The poor dude running the fluoroscopy might have to stay there the whole time. Source: I’m that dude. My personal record is about 9 hours, although I took a couple quick pee breaks. (Busy day so no longer term relief available.)

I’ve also seen a few cases where a partner comes in to relive the attending on particularly long spine cases. I’ve seen a couple 10-12 hour cases. I don’t have personal experience with those legendary 16-24+ hour traumas though.