Browsing by Author "Tuchin, Valery Victorovich"
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- Fast Estimation of the Spectral Optical Properties of Rabbit Pancreas and Pigment Content AnalysisPublication . Martins, Inês Soraia; Silva, Hugo Filipe; Tuchin, Valery Victorovich; Oliveira, Luís ManuelThe pancreas is a highly important organ, since it produces insulin and prevents the occurrence of diabetes. Although rare, pancreatic cancer is highly lethal, with a small life expectancy after being diagnosed. The pancreas is one of the organs less studied in the field of biophotonics. With the objective of acquiring information that can be used in the development of future applications to diagnose and treat pancreas diseases, the spectral optical properties of the rabbit pancreas were evaluated in a broad-spectral range, between 200 and 1000 nm. The method used to obtain such optical properties is simple, based almost on direct calculations from spectral measurements. The optical properties obtained show similar wavelength dependencies to the ones obtained for other tissues, but a further analysis on the spectral absorption coefficient showed that the pancreas tissues contain pigments, namely melanin, and lipofuscin. Using a simple calculation, it was possible to retrieve similar contents of these pigments from the absorption spectrum of the pancreas, which indicates that they accumulate in the same proportion as a result of the aging process. Such pigment accumulation was camouflaging the real contents of DNA, hemoglobin, and water, which were precisely evaluated after subtracting the pigment absorption.
- The Optical Clearing Method: A New Tool for Clinical Practice and Biomedical EngineeringPublication . Oliveira, Luís Manuel Couto; Tuchin, Valery VictorovichThis book describes the Optical Immersion Clearing method and its application to acquire information with importance for clinical practice and various fields of biomedical engineering. The method has proved to be a reliable means of increasing tissue transparency, allowing the investigator or surgeon to reach deeper tissue layers for improved imaging and laser surgery. This result is obtained by partial replacement of tissue water with an active optical clearing agent (OCA) that has a higher refractive index and is a better match for the refractive index of other tissue components. Natural tissue scattering is thereby reduced. An exponential increase in research using this method has occurred in recent years, and new applications have emerged, both in clinical practice and in some areas of biomedical engineering. Recent research has revealed that treating ex vivo tissues with solutions containing active OCAs in different concentrations produces experimental data to characterize drug delivery or to discriminate between normal and pathological tissues. The obtained drug diffusion properties are of interest for the pharmaceutical and organ preservation industry. Similar data can be estimated with particular interest for food preservation. The free water content evaluation is also of great interest since it facilitates the characterization of tissues to discriminate pathologies. An interesting new application that is presented in the book regards the creation of two optical windows in the ultraviolet spectral range through the application of the immersion method. These induced transparency windows open the possibility to diagnose and treat pathologies with ultraviolet light. This book presents photographs from the tissues we have studied and figures that represent the experimental setups used. Graphs and tables are also included to show the numerical results obtained in the sequential calculations performed.