and its risks comes from atomic bomb survivors, but this kind of exposure is very different from one CAT scan and it tells is very little about what it would mean to have a CAT scan every year for a decade. Furthermore, the "dose" you get from a CAT scan is only focused on one area of your body, whereas the data we have depends on the assumption that you were exposed to your whole body. Anyway, the material is good, but is written at a level that might not be easy to understand.