[RK]

The volume of the body that's exposed to the radiation is smaller and that makes the energy absorbed per volume much higher.

Much higher than what?

I think the health risks are probably overplayed. I've only seen one article quoting an expert, David Brenner, and that seemed somewhat out of context. He points out that the primary risk is going to be skin cancer and problems for people with certain genetic syndromes that are hypersensitive to radiation, like ataxia-telangiectasia.

These machines don't come anywhere near producing the doses necessary to cause temporary or permanent sterility in males (0.5 Gy and 6.0 Gy) or females (2-12 Gy). 1 Gy = 1 J/kg. But more importantly, the radiation isn't energetic enough to penetrate to your gonads, that's why it's suited for backscatter imaging.

The privacy, etc, is a whole different issue...