Not sure if this belongs here or in the nuclear engineering forum. Many cancer patients in radiation therapy for cancer receive as much as 170-190 rads of daily radiation for 7-9 weeks. When I looked at a radiation chart I found that equates roughly to the dose at 1 mile from a Hiroshima type explosion on a daily basis. The former is, hopefully, curartive. The latter is, presumably, lethal. What's the difference? Is it the duration? Milliseconds for a nuclear blast vs minutes for radiation therapy? Or is it area covered? Whole body for nuclear blast vs focused for radiation therapy?