Upconverting Luminescence Imaging and Tomography for Biomedical Applications

摘要: Tissue optics is a field devoted to study the interaction of light with tissue. Over last decades, much thanks optical spectroscopy, knowledge tissue has been steadily increasing. This catalyzed interest in applying as clinical tool. thesis studies an area within dealing fluorescence molecular imaging and tomography. For most visible wavelengths, does not penetrate more than few millimeters into But diagnostic window (∼ 600 1600 nm), penetration up several centimeters possible. opens possibility fluorescent contrast agents deep Fluorescent notable importance biomedical applications. Shimomura, Chalfie Tsien were recently rewarded Nobel prize for discovering developing green protein, which become very important marker. can, example, be used biological responses from drugs small animals over period time, without need sacrifice them. Currently, considerable amounts research are being performed enable three-dimensional reconstructions agent distributions inside animals, so called The tomography have long adversely affected by ever-present endogenous autofluorescence. autofluorescence conceals signal when using Stokes-shifted fluorophores, effectively limiting signal-tobackground sensitivity. In this thesis, it shown that replacing traditional fluorophores upconverting nanocrystals, possible avoid nuisance nanoparticles emit shorter wavelength their excitation wavelength, shifting region where no present. Experiments on phantoms, realistic properties, performed, was detect autofluorescence-free signal. Also theoretical framework nanocrystals tomographic reconstruction derived. Simulations based framework, showing promising results. Based results presented we believe may well envisaged markers purposes. Table Physical Quantities Symbol quantity Definition Units φ(r, ŝ) Radiance W/msr Φ(r) Fluence rate = ∫ 4π dΩ W/m n Refractive index c Speed c0/n m/s μa Absorption coefficient 1/m μs Scattering μtr Transport attenuation + g asymmetry parameter – Reduced scattering μ ′ s (1− g)μs κ Diffusion 1/3(μs μa) m μeff Effective √ μa/κ η Upconversion efficiency I(ωf)/I(ωe) η2p two-photon 2 m/W