Novel Nanorods for High Efficiency Medical Imaging Applications

DESCRIPTION (provided by applicant): A new class of high-performance X-ray phosphor screens will be developed based on dot-in-a-rod core/shell nanorod (NR) structures embedded in transparent polymer matrices, with applications to protein crystallography, digital radiography and mammography, as well as a host of other important imaging and lighting applications. The goal is to achieve high spatial resolution, very fast time response, minimum afterglow, minimum self-absorption and excellent X-ray conversion efficiency. Our nano- composite phosphor screens will be X-ray tested by Radiation Monitoring Devices (RMD) and compared with equivalent spherical quantum dot (QD) screens and conventional micro-crystalline ZnSe:Cu,Cl and Gd2O2S:Tb phosphor screens. Although phosphor screens made from micron-sized phosphors are efficient, bright X-ray converters, their large particle size produces a great deal of scatter, which limits their spatial resolution. Preliminary theoretical and experimental studies show that nanophosphors in a transparent polymer-matrix screen exhibit significantly higher spatial resolution than micron-sized phosphor particles. Compared with spherical QDs, NR exhibits much larger Stokes shift to minimize self-absorption. In addition, their fast decay times and low afterglow characteristics will ensure response times orders of magnitude faster than existing phosphors. Moreover, to increase X-ray absorption, NR structures can be made from high-Z materials to increase X-ray absorption and their spectral emission tuned to match the spectral sensitivity of CCD sensors. Specifically in Phase I, we will prepare NR structures and related screening techniques, and quantify their X-ray photoluminescence performance. Success in Phase I will be proven if we can show that these NR structures are significantly better than existing micron-sized crystalline phosphors and conventional spherical quantum dots, in terms of spatial resolution, time resolution, and self-absorption. In Phase II, we will develop the techniques to synthesize large quantities of high quality nanocrystals, and optimize large screen characteristics for protein crystallography and medical imaging CCD detectors. NR-based X-ray converting films will have significant applications in digital radiography, crystallography, mammography, and various other biomedical imaging applications, enhancing their value to the NIH and to the molecular biology and medical communities as a whole. PUBLIC HEALTH RELEVANCE: The proposed nanorod luminescent structures will significantly enhance the performance of X-ray imaging compared to current state-of-the art. They will have applications in digital radiography, crystallography, and various medical imaging applications, enhancing their value to the NIH and to the molecular biology and medical communities as a whole.