X rays were first discovered by Wilhelm Rontgen, a German physicists, in 1895, when he hid a vacuum tube under a paper bag and a photosensible panel lit when a current was flowing through that vacuum tube.
He then discovered that these rays, which he named X rays due to their unknown nature, were simply going through soft tissues, but not through harder ones, like bones.
And here comes radiology, the means of taking photographs of our bones and the things we have in our bags. Rontgen got a Nobel prize in 1901, but he didn’t wanted to make any patents that were using the X rays. Such a nice guy!