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Rodriguez AJ, Vasudevan S, Farahmand M, Weininger S, Vogt WC, Scully CG, Ramella-Roman J, Pfefer TJ. Tissue mimicking materials and finger phantom design for pulse oximetry. BIOMEDICAL OPTICS EXPRESS 2024; 15:2308-2327. [PMID: 38633081 PMCID: PMC11019708 DOI: 10.1364/boe.518967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 03/03/2024] [Accepted: 03/03/2024] [Indexed: 04/19/2024]
Abstract
Pulse oximetry represents a ubiquitous clinical application of optics in modern medicine. Recent studies have raised concerns regarding the potential impact of confounders, such as variable skin pigmentation and perfusion, on blood oxygen saturation measurement accuracy in pulse oximeters. Tissue-mimicking phantom testing offers a low-cost, well-controlled solution for characterizing device performance and studying potential error sources, which may thus reduce the need for costly in vivo trials. The purpose of this study was to develop realistic phantom-based test methods for pulse oximetry. Material optical and mechanical properties were reviewed, selected, and tuned for optimal biological relevance, e.g., oxygenated tissue absorption and scattering, strength, elasticity, hardness, and other parameters representing the human finger's geometry and composition, such as blood vessel size and distribution, and perfusion. Relevant anatomical and physiological properties are summarized and implemented toward the creation of a preliminary finger phantom. To create a preliminary finger phantom, we synthesized a high-compliance silicone matrix with scatterers for embedding flexible tubing and investigated the addition of these scatterers to novel 3D printing resins for optical property control without altering mechanical stability, streamlining the production of phantoms with biologically relevant characteristics. Phantom utility was demonstrated by applying dynamic, pressure waveforms to produce tube volume change and resultant photoplethysmography (PPG) signals. 3D printed phantoms achieved more biologically relevant conditions compared to molded phantoms. These preliminary results indicate that the phantoms show strong potential to be developed into tools for evaluating pulse oximetry performance. Gaps, recommendations, and strategies are presented for continued phantom development.
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Affiliation(s)
- Andres J. Rodriguez
- Department of Biomedical Engineering, Florida International University, Miami. Florida, 33174, USA
| | - Sandhya Vasudevan
- Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Masoud Farahmand
- Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Sandy Weininger
- Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - William C. Vogt
- Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Christopher G. Scully
- Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Jessica Ramella-Roman
- Department of Biomedical Engineering, Florida International University, Miami. Florida, 33174, USA
| | - T. Joshua Pfefer
- Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993, USA
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Grygoryev K, Lu H, Sørensen S, Talebi Varnosfaderani O, Georgel R, Li L, Burke R, Andersson-Engels S. Miniature, multi-dichroic instrument for measuring the concentration of multiple fluorophores. BIOMEDICAL OPTICS EXPRESS 2024; 15:2377-2391. [PMID: 38633072 PMCID: PMC11019676 DOI: 10.1364/boe.516574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 03/05/2024] [Accepted: 03/06/2024] [Indexed: 04/19/2024]
Abstract
Identification of tumour margins during resection of the brain is critical for improving the post-operative outcomes. Due to the highly infiltrative nature of glioblastoma multiforme (GBM) and limited intraoperative visualization of the tumour margin, incomplete surgical resection has been observed to occur in up to 80 % of GBM cases, leading to nearly universal tumour recurrence and overall poor prognosis of 14.6 months median survival. This research presents a miniaturized, SiPMT-based optical system for simultaneous measurement of powerful DRS and weak auto-fluorescence for brain tumour detection. The miniaturisation of the optical elements confined the spatial separation of eight select wavelengths into footprint measuring 1.5 × 2 × 16 mm. The small footprint enables this technology to be integrated with existing surgical guidance instruments in the operating room. It's dynamic ability to subtract any background illumination and measure signal intensities across a broad range from pW to mWs make this design much more suitable for clinical environments as compared to spectrometer-based systems with limited dynamic ranges and high integration times. Measurements using optical tissue phantoms containing mixed fluorophores demonstrate correlation coefficients between the fitted response and actual concentration using PLS regression being 0.95, 0.87 and 0.97 for NADH, FAD and PpIX , respectively. These promising results indicate that our proposed miniaturized instrument could serve as an effective alternative in operating rooms, assisting surgeons in identifying brain tumours to achieving positive surgical outcomes for patients.
