The Eye of the CT Scanner: The story of learning to see the invisible or from the fluorescent screen to the photon-counting detector.

Roentgen's photographs with the "new kind of rays" triggered a worldwide storm of enthusiasm in all social circles. It was a stroke of luck that the photographic dry plates available to him were also sensitive to invisible X-rays. The discovery, research and utilization of X-rays are based on methods for making them visible, from fluorescent screens to photographic plates and digital X-ray detectors. From this point of view, this paper aims to outline the 125-year success story of X-ray imaging from its discovery to the recent development of photon-counting detectors. The scientific-historical view during the transition from the 19 to the 20 century reveals an impressive period of profound scientific and social upheaval in which revolutionary discoveries and technological developments led to enormous progress in medicine. The cross-fertilization of physics and medicine and their combination with inventiveness, engineering and entrepreneurial spirit created the impressive possibilities of today's imaging diagnostics. This contribution accompanies the Roentgen Lecture the author gave on November 13, 2020 in Roentgen's birth house as part of its inauguration and the closing ceremony of the 101 Congress of the German Roentgen Society in Remscheid-Lennep. KEY POINTS:: · The development of computed tomography was a milestone in the methodological advancement of imaging with X-rays.. · In the detector pixel invisible X-rays are converted into digital electrical impulses, which the computer uses to create images.. · Photon-counting detectors could have significant diagnostic advantages for clinical applications.. CITATION FORMAT: · Schlemmer H, The Eye of the CT Scanner: The story of learning to see the invisible or from the fluorescent screen to the photon-counting detector. Fortschr Röntgenstr 2021; 193: 1034 - 1048.