While exposed (but undeveloped) film can go through airport security, it is highly sensitive to the radiation used in modern scanners. Older X-ray machines generally do not damage low-speed film (ISO 800 or below) in a single pass. However, many airports have upgraded to CT (Computed Tomography) scanners, which are significantly more powerful. These new machines can "fog" or create grain patterns on your film in just one scan, regardless of the ISO. Professionals and hobbyists strongly recommend requesting a "hand check" from security officers to bypass the machine entirely. To do this, you should remove the film from its plastic canisters and place it in a clear Ziploc bag. While most TSA agents in the US are trained to honor this request, some international airports may refuse. If you must go through a scanner, avoid putting film in checked luggage, as those machines are much stronger than the ones for carry-ons and will almost certainly ruin your shots.