These fake bodies used in the medical field are called ‘phantoms.’ 

They’re used to train medical students in using x-ray machines, CT scanners, and other similar machines, or to test those machines. Many of them consist of real bones or organs encased in translucent material, though with the advent of 3D printing, artificially produced phantoms now exist as well.

These things are seriously unsettling and are all the more creepy when you see them lying on sterile tables or being fed into giant machines by smiling doctors. I would rather these body phantoms not exist anywhere near me, but I also guess I’m glad I’m not the one they’re testing radiation on.