My response usually gets their eyes rolling
Every time it is slightly mentioned about going through the machines, I just say 'One brain tumor in my life is enough for me'. They reply 'it cant hurt you'. I remind them 'that practicing medicine without a license will get them in a lot of trouble and their job is security not doctoring. They MUST not give me medical advise or comment about the claims of safety to someone that has a brain to have had a tumor in.'
The last few times, no argument or lecture from anyone that it was my fault I got felt up and inconvenienced (yes term I was given once) them.