I just went through this last week on a 10 day visit to Amsterdam. At each screening, I insisted the film be hand checked and not put through the x-ray. I have had too many photos ruined when checkers assured me the x-rays would not harm my film, so I don't take chances any longer.

I never - but never - have film loaded in the camera when going through screening. And I always take the film out of the plastic canisters and place the rolls in a baggie which I can then simply hand to the screener. Occassionally I will run into a stubborn screener who tries to give me a hard time about hand screening the film, but so far (knock on wood) I have been able to avoid x-raying.