I can&#x27;t tell looking from the outside in what kind of scanner I&#x27;m about to go into, it&#x27;s not as if they are labeled on the outside.<p>Though on big and modern airports you will likely only see millimeter waves scanners.<p>Agreed that flying high in an airplane will give you an extra dose regardless, but that still does not mean that people do not get to make their own choices in things like these, if only for their mental comfort, no matter how misguided by the laws of physics that may be.<p>For an encore: people get to choose to be religious, even if there is no physics proof that a god exists and so on. People will base their decisions on all kinds of reasoning, some rational, others not so rational. Trying to reduce everything to a physics problem isn&#x27;t going to get you very far.