Though I cant tell you there is no risk or exposure to radiation which is a very harmful substance I can tell you it is minimal if you are safe and follow rules and safety guidelines. You are well trained and you use protection such as lead vests and you are generally seperated by a wall or glass, there will be times where you just can't help but being exposed to small levels of radiation.
For some procedures and some patients you will need to stay in the room to help them hold still for imaging. This won't be for every patient or every procedure but from time to time it will happen.
As a tech you will wear a small device or badge called a Geiger counter or Geiger meter which will measure your exposure to radiation so it's not a mystery to you and you're not wondering how much you were exposed to. If your levels reach too high you will be sent home and won't return until your levels return to normal.
In your schooling and training they will teach you and educate you about problems that can arise from exposure to radiation. Health effects can run the gammit from radiation poisoning to cancer.
Your chances of this happening however are small due to all the precautions and safety measures you take.