What was the first medical imaging device developed and what was its use?

Answer 1

In 1895 Wilhem Kkonard von Rontgen, German Physicist, 1845-1923 invented the x-ray machine.

Answer 2

I suspect Marie Curie and her husband found they could expose photographic plates with their radiation and hence form an image of skeletal structures. I don't know whether their work predated that of Roentgen and his discovery of X-Rays.