Good question. I always put my film in a plastic ziplock that I will see when I’m taking my computer out of my carry on. Then I hand the security guard the film to “hand check.” Xray machines shouldn’t hurt film under 600 ISO, but it will fuck up, to some extent, polaroids, Instax and other instant film. So I always ask them to hand check all my film; just incase. Its time consuming, and international travel and hand checks can get very time consuming, but its the only sure fire way to have your film be unfucked by X-ray.