Wow! I never even considered that. I remember seeing something about that in an art forgery documentary. I think it was about a pre-war Picasso painting. One of the ways they determined it was a forgery made after WWII was that the elemental testing of the pigments showed the radiation signature of being created after 1945. Here's a similar article:
https://www.livescience.com/43178-nu...-painting.html