On medical devices, where the PC is a terminal or controller for the rest, like RTG or CT machines, you don't get Windows shell and launch the app. You boot the computer, it will boot straight to the control app and the app actively prevents switching to something different. You can only use this controller app on the machine.

The folks at hospitals are not going to fight with such an expensive machine, not even for updates - if something goes wrong, they would be to blame, they can live without that.