How do you treat mouth lesions resulting from radiation

My mother had radiation to get rid of a keloid on her chest after multiple heart surgeries. My understanding is too much radiation was used and she developed several holes down the mid line of her chest. The doctor she was referred to attempted to graft the holes and sew them up, but I believe the radiation burned through it all now. She has a gaping wound the size of fist in the middle of her chest. I have lost confidence in the doctors responsible and I don't know where to go from here.