I did some reading and some testing: I agree to the post above. The fog I got on my negatives has nothing to do with Xray scanning.(posted 8230 days ago)For the Agfa APX 400: It was a full batch I bought shortly before doing my trip. I still had some rolls which did not do the trip. I developed one without exposing it through my camera: I have the same slight greyish fog than on the rolls which did the journey. Right now I still don't know who is the culprit: Film itself, Rodinal developer, light leak while loading the film... As I processed several rolls before, during and after my trip in another developer than Rodinal, I don't think light leak is the cause of fogging.
For the Tri X, I still have two unexposed rolls (which did a one way trip). When I have some spare time, I will develop one and see what I get.
Sorry for the false alert.