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Affiliation(s)
| | - Huihui Lu
- Tyndall National Institute, Lee Maltings Complex, Dyke Parade, Cork, Ireland
| | - Simon Sørensen
- Tyndall National Institute, Lee Maltings Complex, Dyke Parade, Cork, Ireland
| | | | - Rachel Georgel
- Tyndall National Institute, Lee Maltings Complex, Dyke Parade, Cork, Ireland
| | - Liyao Li
- Tyndall National Institute, Lee Maltings Complex, Dyke Parade, Cork, Ireland
| | - Ray Burke
- Tyndall National Institute, Lee Maltings Complex, Dyke Parade, Cork, Ireland
| | - Stefan Andersson-Engels
- Tyndall National Institute, Lee Maltings Complex, Dyke Parade, Cork, Ireland
- Department of Physics, University College Cork, College Road, Cork, Ireland
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Yang M, Wei Y, Reineck P, Ebendorff-Heidepriem H, Li J, McLaughlin RA. Development of a glass-based imaging phantom to model the optical properties of human tissue. BIOMEDICAL OPTICS EXPRESS 2024; 15:346-359. [PMID: 38223187 PMCID: PMC10783914 DOI: 10.1364/boe.504774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/30/2023] [Accepted: 12/03/2023] [Indexed: 01/16/2024]
Abstract
The fabrication of a stable, reproducible optical imaging phantom is critical to the assessment and optimization of optical imaging systems. We demonstrate the use of an alternative material, glass, for the development of tissue-mimicking phantoms. The glass matrix was doped with nickel ions to approximate the absorption of hemoglobin. Scattering levels representative of human tissue were induced in the glass matrix through controlled crystallization at elevated temperatures. We show that this type of glass is a viable material for creating tissue-mimicking optical phantoms by providing controlled levels of scattering and absorption with excellent optical homogeneity, long-term stability and reproducibility.
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Affiliation(s)
- Mingze Yang
- School of Biomedicine, The University of Adelaide, Adelaide, SA, Australia
- Institute for Photonics and Advanced Sensing, The University of Adelaide, Adelaide, SA, Australia
| | - Yunle Wei
- Institute for Photonics and Advanced Sensing, The University of Adelaide, Adelaide, SA, Australia
- School of Physics, Chemistry and Earth Sciences, The University of Adelaide, Adelaide, SA, Australia
| | - Philipp Reineck
- School of Science, RMIT University, Melbourne, VIC, Australia
| | - Heike Ebendorff-Heidepriem
- Institute for Photonics and Advanced Sensing, The University of Adelaide, Adelaide, SA, Australia
- School of Physics, Chemistry and Earth Sciences, The University of Adelaide, Adelaide, SA, Australia
| | - Jiawen Li
- Institute for Photonics and Advanced Sensing, The University of Adelaide, Adelaide, SA, Australia
- School of Electrical and Mechanical Engineering, The University of Adelaide, Adelaide, SA, Australia
| | - Robert A. McLaughlin
- School of Biomedicine, The University of Adelaide, Adelaide, SA, Australia
- Institute for Photonics and Advanced Sensing, The University of Adelaide, Adelaide, SA, Australia
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Gautam R, Mac Mahon D, Eager G, Ma H, Guadagno CN, Andersson-Engels S, Konugolu Venkata Sekar S. Fabrication and characterization of multi-biomarker optimized tissue-mimicking phantoms for multi-modal optical spectroscopy. Analyst 2023; 148:4768-4776. [PMID: 37665320 DOI: 10.1039/d3an00680h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Rapid advancement of novel optical spectroscopy and imaging systems relies on the availability of well-characterised and reproducible protocols for phantoms as a standard for the validation of the technique. The tissue-mimicking phantoms are also used to investigate photon transport in biological samples before clinical trials that require well-characterized phantoms with known optical properties (reduced scattering (μ's) and absorption (μa) coefficients). However, at present, there is limited literature available providing well-characterized phantom recipes considering various biomarkers and tested over a wide range of optical properties covering most of the human organs and applicable to multimodal optical spectroscopy. In this study, gelatin-based phantoms were designed to simulate tissue optical properties where India ink and Intralipid were used as absorbing and scattering agents, respectively. Multiple biomarkers were simulated by varying the gelatin concentration to mimic the change in tissue hydration and hydroxyapatite concentration to mimic bone signature. The recipe along with biomarkers were optimized and characterised over a wide range of optical properties (μa from 0.1 to 0.5 cm-1; μ's from 5 to 15 cm-1) relevant to human tissue using a broadband time-domain diffuse optical spectrometer. The data collected showed a linear relationship between the concentration of ink/lipids and μa/μ's values with negligible coupling between μa and μ's values. While being stored in a refrigerator post-fabrication, the μa and μ's did not change significantly (<4% coefficient of variation, 'CV') over three weeks. The reproducibility in three different sets was validated experimentally and found to be strong with a variation of ≤6% CV in μa and ≤9% CV in μ's. From the 3 × 3 data of μa and μ's matrices, one can deduce the recipe for any target absorption or reduced scattering coefficient. The applicability of the phantoms was tested using diffuse reflectance and Raman spectrometers. A use case application was demonstrated for Raman spectroscopy where hydration and hydroxyapatite phantoms were designed to characterize the Raman instrument. The Raman instrument could detect the change in 1% of HA and 5% of hydration. This study presents a first-of-its-kind robust, well-characterized, multi-biomarker phantom recipe for calibration and benchmarking of multimodal spectroscopy devices assisting in their clinical translation.
