From the various threads on this and the LFP forum it seems that the US airports have a very relaxed attitude to scanning and security compared to Europe and other parts of the world.
The vast majority of airports outside the US won't hand scan film, they' also make you take bulky items out of pockets, jackets or coats have to be scanned, so it's difficult to bypass the scanners by putting film in your pockets. If they can't tell what an item is when they scan it the first time they'll make you take it out of your hand baggage & then they'll scan it again.
Contrary to what some people seem to assume the airport security hand-baggage scans are designed to be safe, both to the operators, messengers and film. In the UK, and I'd guess other countries, there's a committee made up of representatives from the major film companies, Ilford, Fuji & Kodak along with airport security authorities to ensure that the checks are safe for film.
The lead bags were originally made for older technology baggage scanners, the last time I saw one of these was at Philadelphia airport, but the airport was undergoing reconstruction at the time.
So the lead bags are probably a waste of time, the chances are you'll be asked to remove the film and then have it checked again.