[Zigurd]

Hopefully not being a tool about it, but mmwave and backscatter are different imaging technologies. Backscatter imaging is an x-ray technology, which, while very very low energy, uses ionizing radiation. Mmwave is not ionizing radiation.

[toomuchtodo]

I lumped them together on purpose (xray was previously used and was eventually repurposed for prisons by TSA, now millimeter wave is exclusively used by TSA), but your point and context is important and taken.