A male technician taking an x-ray of a female patient. This image was used to demonstrate the myth about exposure to radiation during the x-ray procedure. X-rays were discovered by the German physicist Wilhelm Roentgen in 1895. They were soon applied to medicine because of their ability to pass through soft tissues but not so easily through bone, which casts a shadow on photographic plate. It was some years before it was discovered that x-rays can cause cancer, particularly leukemia. No photographer credited, dated 1940.