scholarly journals Multi-layered tissue head phantoms for noninvasive optical diagnostics

2015 ◽  
Vol 08 (03) ◽  
pp. 1541005 ◽  
Author(s):  
M. S. Wróbel ◽  
A. P. Popov ◽  
A. V. Bykov ◽  
M. Kinnunen ◽  
M. Jędrzejewska-Szczerska ◽  
...  
Keyword(s):  
Optical Properties ◽  
Near Infrared ◽  
Optical Measurement ◽  
Human Head ◽  
Medical Diagnostics ◽  
Optical Parameters ◽  
Measurement Systems ◽  
Tissue Phantoms ◽  
Optical And Mechanical Properties

Extensive research in the area of optical sensing for medical diagnostics requires development of tissue phantoms with optical properties similar to those of living human tissues. Development and improvement of in vivo optical measurement systems requires the use of stable tissue phantoms with known characteristics, which are mainly used for calibration of such systems and testing their performance over time. Optical and mechanical properties of phantoms depend on their purpose. Nevertheless, they must accurately simulate specific tissues they are supposed to mimic. Many tissues and organs including head possess a multi-layered structure, with specific optical properties of each layer. However, such a structure is not always addressed in the present-day phantoms. In this paper, we focus on the development of a plain-parallel multi-layered phantom with optical properties (reduced scattering coefficient [Formula: see text] and absorption coefficient μa) corresponding to the human head layers, such as skin, skull, and gray and white matter of the brain tissue. The phantom is intended for use in noninvasive diffuse near-infrared spectroscopy (NIRS) of human brain. Optical parameters of the fabricated phantoms are reconstructed using spectrophotometry and inverse adding-doubling calculation method. The results show that polyvinyl chloride-plastisol (PVCP) and zinc oxide ( ZnO ) nanoparticles are suitable materials for fabrication of tissue mimicking phantoms with controlled scattering properties. Good matching was found between optical properties of phantoms and the corresponding values found in the literature.

scholarly journals In-vivo multilaboratory investigation of the optical properties of the human head

2015 ◽  
Vol 6 (7) ◽  
pp. 2609 ◽  
Author(s):  
Andrea Farina ◽  
Alessandro Torricelli ◽  
Ilaria Bargigia ◽  
Lorenzo Spinelli ◽  
Rinaldo Cubeddu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Human Head

Influence of Blood Glucose Level on the Scattering Coefficient of the Skin in Near-Infrared Spectroscopy

2011 ◽  
Author(s):  
Sachiko Kessoku ◽  
Katsuhiko Maruo ◽  
Shinpei Okawa ◽  
Kazuto Masamoto ◽  
Yukio Yamada
Keyword(s):  
Optical Properties ◽  
Infrared Spectroscopy ◽  
Blood Glucose ◽  
Blood Glucose Level ◽  
Glucose Level ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Monitoring Methods ◽  
Absorbance Spectra

Various non-invasive glucose monitoring methods using near-infrared spectroscopy have been investigated although no method has been successful so far. Our previous study has proposed a new promising method utilizing numerically generated absorbance spectra instead of the experimentally acquired absorbance spectra. The method suggests that the correct estimation of the optical properties is very important for numerically generating the absorbance spectra. The purpose of this study is to measure the change in the optical properties of the skin with the change in the blood glucose level in vivo. By measuring the reflectances of light incident on the skin surface at two distances from the incident point, the optical properties of the skin can be estimated. The estimation is a kind of the inverse problem based on the simulation of light propagation in the skin. Phantom experiments have verified the method and in vivo experiments are to be performed.

Synthesis and optical properties of emission-tunable PbS/CdS core–shell quantum dots for in vivo fluorescence imaging in the second near-infrared window

RSC Advances ◽  
2014 ◽  
Vol 4 (77) ◽  
pp. 41164-41171 ◽  
Author(s):  
Yoshikazu Tsukasaki ◽  
Masatoshi Morimatsu ◽  
Goro Nishimura ◽  
Takao Sakata ◽  
Hidehiro Yasuda ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Fluorescence Imaging ◽  
Near Infrared ◽  
Core Shell ◽  
Cds Quantum Dots ◽  
In Vivo Fluorescence ◽  
In Vivo Fluorescence Imaging ◽  
Infrared Window

This paper describes the synthesis and optical properties of PbS/CdS quantum dots for in vivo fluorescence imaging.

