Notrightnow: yy to the idea of an image being in your head.
My work sometimes involves viewing disturbing images on film or stills, and although I obviously never bring that kind of material home, the dc know broadly what I do, so it does come up in conversation.
I have very clear limits about the kinds of material i will not work with for the sake of my own mental health, and I use that analogy with the dc when discussing film and game content, and have used the same argument to warn them about being tempted to watch pornographic stuff online. We all know this stuff is out there, if you go looking for it out of curiousity, you may get much more than you bargained for. Just because it exists doesn't mean that one should watch it - it's not some kind of macho contest to see who can be the hardest. There are good reasons we find certain images disturbing, and those reactions are telling you something useful.
I do worry a bit that teenage boys in particular do view it at least in past as a test of masculinity or adulthood, so I work very hard to counteract that.
Sorry, posted again to take out the weird crossing out!