There is little doubt that x-ray technology (x-rays, CT scans, fluoroscopy) in medicine has done much good and is an invaluable diagnostic tool. Although I seriously question its usefulness as a therapeutic tool (e.g. cancer radiation therapy), that will not be the focus of this article.
X-rays are high-energy nuclear emissions that have the ability to pass right through tissue and leave an image on a film, called a radiograph (the film itself is not an "x-ray"). Less emission gets through denser tissue like bone, and more goes through soft tissue to darken the film. This results in the contrast, the picture of our insides, seen on the films