IIRC the Concorde had radiation monitoring on the flight deck and crew routinely checked for probability of solar flares prior to departure.
Though, I also remember Brian Trubshaw writing that the only time that he saw the needle in the red (whatever that may have indicated) was when flying over certain known "sensitive" areas on the ground. I think that he mentioned Iran, at that time.
Would this problem not be more applicable to high-flying military aircraft? Or is their shielding more effective, of necessity?