Above left: the first x-ray of the human body, taken by Conrad Röntgen on November 8, 1895. He called the new form of radiation he had discovered x-rays, with the X standing for unknown. It is an image of his wife's hand, which shows her ring. Above right: a modern x-ray image of a hand taken at the S. Mark Taper Foundation Imaging Center. One hundred and sixteen years has led to sharper, clearer x-rays.