[thinkharder]

I had a similar experience. I show up at the ER and they do their thing. Doctor says, "the symptoms indicate appendicitis, but the tests (which are mostly just poking you in the side and seeing how bad it hurts) are inconclusive. Normal procedure is to send you home and see how it goes, but I'd really feel more comfortable if we took a CT scan to be sure". At this point I'm in so much pain if he said he wanted to do a voodoo ceremony, I'd have been all in. CT scan reveals I had a weirdly shaped appendix, hidden behind a couple of folds of intestine, in a slightly different area than they are usually in. So the poking test didn't work cause they were poking around in the wrong area. If they'd sent me home I'd have come back with a burst appendix, which is potentially fatal. Ironically, just as they were wheeling me into the operating room, a woman came into the ER with an actual burst appendix so they wheeled me out and took her first.

I had a dog who started having a runny bloody nose all the time. 4 xrays, 2 nasal endooscope procedures and several thousand dollars and still can't figure out what's wrong. In desperation took him to a really good emergency/surgery vet clinic, they did a CT scan and it reveals a large tumor growing on the nasal cavity side of the soft palate. Confirmed with an endoscope going into the mouth and back up into the sinuses, couldn't see it from the front. Super frustrating because it was too late to do anything at this point.

I think using CT scans in the context of a checkup, to look for problems, is bad, because as discussed elsewhere on this thread, if you go looking for something, you'll find something. But if you already know there is a problem, they're the best tool we have for looking inside the body without cutting.