Doesn't make a lick of sense to me, though. The reason given in the comic was because she's of the "old gods". But there are a numbers problems with that.
1. Diana is a Demigod not a New God.
2. The News Gods come from a different dimension, not from Diana's world.
3. The New Gods, as far as I am aware, aren't related to the Greek pantheon. They aren't family and have no connection with each other.
Thus, Diana shouldn't even be effected by Radion.
So same element that can kill even a darkseid can be lethal to her now?