Originally Posted by sethb

Total dose is irrelevant. Getting into a 104 degree hot tub I have more "total dose" of heat entering my skin than pouring a cup on boiling water on myself. Yet the former is pleasantly relaxing and the latter can require hospitalization for third-degree burns. A chest x-ray delivers radiation fairly uniformly throughout a large volume of the body. The nudiscopes deliver it all to the skin, a much lesser volume. The effects of radiation are not linear.