When traveling with a camera, the safest way to deal with airport security checks is not to have your film zapped at all. Instead of passing film through the machine, carry it in a clear plastic bag and ask for a hand inspection.
If your request for a hand search is denied (always a possibility when traveling abroad) there's not much you can do but send your film through and hope for the best.
The September issue of Popular Photography says: ". . . X-ray damage to film by airport surveillance equipment is vastly overrated and not much of a problem. Eastman Kodak has received thousands of examples of alleged X-ray damage and has found that less than 1 percent had actually been damaged by radiation -- and a fair percentage of that 1 percent was irradiated by sources other than airport security devices."