What things can detect x rays?

AnswerWhile I cannot think of any animal that can directly sense x-rays, it is not impossible to indirectly detect effects of radiation. Check out this article from 1966: http://www.jstor.org/pss/3949719 The article does not conclude how the rats sense x-rays, but it is clear to the researchers that they do. Also, I have often sensed x-rays. It feels sort of like a mild static electric charge, which is probably what it is. Especially on a hairy arm or leg you can sense a short burst of what feels like a mild static charge. I have not felt such an effect during dental x-rays, perhaps due to a lower power setting or lack of fluffy arm hair on the face. So in a way, you can indirectly sense the x-rays. Depending on the dose, you could also detect a heating effect, although this would never happen with a properly functioning medical instrument.