This impressive chart assembled by the web-based science "comic" XKCD shows how doses scale up in sieverts, the units by which absorption of radiation into living tissue is measured.
They are also looking into how changing certain gut bacteria may prevent obesity by remodelling intestinal tissue and thereby decreasing the absorption of nutrients in the gut.
Computer software analyses the total absorption of the light and detects the pulsating component of the absorption that originates from cyclic arrival of arterial blood in the tissue.