Post often goes through similar machines to carry-on luggage, if suspicious then it might be x-rayed.
Carry-on luggage scanning isn't Xray, all UK airports use scanners that are film safe for a high number of passes. When I visited South America some of my films were scanned around 20 times with no problems.
In some countries scanners are used on entering the country also at shopping centres, also scanners are used routinely on cruise ships every time you board.
Over the past 7/8 years many of my films have been scanned many times and I don't have any worries about it at all. Most European airports, ports etc won't do hand searches and in fact you're at more risk of having film exposed and ruined.