CC BY
16B-I-17
Optical properties of human normal and pathological colorectal tissues from 200 to 1000 nm
I. Carneiro1, S. Carvalho1, R Henrique1, L. Oliveira2, V. Tuchin3 Portuguese Oncology Institute of Porto,
Department of Pathology and Cancer Biology and Epigenetics Group-Research Centre, Porto, Portugal
2Polytechnic of Porto - School of Engineering, Physics Department, Porto, Portugal 3Saratov state University, Research-Educational Institute of Optics and Biophotonics, Saratov, Russian Federation
Laser diagnostics and treatment procedures are commonly performed for visible and NIR wavelengths. The UV range is also of interest for clinical procedures, since some tissue chromophores present their absorption bands [1] and emit fluorescence in the UV range [2]. Skin diseases like psoriasis and vitiligo are commonly treated with UV light [3]. The UV range is also of interest due to the optimized refractive index matching that occurs in tissues in this range during optical clearing. Recent studies performed at optical clearing provided the discovery of two new tissue windows in the UV range that might allow the development of new diagnostic or treatment procedures [4], which will need the development of new light sources to work on the UV range. With the objective of evaluating the optical properties of tissues in a wide spectral range, and also to compare between normal and pathological tissues, we have obtained the wavelength dependencies for the optical properties of human normal and pathological colorectal mucosa between 200 and 1000 nm. The obtained results show great similarity to the ones we have previously obtained for the visible-NIR range, but provide greater information, showing the absorption peaks for proteins and DNA in the UV range. Comparing between the data obtained for normal and pathological mucosa, we observe that diseased tissue shows higher protein concentration. The obtained data was almost entirely calculated directly from experimental measurements, with the exception of the reduced scattering coefficient, which was obtained from inverse adding-doubling simulations.
References
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[2] I. J. Bigio and J. R. Mourant, Ultraviolet and visible spectroscopies for tissue diagnostics: fluorescence spectroscopy and elastic-scattering spectroscopy, Phys. Med. Biol., vol. 42, pp. 803-814, (1997).
[3] E. M. Cela, M. L. Paz, J. Leoni and D. H. G. Maglio, Immunoregulatory Aspects of Immunotherapy (IntechOpen), Chapter 5, (2018).
[4] I. Carneiro, S. Carvalho, R. Henrique, L. Oliveira and V. V. Tuchin, Moving tissue spectral window to the deep-UV via optical clearing, J. Biophotonics, submitted.
