I’m a radiation worker, I’m required to wear a dosimeter whenever I go into parts of the building near the nuclear reactor. This dosimeter is measured 4 times a year for radiation exposure. A few years ago there was a big problem because someone’s dosimeter showed a very large dose. It was found they’d accidentally brought it home and onto a flight. So two flights (a around trip) was enough to cause a bunch of alarms at a facility that actually monitors radiation exposure.