[Ratfish]

Have you a source for that? I could well believe that the cancer risk is low and obviously is is uncommon for a dose of radiation to be large, but 'comparatively large' doses of radiation are given regularly in hospital catheter labs, CT/PET scanners. And while generally these would be in the 10-20-30 mSv range, for many patients scans are repeated regularly for long time periods, rapidly reaching the 150-500mSv range discussed in the below article. Of course this is a fractionated dose and it would be much more dangerous as a single hit. I cannot find any reference to radiation dose verses cancer risk. Somewhat supporting you is this article which discusses over estimation of dose risk. Interesting discussion too: http://www.nejm.org/doi/full/10.1056/NEJMc073513