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Affiliation(s)
- Rekha Gautam
- Biophotonics@Tyndall, IPIC, Tyndall National Institute, T12 R5CP Cork, Ireland.
| | | | - Gráinne Eager
- School of Physics, Trinity College Dublin, Dublin 2, Ireland
| | - Hui Ma
- Biophotonics@Tyndall, IPIC, Tyndall National Institute, T12 R5CP Cork, Ireland.
| | | | - Stefan Andersson-Engels
- Biophotonics@Tyndall, IPIC, Tyndall National Institute, T12 R5CP Cork, Ireland.
- Department of Physics, University College Cork, T12 K8AF Cork, Ireland
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Sudakou A, Wabnitz H, Liemert A, Wolf M, Liebert A. Two-layered blood-lipid phantom and method to determine absorption and oxygenation employing changes in moments of DTOFs. BIOMEDICAL OPTICS EXPRESS 2023; 14:3506-3531. [PMID: 37497481 PMCID: PMC10368065 DOI: 10.1364/boe.492168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/29/2023] [Accepted: 05/29/2023] [Indexed: 07/28/2023]
Abstract
Near-infrared spectroscopy (NIRS) is an established technique for measuring tissue oxygen saturation (StO2), which is of high clinical value. For tissues that have layered structures, it is challenging but clinically relevant to obtain StO2 of the different layers, e.g. brain and scalp. For this aim, we present a new method of data analysis for time-domain NIRS (TD-NIRS) and a new two-layered blood-lipid phantom. The new analysis method enables accurate determination of even large changes of the absorption coefficient (Δµa) in multiple layers. By adding Δµa to the baseline µa, this method provides absolute µa and hence StO2 in multiple layers. The method utilizes (i) changes in statistical moments of the distributions of times of flight of photons (DTOFs), (ii) an analytical solution of the diffusion equation for an N-layered medium, (iii) and the Levenberg-Marquardt algorithm (LMA) to determine Δµa in multiple layers from the changes in moments. The method is suitable for NIRS tissue oximetry (relying on µa) as well as functional NIRS (fNIRS) applications (relying on Δµa). Experiments were conducted on a new phantom, which enabled us to simulate dynamic StO2 changes in two layers for the first time. Two separate compartments, which mimic superficial and deep layers, hold blood-lipid mixtures that can be deoxygenated (using yeast) and oxygenated (by bubbling oxygen) independently. Simultaneous NIRS measurements can be performed on the two-layered medium (variable superficial layer thickness, L), the deep (homogeneous), and/or the superficial (homogeneous). In two experiments involving ink, we increased the nominal µa in one of two compartments from 0.05 to 0.25 cm-1, L set to 14.5 mm. In three experiments involving blood (L set to 12, 15, or 17 mm), we used a protocol consisting of six deoxygenation cycles. A state-of-the-art multi-wavelength TD-NIRS system measured simultaneously on the two-layered medium, as well as on the deep compartment for a reference. The new method accurately determined µa (and hence StO2) in both compartments. The method is a significant progress in overcoming the contamination from the superficial layer, which is beneficial for NIRS and fNIRS applications, and may improve the determination of StO2 in the brain from measurements on the head. The advanced phantom may assist in the ongoing effort towards more realistic standardized performance tests in NIRS tissue oximetry. Data and MATLAB codes used in this study were made publicly available.
