It is common for most review papers on radiation therapy to begin by acknowledging a novel discovery that was awarded the first Nobel Prize in Physics: the X-ray by Röntgen in 1895. As vital as this discovery may be, perhaps since to the X-ray we owe many of the modern achievements in radiotherapy, we will focus on another startling fact. The birth of radiotherapy took place less than a year after Röntgen took the first ever Xray, belonging to his wife’s hand . It was in fact a Viennese physician, Leopold Freund, who first demonstrated the therapeutic use of X-rays as a form of treatment on a 5- year old girl inflicted with nevus pigmentosus pilosus. The following first half of the twentieth century witnessed an unprecedented growth and development surrounding this potentially curative technique not only in terms of invested resources but also interdisciplinary collaborations among physicists, engineers, technologists, and biologists.