Safety Considerations for Sample Analysis Using a Near-Infrared (785 nm) Raman Laser Source

2003 ◽  
Vol 57 (5) ◽  
pp. 580-587 ◽  
Author(s):  
S. D. Harvey ◽  
T. J. Peters ◽  
B. W. Wright
Keyword(s):  
Near Infrared ◽  
Energetic Material ◽  
Experimental Studies ◽  
Thermal Response ◽  
Raman Laser ◽  
Medical Diagnostics ◽  
Laser Source ◽  
Analytical Technique ◽  
Nir Laser

Raman spectroscopy is often considered a nondestructive analytical technique; however, this is not always the case. The 300-mW 785-nm near-infrared (NIR) laser source used with many commercially available instruments has sufficient power to burn samples. This destructive potential is of special concern if the sample is irreplaceable (e.g., fine art, forensic evidence, or for in vivo medical diagnostics) or a hazardous energetic material (explosive or pyrophoric samples). This study quantifies the heat resulting from illuminating an extensive color array with a 785-nm NIR laser and relates these values to the hazards associated with Raman analysis. In general, darker colors were found to be more problematic. Since visible colors are not ideally correlated with absorptive characteristics at 785 nm, predictions based on thermography are not perfect; however, this approximation gives a useful method for predicting the thermal response of unknown samples to NIR exposure. Additionally, experimental studies evaluated the analysis of flammable organic solvents, propellants, military explosives, mixtures containing military explosives, shock-sensitive explosives, and gunpowders (i.e., smokeless, black, and Pyrodex powders). Safety guidelines for analysis are presented.

Optical Fiber Device and Biological Tissue Phantoms for Determination of Optical Parameters in the Near‐Infrared Region

2004 ◽  
Vol 32 (5) ◽  
pp. 489-505 ◽  
Author(s):  
Omar Feix do Nascimento ◽  
Antonio Balbin Villaverde ◽  
Renato Amaro Zângaro ◽  
Marcos Tadeu Tavares Pacheco ◽  
Steven F. Durrant
Keyword(s):  
Optical Fiber ◽  
Biological Tissue ◽  
Near Infrared ◽  
Infrared Region ◽  
Optical Parameters ◽  
Tissue Phantoms ◽  
Near Infrared Region

scholarly journals Optical investigation of bovine grey and white matters in visible and near-infrared ranges

2021 ◽  
Vol 27 (1) ◽  
pp. 99-107
Author(s):  
Ali Shahin ◽  
Wesam Bachir ◽  
Moustafa Sayem El-Daher
Keyword(s):  
Optical Properties ◽  
Absorption Coefficient ◽  
Wavelength Range ◽  
Grey Matter ◽  
Near Infrared ◽  
Biological Tissues ◽  
Integrating Sphere ◽  
Visible Range ◽  
Optical Investigation

Abstract Introduction: Due to enormous interests for laser in medicine and biology, optical properties characterization of different tissue have be affecting in development processes. In addition, the optical properties of biological tissues could be influenced by storage methods. Thus, optical properties of bovine white and grey tissues preserved by formalin have been characterized over a wide wavelength spectrum varied between 440 nm and 1000 nm. Materials and Methods: To that end, a single integrating sphere system was assembled for spectroscopic characterization and an inverse adding-doubling algorithm was used to retrieve optical coefficients, i.e. reduced scattering and absorption coefficients. Results: White matter has shown a strong scattering property in comparison to grey matter. On the other hand, the grey matter has absorbed light extensively. In comparison, the reduced scattering profile for both tissue types turned out to be consistent with prior works that characterized optical coefficients in vivo. On the contrary, absorption coefficient behavior has a different feature. Conclusion: Formalin could change the tissue’s optical properties because of the alteration of tissue’s structure and components. The absence of hemoglobin that seeps out due to the use of a formalin could reduce the absorption coefficient over the visible range. Both the water replacement by formalin could reduce the refractive index of a stored tissue and the absence of hemoglobin that scatters light over the presented wavelength range should diminish the reduced scattering coefficients over that wavelength range.

scholarly journals Examining cerebral hemodynamics in a two-layer model of the human head using broadband near-infrared spectroscopy

2021 ◽  
Author(s):  
Olivia Pucci
Keyword(s):  
Optical Properties ◽  
Near Infrared ◽  
Continuous Wave ◽  
Lower Layer ◽  
Homogeneous Medium ◽  
Human Head ◽  
Cerebral Hemodynamics ◽  
Layer Model ◽  
Adult Human ◽  
Two Layer Model

The development of a continuous-wave method is presented, to quantify accurately the optical properties of a two-layer model of the human head using a broadband spectral approach. In particular, focus is put on the reconstruction of the absolute absorption and scattering properties of a two-layered phantom model of the human head with steady-state multi-distance measurements by performing differential fit analysis of the near-infrared (NIR) reflectance spectrum between 700 nm and 1000 nm. The two-layer model approximation was fitted to experimental broadband absorbance measurements obtained from two-layered phantoms with known optical properties. Results demonstrated that the suggested method was able to determine the optical properties of the lower layer with minimal error at specific source-detector distances. Preliminary results on the non-invasive measurement of the optical properties of the adult human brain in a two-layer approximation are presented. Finally, a mobile wireless NIR device is used to measure changes in the temporal characteristics of cerebral hemodynamic responses to functional brain activity, in particulaur the effect of smoking. Results suggest that assuming homogeneous medium for the adult human head severely underestimates the changes in cerebral hemodynamics. Hence, it is important to take surrounding layers into consideration when performing cerebral measurements using NIR spectroscopy.

