To the best of my knowledge you cannot irradiate fresh vegetables successfully.
I have lived overseas in several countries where you bought special disinfectant solution to wash all fruits and vegetables before serving them. ALL restaurants used it as well. But no store is gooing to take the legal risk of treating that food for the customer.
This can be bought here but I have not seen any lately.
The recent removal from the shelves was supposed to be for Romaine Lettuce from California and Arizona. I have been eating all kinds of lettuce during this time with no problem...but then again I have lived in such diverse places as Cambodia, Sierral Leone and Egypt so my guts are full of great bacteria that protects me.