Hi,
Theses are some standard procedures you can follow to prevent damage:
Rule number one is to never check your film. Carry it on with you. The checked baggage scanners are much, much stronger than the carry-on scanners, and there is really no question about whether or not your film is at risk: it is, and will probably be ruined. If you must check your camera stuff, carry a Holga or something in your carry-on bag, so you can show those ignorant of medium format film that yes, it really is film made to go into a real camera.
Then, try to get a hand inspection whenever possible. But if for some reason you cannot, don't fret. Film of any speed (even IR film, which is very sensitive to mishandling) easily survives repeated checked baggage x-rays just fine, as long as the machines are not ancient.
Rule number three is to not use any sort of radiation-shielded container to store your film. It will just arouse attention, and may even get the strength of the scanner jacked up by screeners trying to penetrate the shield.
Finally, get your processing done on the road whenever possible. That way there is no possible way that exposed film (the most important and the most sensitive kind of film) can be put at risk from x-rays. This is extreme, and not really necessary, but if there is a good pro lab in a place where you will be staying for a few days, I would go ahead and do it.
So, basically: 1) don't check your film, 2) request hand inspection (but don't worry if you don't get it), 3) don't try to shield your film with lead or whatever else, and 4) process your film if you can, rather than having traveling with it after exposure.
I follow all of these except number 2. I just scan the film. I am more scared of hand inspections ruining my film than x-rays from carry-on machines.