scholarly journals Validation of an Inverse Fitting Method of Diffuse Reflectance Spectroscopy to Quantify Multi-Layered Skin Optical Properties

Photonics ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 61 ◽  
Author(s):  
Chiao-Yi Wang ◽  
Tzu-Chia Kao ◽  
Yin-Fu Chen ◽  
Wen-Wei Su ◽  
Hsin-Jou Shen ◽  
...  
Keyword(s):  
Optical Properties ◽  
Diffuse Reflectance ◽  
Volume Fraction ◽  
Diffuse Reflectance Spectroscopy ◽  
Reflectance Spectra ◽  
In Vivo Studies ◽  
Process Time ◽  
Optical Parameters ◽  
Fitting Procedure

Skin consists of epidermis and dermis layers that have distinct optical properties. The quantification of skin optical properties is commonly achieved by modeling photon propagation in tissue using Monte Carlo (MC) simulations and iteratively fitting experimentally measured diffuse reflectance spectra. In order to speed up the inverse fitting process, time-consuming MC simulations have been replaced by artificial neural networks to quickly calculate reflectance spectra given tissue geometric and optical parameters. In this study the skin was modeled to consist of three layers and different scattering properties of the layers were considered. A new inverse fitting procedure was proposed to improve the extraction of chromophore-related information in the skin, including the hemoglobin concentration, oxygen saturation and melanin absorption. The performance of the new inverse fitting procedure was evaluated on 40 sets of simulated spectra. The results showed that the fitting procedure without knowing the epidermis thickness extracted chromophore information with accuracy similar to or better than fitting with known epidermis thickness, which is advantageous for practical applications due to simpler and more cost-effective instruments. In addition, the melanin volume fraction multiplied by the thickness of the melanin-containing epidermis layer was estimated more accurately than the melanin volume fraction itself. This product has the potential to provide a quantitative indicator of melanin absorption in the skin. In-vivo cuff occlusion experiments were conducted and skin optical properties extracted from the experiments were comparable to the results of previously reported in vivo studies. The results of the current study demonstrated the applicability of the proposed method to quantify the optical properties related to major chromophores in the skin, as well as scattering coefficients of the dermis. Therefore, it has the potential to be a useful tool for quantifying skin optical properties in vivo.

scholarly journals Development of a handheld diffuse optical breast cancer assessment probe

2016 ◽  
Vol 09 (02) ◽  
pp. 1650007 ◽  
Author(s):  
Majid Shokoufi ◽  
Farid Golnaraghi
Keyword(s):  
Breast Cancer ◽  
Optical Properties ◽  
Breast Tissue ◽  
Near Infrared ◽  
Human Subjects ◽  
Breast Cancer Diagnosis ◽  
Functional Brain Imaging ◽  
Wide Range ◽  
Concentration Changes

Diffuse Optical Spectroscopy (DOS) is a promising non-invasive and non-ionizing technique for breast anomaly detection. In this study, we have developed a new handheld DOS probe to measure optical properties of breast tissue. In the proposed probe, the breast tissue is illuminated with four near infrared (NIR) wavelengths light emitting diodes (LED), which are encapsulated in a package (eLEDs), and two PIN photodiodes measure the intensity of the scattered photons at two different locations. The proposed technique of using eLEDs is introduced, in order to have a multi-wavelength pointed-beam illumination source instead of using the laser-coupled fiber-optic technique, which increases the complexity, size, and cost of the probe. Despite the fact that the proposed technique miniaturizes the probe and reduces the complexity of the DOS, the study proves that it is accurate and reliable in measuring optical properties of the tissue. The measurements are performed at the rate of 10[Formula: see text]Hz which is suitable for dynamic measurement of biological activity, in-vivo. The multi-spectral evaluation algorithm is used to reconstruct four main absorber concentrations in the breast including oxy-hemoglobin (cHb), deoxy-hemoglobin (cHbO2), water (cH2O), fat (cFat), and average scattering coefficient of the medium, as well as concentration changes in Hb ([Formula: see text]cHb) and HbO2 ([Formula: see text]cHbO2). Although the probe is designed for breast cancer diagnosis, it can be used in a wide range of applications for both static and dynamic measurements such as functional brain imaging. A series of phantoms, comprised of Delrin[Formula: see text], Intralipid[Formula: see text], PierceTM and Black ink, are used to verify performance of the device. The probe will be tested on human subjects, in-vivo, in the next phase.

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