I may be able to help a bit here. I used to travel for a living, in and out of airports twice a week every week until last year. I took a lot of film with me.
First of all, the TSA has film guidelines on their website. They insist that film up to ISO 800 won't be harmed by x-rays going through carry-on inspection, but say NOT to check your film unless it's been DEVELOPED. Not exposed, developed. The baggage scan WILL ruin it if you check your film with your bags, it is very powerful.
I don't believe them about the x-ray damage - because the damage is cumulative, not based on ISO. Enough exposure and any film will suffer to a noticeable degree. That means even ISO 100 will have a problem if it goes through 5 or more scans.
Yes, you can REQUEST a hand-inspection. I have had mixed luck. I know, I know, some of you have had 'no problems'. Well, what can I say? Maybe it was the "TSA Sucks" T-shirts I used to wear in the airport. But sometimes they'd refuse to hand-inspect.
Other times, a 'hand inspection' meant they took the film out of the foil wrappers (120 film) and ran it through the x-ray five or six times. Seriously.
And sometimes it meant that they just asked - "Is this professional film" and I'd nod yes and they'd hand inspect it.
A lead bag is NOT RECOMMENDED. The x-ray machine sees an obscured object. Guess what they want to look at REALLY BADLY now? The thing they can't see into. Don't do it. You end up with the TSA anal probe. Believe me and don't ask me how I know that.
What often works is this - carry all your film in a labeled, clear, baggie. Put at least one or two rolls of ISO 1600 film in it along with your other film. In fact, I had a sacrificial roll of Ilford 3200 for just that purpose. I'd point out that I had 'fast' film and they would often accede to my request.
If you're only going to pass through security once or twice with less than ISO 800 film, I'd say forget about it and just go on through. I haven't seen any difference, but you never know - you pays your money and you takes your chances, etc.
And don't refer to the TSA guys as swill sucking weasels who would rob their grandmothers for crack money if you know what's good for you. They have a special room at the airport for people like that. Oh yes. And then the doctor comes in and he...oh god. I can't go on. Just don't do that. Peeing yourself is so undignified.
Good Lord, I'm snockered. Gotta to go bed.
Best Regards,
Bill Mattocks