I would believe that x-rays, because it being "light with a different wave lenght", behaves much like light.
Meaning, the stuff it doesn't penetrate 100%, can cause reflections, which causes the rays to spread and hit other objects "several times", instead of just one straight burst of x-ray.
Also, reflected x-rays may meet other reflected x-rays and create hotspots (much like waves meeting other waves in the sea, which can create "double-waves" with much more energy at that given point).
You are safe, the carry on scan is too weak to fog even 1600 iso Neopan.
- There have been incidents where small children have been playing on the airport and suddenly found themselves being scanned by the checked-baggage scanner. The reports in the media has always been that the scan isn't harmful to the child, so I doubt we are looking at a high-energy cobalt 60 source which will fry Superman. still, the checked baggage scan is no place for film.