I did a lap of half the globe that involved 14 xrayings (carry-on) of my film, including once to get into Tiananmen Square. No effect whatsoever.

Reportedly the checked luggage scanners are higher power and I deliberately left a blank roll of Ektar in my checked luggage for a couple of flights to test that. No effect there either, but it was only Guangzhou-Melbourne-Adelaide and the both Melbourne and Guangzhou have very modern facilities and therefore probably low-power imaging scanners.