What do they do to you at the Canada/US border?

Question

At border back into the US from Canada on 5, everybody stops in front of these white flat plastic things facing the vehicle at different angles, 8 total, I think. They are positioned sort of like they are scanning the vehicle in some way & have conduit that goes to a control panel or box of some sort. Then the border agent has some sort of hand held scanner that he scans the left side of the vehicle with. When I got to the border agent he kept asking me if anybody in the car had had a recent stress test or body scan or was in the hospital. He kept asking & I said no. What did he find/sense/whatever that could indicate somebody had a body scan or stress test? I know sometimes for stress tests they inject you with a radioactive dye for the imaging; can the border agents detect radioactive activity? If so, should I be alarmed that something in my car or on one of us caused them to think we had recently been scanned? What are those things that look like scanners? What can they detect?

Answer 1

the scans include visual  (television cameras to run your license plates) and radiation scans to detect radioactive materials.  Certain medical tests involve radio-isotopes and yes they would show.

Answer 2

They sure can that is what these machine are for . Radioactivity is like electricity and it can detected . . if you wear a pace maker at the airpeort it will pick it up immediately and they ask you go to anther line . They can detect body heat as well radio activity as most bombs are radio active .