spaceman, it cost me nothing, my boss said , yeah go ahead xray the helmet!! You could see the inside material, any holes or cracks will show up black, cracks like spider webs, or black lines, holes, will be black, like the vent holes , they show up black. But do the helmet companies look for more subtle impact impressions, that I don't know. I just know from xray experience, what a crack or hole would look like.
And Daffe is right about the ultrasound ( we have one of them at work also I use on a daily basis) The surface also may not take the ultrasound waves, they may just bounce right off and you'd see nothing.
Just got the films in the mail... pretty good contrast. settings looked perfect. tried scanning it in, but with the dark film, the scanned images don't do it justice - maybe that's why we still read them on a viewbox.
some of the hospitals have digital x-ray processors that digitized the image. Best thing to do is to probably take a PHOTO of it then upload it.