Nearly real-time visualization of 3-D volumes is crucial for the use of optical coherence tomography (OCT) during microsurgery. With an ultrahigh speed spectral domain OCT coupled to a surgical microscope, on-line display of 7.2 rendered volumes at 87 megapixels per second is demonstrated. Calculating the A-scans from the spectra is done on a quad-core personal computer (PC), while dedicated software for the 3-D rendering is executed on a high performance video card. Imaging speed is practically only limited by the readout of the camera. First experiments show the feasibility of real-time 3-D OCT for guided interventions.
In recent years a lot of new far red absorbing sensitizers for photodynamic therapy (PDT) were synthesized, like derivatives of bacteriopheophorbide. The possibility of increasing the accumulation in tumor tissue by coupling these dyes to carrier molecules is investigated. The photophysical properties of these dyes can be dramatically changed as a result of covalent binding to carrier molecules, different solvents, or biological surroundings. In heterogeneous systems 1O2 is strongly quenched. Therefore, its luminescence is difficult to detect. Another difficulty is the fact that especially far red absorbing sensitizers show fluorescence at the wavelength of 1O2-luminescence at 1270 nm, which can be several magnitudes higher than the luminescence of 1O2. The efficiency of singlet oxygen (1O2) generation is of major interest because 1O2 seems to play an important role in PDT. Time resolved luminescence measurements of 1O2 generated by dyes in micelles and liposomes in D2O were already made in our group. In order to investigate more complex systems and to avoid unwanted photochemistry we changed the excitation wavelength from UV (337 nm) to VIS/NIR(ND:YAG/OPO). The excitation power was increased and the detection limit was decreased. First measurements in red cell ghosts are presented.
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