if you read the link you provided, you'd find mentioning of increased leukemia and thyroid cancer in humans and animals as result of such "therapeutic" exposure. And it is understandable because the ionizing radiation like sledgehammer hits varios accidental pieces of the internal cellular machinery. It is normal to see some repair machinery being activated in response, it is also normal that some pieces are just broken so that results in the cancer and other mutations.
Btw, the "ionizing radiation" is a very wide range of frequencies and their effect on the living matter is different (and such aggregate measure as dose/Sv takes only overall absorbed energy into account which provides only very general classification of the potential effects)
The only mention of thyroid cancer in that article was a single study of cobalt-60 exposure (unknown levels).
The point is, everyone here is getting all worked up over uSv exposure, when after they get on the plane, they are exposed to several thousand fold levels of radiation.
you just don't get it, don't you? The exposure amount is just one variable. Just for example of how exposure amount alone is meaningless to determine the outcome - locally deposited ~60Sv (with ~20Sv deposited into healthy tissue) during radiotherapy course is rarely fatal while 5Sv received whole-body during the same period of time would almost always be fatal.
Maybe you don't get it? I'm guessing that's the case since you're using an extreme example.
The point is, the levels of radiation experienced in back-scatter scanners is several thousand fold LESS than that experienced while in flight. Both are total body exposures, although one could argue that the exposure times are different.
Either way the exposure is well below the limits that cause concern, therefore my original point (that low levels of radiation may be beneficial), still stands.
no. Again, you just don't get it. The absorbtion site and effects on it also depends on the type and frequency of the radition. Back-scatter is mostly absorbed by skin while the radiation experinced while in the flight comes in different frequency range (more energetic gamma rays which pass through and backscatter less from the matter, incl. aircraft shell and human body and thus result in more even absorbtion through the body).
Btw, the "ionizing radiation" is a very wide range of frequencies and their effect on the living matter is different (and such aggregate measure as dose/Sv takes only overall absorbed energy into account which provides only very general classification of the potential effects)