We propose to develop a digital radiography sensor, based on a fully dense transparent optical ceramic consisting of Lu2O3 doped with an appropriate luminescent lanthanide ion. We have already fabricated, by hot pressing techniques, transparent samples doped with Eu or Tb, and demonstrated that their respective red and green emissions are strongly excited by X-ray irradiation. The oxide has a density of 9.5 g/cm3 and a smooth absorption (free of K edges) between 10 and 64 keV, better than any known material, such as CsI or Gd2O2S. It has ideal characteristics for a match to a dental X-ray tube. The thickness of the detector layer will be between 100 and 200 microns. The same material but of different geometrical configuration can be used for X-ray CAT scanners, also surpassing the performance of present day materials. Phase I will seek to improve ceramic fabrication (possibly exploring alternative sintering techniques) and to characterize performance (light output, decay, emission spectra). Beyond Phase I we see two different thrusts, one towards dental applications, the other towards CAT. Segmentation of the ceramic will be an important aspect. We believe that the proposed work will result in better X-ray scintillator materials than any now available. PROPOSED COMMERCIAL APPLICATION Because currently available X-ray phosphor screens cannot provide the necessary spatial resolution, medical radiography has been unable to tap the full potential of digital techniques for data acquisition and processing. The development of a material that can fill this need will revolutionize radiological techniques and greatly enhance their diagnostic power. The immediate market includes both dental and tomographic imaging, and potentially extends to virtually every X-ray machine now in use.