Optical properties of liver tumor tissues in the spectral range of 350-2000 nm in laser photothermolysis treatment
Successful plasmon photothermal therapy (PPT) of tumors sensitized by nanoparticles requires solving a number of problems related to the choice of a protocol for single or multiple administrations of nanoparticles, the dose and distribution of nanoparticles in tumor, as well as the irradiation dose. It is obvious that knowledge of the optical parameters of tumor tissue is a key point for both estimating the dose of radiation and assessing spatial distribution of laser radiation in tumor tissue in the course of photothermal therapy.
In this report the changes in the optical properties of rat tumors doped with gold nanorods after PPT were studied. For the study PEG-coated gold nanorods (GNRs) with size about 41 per 10 nm were synthesized. To obtain model tumors in rats, a suspension of cholangicarcinoma cells was injected subcutaneously. If the vascularization was enough three daily intravenous injections GNRs with concentration 400 μg/mL 72 hours before PPT were made. For irradiation, a diode laser LS-2-N-808-10000 (Laser Systems, Ltd., Russia) with a wavelength of 808 nm was used. The rats were withdrawn and sampling of tissues was performed just after PPT. The main tumor layers were: a capsule of a tumor, the peripheral part of the tumor containing the main blood vessels, and the necrotic nucleus. The samples corresponding to tumor layers was sandwiched between two glasses and spectra of total and collimated transmittance, as well as diffuse reflectance were registered in the wavelength range of 350-2000 nm. Control samples of the same tumor layers without irradiation were also measured. By solving the inverse problem, the inverse Monte Carlo method for tumor tissues was used to calculate the absorption, scattering, transport scattering coefficients, and also the scattering anisotropy factor.
Vadim D. Genin
Saratov State University
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