Three ways to limit our exposure to radiation would be "time", "distance" and "shielding".
Time references how much time you're being exposed to the radiation. Example, in the sun. Limit the time you're outside. In an x-ray exam room, they try and get you out very quickly.
Distance references how close you are to the radiation. Again, in an x-ray room, they try and keep the radiation as far away from you.
Shielding would be to block yourself with lead (x-ray) or sunscreen (for sun exposure) to help protect you for further exposure.
