Hey guys, I wasn't exactly sure where to put this one--but figured here might be best. I went to the dentist this morning and they took two bitewing x-rays, which are a low amount of radiation (~0.038mSv). The claim is that, since we routinely receive ~3-4mSv per year due to radiation incident from space or domestic radioactive traces, it's not something to be worried about. I agree, and think it's a good argument--but one thing was bothering me. The problem with ionizing radiation is that it disrupts DNA replication, and in an unlucky case, the radiation can happen to knock out the wrong gene during DNA replication, leading to cells becoming cancerous and proliferating unchecked. However, if I recall my bio100 correctly, it takes several genes of your DNA to get knocked out to actually lead to cancer. So I'm wondering a couple of things. 1) This is biology related: if only one gene gets knocked out, will that cell line eventually die out, so say, in 10 years, that gene is no longer missing in any cells in your body (or at least is in a negligible number of cells). 2) This is the physics question I'm actually concerned about: 0.038mSv in a fraction of a second seems like it could be more dangerous than receiving 3-4mSv over a year. Further, these dental x-rays are concentrated on a specific area, and seem like they could do more damage than you are likely to get from other sources throughout the year. Can anyone offer any wisdom on this? I've been very curious about it. Here is my very rough source on the numbers: http://www.huffingtonpost.com/thomas-p-connelly-dds/dental-xray-radiation_b_960573.html . Feel free to contribute better numbers if mine are way too off. Thanks so much !