Interesting fact:

The X-rays were named as such, because the inventor was not sure what they are and chose the common X for an unknown quantity. Today x-rays are powerful medical diagnostic tool which can detect anything from broken bones to tissue changes when used in CAT scans. However, it’s all about the dosage. In the early days the potential negative side-effects were unknown and an X-ray craze developed. Besides an immediate medical application, x-ray machines popped up at carnivals and in shoe stores. People working with them got x-ray burns and Thomas Edison’s assistant died from skin cancer.