If you are really worried about it most specialty camera shops sell x-ray proof bags that you can store your film in. Or you can always put it in your carry-on and ask the guard to inspect it personally instead of sending it through the machine. However, I have flown many times and never come back with ruined film.
As long as you are flying within the US, don't worry about your film. If you use an "x-ray proof" bag ( and I had one ), they just turn up the "volume" until they can see in it. No way will they let an uninspected bag on the plane. If you are still concerned, use a ziploc bag to carry your film in your carry on bag. Then ask to have it hand inspected when at the machine. They don't mind doing this and usually just hand to bag right back to you on the other side. The bag works well because you can put your exposed rolls right back into it. I used to toss them into the suitcase then play hide and seek among the undies once I got home. I have been traveling in the US and abroad since 1974 and have yet to get a ruined roll of film or video. Now a LOST roll is another story!
I believe that as long as you are not shooting very high speed film (1000 or greater), the x-ray machines won't harm it in the least. Have it all hand checked if you are concerned.
Have a wonderful time (and make sure you have plenty of film).
Jennifer
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