10 March 2015 Experimental studies with selected light sources for NIRS of brain tissue: quantifying tissue chromophore concentration
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Abstract
Near-infrared spectroscopy (NIRS) based techniques are utilised in quantifying changes of chromophore concentrations in tissue. Particularly, non-invasive in vivo measurements of tissue oxygenation in the cerebral cortex are of interest. The measurement method is based on illuminating tissue and measuring the back-scattered light at wavelengths of interest. Tissue illumination can be realised using different techniques and various light sources. Commonly, lasers and laser diodes (LD) are utilised, but also high-power light emitting diodes (HPLED) are becoming more common. At the moment, a wide range of available narrow-band light sources exists, covering basically the entire spectrum of interest in brain tissue NIRS measurements. In this paper, in the centre of our interest are LDs and HPLEDs, because of their affordability, efficiency in terms of radiant flux versus size and easiness to adopt in in vivo medical applications. We compare characteristics of LDs and HPLEDs at specific wavelengths and their suitability for in vivo quantifying of different tissue chromophore concentration, particularly in cerebral blood flow (CBF). A special focus is on shape and width of the wavelength bands of interest, generated by the LDs and HPLEDs. Moreover, we experimentally study such effects as, spectroscopy cross talk, separability and signal-to-noise ratio (SNR) when quantifying tissue chromophore concentration. Chromophores of our interest are cytochrome, haemoglobin and water. Various LDs and HPLEDs, producing narrow-band wavelengths in the range from 500 nm to 1000 nm are tested.
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Teemu Myllylä, Teemu Myllylä, Vesa Korhonen, Vesa Korhonen, Vesa Kiviniemi, Vesa Kiviniemi, Valery Tuchin, Valery Tuchin, } "Experimental studies with selected light sources for NIRS of brain tissue: quantifying tissue chromophore concentration", Proc. SPIE 9305, Optical Techniques in Neurosurgery, Neurophotonics, and Optogenetics II, 93051S (10 March 2015); doi: 10.1117/12.2076954; https://doi.org/10.1117/12.2076954
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