IntroductionThere is probably no technical invention which has changed more within the medical world than the discovery of the x-rays by Wilhelm Conrad Röntgen in 1895 who explicitly never filed a patent in order to facilitate the widespread availability of his invention. His discovery was indeed groundbreaking, and modern medicine is unthinkable without x-rays. Although most of the many developments in the field of imaging appear to be of modest importance compared to Röntgens invention, modern imaging seems unthinkable without the tremendous developments of the last decades. While the future of Radiology seems to be in molecular imaging based on novel tracers, the present is unimaginable without the past technical evolution which was characterized by brilliant engineers who have breathlessly shortened the time spans needed for closing technological gaps defined by an equally breathless medical community. As the footprints got bigger with the devices growing from simple gamma cameras ...