It was today 115 years ago that William Roentgen discovered how to use x-rays to image objects. And as Motherboard's Michael Byrne notes, x-ray technology hasn't fundamentally changed since then.
Damnedest thing though: in those intervening 115 years, we're still basically shooting X-rays through bodies onto film. The technology remains about the same. We've dialed in the doses to keep it safer, sure, but the principle is one of those things simple enough that it resists evolution. We have MRIs now and various other body imaging systems--but we still use X-rays because it works. And it works cheaply, quickly, and used sparingly enough, safely.
The point is that doctors will be shooting X-rays through us in a 100 years.
As you all might expect, I love this line of thinking. Some human problems are roughly eternal. X-rays solved one these: how do you see your bones through your skin, or more generally, how do you see through opaque objects? An answer emerged in fundamental science -- use light with a smaller wavelength -- and it has continued to be useful for more than a hundred years.
There are plenty of other less fancy problems that we've solved with human implements that do not change. Knives and forks in modern form come to mind. Or, how about vice grip pliers? Stewart Brand once sang their praises in the pages of The Whole Earth Catalog. His review is so beautiful that I like to put line breaks in it, so you can see its poetry.