Probing depth in diffuse reflectance spectroscopy of biotissues: a Monte Carlo study

Kurakina, Daria; Perekatova, Valeriya; Сергеева, Е. А.; Kostyuk, Alexey; Turchin, Ilya V.; Kirillin, Mikhail

doi:10.1088/1612-202x/ac4be8

Cited by 15 publications

(8 citation statements)

References 39 publications

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“…Ultraviolet-visible diffuse reflectance spectra (UV-vis DRS) of the sample powders were collected on a UV-vis spectrophotometer (JASCO-750, Japan). The non-absorbing BaSO 4 was used as the reference material [53]. The sample powders were also analyzed by X-ray photoelectron spectroscopy (XPS, AXIS Ultra DLD, Japan) with a monochromatic Al Kα X-ray source for the examination of their surface state.…”

Section: Materials Preparationmentioning

confidence: 99%

Boosting visible-light-driven water splitting over LaTaON2via Al doping

Yang

Chang

et al. 2022

Sci. China Mater.

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LaTaON 2 is an attractive visible-light-active photocatalyst for water splitting due to its broad visible light absorption as far as 650 nm and proper band edge positions. Notwithstanding these promising properties, LaTaON 2 generally exhibits poor photocatalytic activity because of its high defect concentration that severely hinders charge separation. Here, LaTaON 2 has been modified by doping Al into the Ta sublattice, i.e., LaTa 1−x Al x O 1+y N 2−y (0 ≤ x ≤ 0.20). Al doping not only inhibits the defect concentration and increases surface hydrophilicity but also maintains the desired visible light absorption of LaTaON 2 . These important modifications substantially ameliorate the charge separation conditions within LaTaON 2 and are responsible for a much enhanced photocatalytic performance for water redox reactions under visible light illumination. Under optimal conditions, the Al-doped LaTaON 2 delivers an apparent quantum efficiency of 1.17% at 420 ± 20 nm for water oxidation into O 2 , outperforming most LaTaON 2 -based photocatalysts. These findings highlight Al as a useful dopant to open up the photocatalytic potential of metal oxynitrides whose activity is often undermined by a high defect concentration.

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Section: Materials Preparationmentioning

confidence: 99%

Boosting visible-light-driven water splitting over LaTaON2via Al doping

Yang

Chang

et al. 2022

Sci. China Mater.

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“…In general, there are two approaches that precede quantitative optical measurement of the living body: numerical calculations using Monte Carlo methods [5][6][7] and experimental approaches using phantoms [8][9][10][11] that have wavelength-dependent scattering and absorption characteristics unique to living tissue. Many studies on the detection ef ciency of SDS by Monte Carlo methods have been reported [12,13]. However, there are few reports on diffuse re ected light intensity detected in variable incident angles and SDS.…”

Section: Introductionmentioning

confidence: 99%

Goniometric Examination of Diffuse Reflectance of a Skin Phantom in the Wavelength Range from 400 to 1600 nm

Kikuchi

Nagahori

Suzuki

et al. 2023

ABE

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Since all of noninvasive optical monitors such as near-infrared spectroscopy are transcutaneous, it is important to consider the optical properties of the skin. The purpose of the present study was to clarify the effects of incident angle and source-detector separation (SDS) on the detection of components in the dermal layer. Here, we developed a novel skin phantom consisting of epidermal and dermal layers with optical properties ranging from 400 to 1600 nm. The phantom was simulated by only water, scatters and absorbers, without agarose, silicone or other materials. The phantom showed re ectance spectra very similar to those of actual human skin by the integrating sphere measurements. Furthermore, an optical system was assembled in which the incident angle could be changed from 20º to 80º and the SDS from 0 to 6 mm independently. For the wavelength range of 400 to 900 nm, the absorption spectrum of hemoglobin in the dermal layer was investigated to assess detectability. For the wavelength range of 900 to 1600 nm, the absorption spectrum was con rmed by including glucose in the dermal layer. The absorbance was calculated from the measured diffuse re ected light intensity. The optimal incident angle and SDS for optical measurements focused on the dermal layer were estimated by the signal-to-noise ratio (SNR). In the wavelength range of 400 to 900 nm, the absorption spectrum of hemoglobin with the highest SNR was obtained at an incident angle of 70 and SDS of 4 mm. In the wavelength range of 900 to 1600 nm, the absorption spectrum of glucose with the highest SNR was obtained at an incident angle of 20 and SDS of 0 mm. These conditions are expected to be optimal for transcutaneous measurement of biomolecules within the dermis using diffuse re ected light of wavelength range from 400 to 1600 nm.

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“…Optical imaging techniques [5,6] benefit from both non-invasiveness and high sensitivity to blood oxygenation owing to significant difference in absorption spectra of oxy-and deoxyhemoglobin in optical spectral range. Traditionally, blood oxygenation level is estimated with diffuse optical spectroscopy (DOS) [2,7,8] based on the registration of the spectra of the probing radiation passed through the biological tissue and the subsequent reconstruction of the medium absorption spectra from the measurement data [9,10]. This approach, however, provides with the estimation of blood oxygenation value averaged over a particular measurement volume within biological tissue.…”

Section: Introductionmentioning

confidence: 99%

Combined Monte Carlo and k-Wave Simulations for Reconstruction of Blood Oxygen Saturation in Optoacoustics: A Pilot Study

Perekatova

Kurakina

Khilov

et al. 2022

J-BPE

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Optoacoustic (OA) imaging of biological tissues is a modern technique allowing for three-dimensional blood oxygen saturation mapping based on OA spectroscopy data. Since biological tissues are optically inhomogeneous and the spatial distribution of optical parameters within a biological tissue is a priori unknown, Monte Carlo simulation technique is traditionally used to estimate the distribution of probing illumination within tissues in quantitative OA reconstruction. Currently, machine learning techniques are actively employed for reconstructing 3D distribution of blood oxygen saturation or estimating optical properties of biological tissues based on training datasets. In this paper, systemic calculations of synthetic OA images of a medium with embedded vessel-like structures were performed to create a training dataset for machine learning employing combined application of the Monte Carlo technique for direct solution of optical problem and difference-space pseudo-spectral approach implemented through k-Wave Toolbox calculations for the acoustical part. The calculations were performed for probing wavelengths of 532 nm, 658 nm and 1064 nm, which are commonly employed in spectral OA imaging. Simulated OA data for different orientation, diameter and embedding depth of blood vessels allows analyzing the effect of these parameters on the formation of OA image and the reconstruction of blood oxygen saturation. The ratio of OA signals corresponding to probing wavelengths of 658 nm and 1064 nm was employed for simple reconstruction of blood oxygen saturation in silico for different vessel geometries with the precision of < 3-15% for the most of blood vessels diameters and embedding depths and the range of blood oxygen saturation values ≥ 0.8. The obtained set of synthetic OA data has high potential as a training set for employment in machine learning techniques aiming at mapping blood oxygenation based on spectral OA data.

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Probing depth in diffuse reflectance spectroscopy of biotissues: a Monte Carlo study

Cited by 15 publications

References 39 publications

Boosting visible-light-driven water splitting over LaTaON2via Al doping

Boosting visible-light-driven water splitting over LaTaON2via Al doping

Goniometric Examination of Diffuse Reflectance of a Skin Phantom in the Wavelength Range from 400 to 1600 nm

Combined Monte Carlo and k-Wave Simulations for Reconstruction of Blood Oxygen Saturation in Optoacoustics: A Pilot Study

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