Medical imaging has its roots in the accidental discovery of a new class of electromagnetic radiation, X rays, by Wilhelm Conrad Roentgen in 1895. The first X-ray radiograph ever taken was of his wife’s hand, revealing a picture of the living skeleton [1]. In the subsequent decades, physicians refined the art of X-ray radiography to image the structural and physiological state of internal organs such as the stomach, intestines, lungs, heart, and brain.