Radiation Hormesis

My memory of the study that showed that very low levels of gamma radiation could be beneficial was flawed. It happened in Taiwan rather than Japan. When I finally did a search without "Japan" it popped right up. This link to Wikipedia can lead you to a lot of information on the subject of radiation hormesis.
High levels of radiation are obviously harmful, even fatal, and the correlation between amount of exposure and harm is high. However, it is not obvious that a given dose of radiation given in a very short time is equally harmful as exactly the same dose given over a lifetime. It may be analogous to losing all of the blood I have donated over the years all at once. On the other hand, it is quite conceivable that a single gamma "ray" of exactly right energy could hit and break exatly the right bond of exactly the right DNA molecule in exactly the right cell at exactly the right time to trigger a cancer that defeats all the repair mechanisms to start.