But here's the thing: PET scans!
It's antimatter! So you could call a PET scan a "CT scan" where CT means contra-terrene if you wanted to confuse everyone.
first, the tracer goes exactly where you want it, and no other parts of the body clutter up your scan
secondly, gamma rays aren't blocked by anything short of thick lead or concrete, so they can be detected as if your body wasn't even there.
So if you've ever wondered why a hospital might have a particle accelerator, this is why.
I mainly share this cause of this fun image of one being tested on a very Disney-heavy PET scanner.
It's roughly 0.1 µSv
If you lived near Three Mile Island during the partial melt-down, you got about 800 bananas worth of radioactivity.
But bananas are far sillier.