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Affiliation(s)
- Aleh Sudakou
- Nałęcz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Warsaw, Poland
| | - Heidrun Wabnitz
- Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany
| | - André Liemert
- Institut für Lasertechnologien in der Medizin und Meßtechnik an der Universität Ulm, Germany
| | - Martin Wolf
- Department of Neonatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Adam Liebert
- Nałęcz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Warsaw, Poland
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Jenne S, Zappe H. Multiwavelength tissue-mimicking phantoms with tunable vessel pulsation. JOURNAL OF BIOMEDICAL OPTICS 2023; 28:045003. [PMID: 37077500 PMCID: PMC10109273 DOI: 10.1117/1.jbo.28.4.045003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 03/26/2023] [Indexed: 05/03/2023]
Abstract
Significance For the development and routine characterization of optical devices used in medicine, tissue-equivalent phantoms mimicking a broad spectrum of human skin properties are indispensable. Aim Our work aims to develop a tissue-equivalent phantom suitable for photoplethysmography applications. The phantom includes the optical and mechanical properties of the three uppermost human skin layers (dermis, epidermis, and hypodermis, each containing different types of blood vessels) plus the ability to mimic pulsation. Approach While the mechanical properties of the polydimethylsiloxane base material are adjusted by different mixing ratios of a base and curing agent, the optical properties are tuned by adding titanium dioxide particles, India ink, and synthetic melanin in different concentrations. The layered structure of the phantom is realized using a doctor blade technique, and blood vessels are fabricated using molding wires of different diameters. The tissue-mimicking phantom is then integrated into an artificial circulatory system employing piezo-actuated double diaphragm pumps for testing. Results The optical and mechanical properties of human skin were successfully replicated. The diameter of the artificial blood vessels is linearly dependent on pump actuation, and the time-dependent expansion profile of real pulse forms were mimicked. Conclusions A tissue equivalent phantom suitable for the ex-vivo testing of opto-medical devices was demonstrated.
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Affiliation(s)
- Sophie Jenne
- University of Freiburg, Department of Microsystems Engineering—IMTEK, Gisela and Erwin Sick Chair of Micro-Optics, Freiburg, Germany
- Address all correspondence to Sophie Jenne,
| | - Hans Zappe
- University of Freiburg, Department of Microsystems Engineering—IMTEK, Gisela and Erwin Sick Chair of Micro-Optics, Freiburg, Germany
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Dumlupinar G, Venkata Sekar SK, Guadagno CN, Matias JS, Lanka P, Kho CK, Andersson-Engels S. Solid optical tissue phantom tools based on upconverting nanoparticles for biomedical applications. JOURNAL OF BIOMEDICAL OPTICS 2023; 28:036004. [PMID: 36915372 PMCID: PMC10006686 DOI: 10.1117/1.jbo.28.3.036004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 11/16/2022] [Indexed: 06/18/2023]
Abstract
SIGNIFICANCE Phantoms play a critical role in the development of biophotonics techniques. There is a lack of novel phantom tools in the emerging field of upconverting nanoparticles (UCNPs) for biophotonics application. This work provides a range of UCNP-based phantom tools and a manufacturing recipe to bridge the gap and accelerate the development of UCNP-based biophotonics applications. AIM The study aims to provide a well-characterized UCNP-based solid phantom recipe and set of phantom tools to address a wide range of UCNP-based biophotonics applications. APPROACH A solid phantom recipe based on silicone matrix was developed to manufacture UCNP-based phantoms. A lab built UCNP imaging system was used to characterize upconverted fluorescence emission of phantoms for linearity, homogeneity, and long-term stability. A photon time-of-flight spectroscopy technique was used to characterize the optical properties of the phantoms. RESULTS In total, 24 phantoms classified into 4 types, namely homogeneous, multilayer, inclusion, and base phantoms, were manufactured. The phantoms exhibit linear behavior over the dosage range of UCNPs. The phantoms were found to be stable over a limited observed period of 4 months with a coefficient of variation of < 4 % . The deep tissue imaging case showed that increasing the thickness of tissue reduced the UCNP emission. CONCLUSIONS A first-of-its-kind UCNP-based solid phantom recipe was developed, and four types of UCNP phantom tools to explore biophotonics applications were presented. The UCNP phantoms exhibited a linear behavior with dosage and were stable over time. An example case showed the potential use of the phantom for deep tissue imaging applications. With recent advance in the use of UCNPs for biophotonics, we believe our recipe and tools will play a pivotal role in the growth of the UCNPs for biophotonics applications.
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Affiliation(s)
- Gokhan Dumlupinar
- Tyndall National Institute, Biophotonics@Tyndall, IPIC, Cork, Ireland
- University College Cork, Department of Physics, Cork, Ireland
| | | | | | - Jean S. Matias
- Tyndall National Institute, Biophotonics@Tyndall, IPIC, Cork, Ireland
- University College Cork, Department of Physics, Cork, Ireland
| | - Pranav Lanka
- Tyndall National Institute, Biophotonics@Tyndall, IPIC, Cork, Ireland
| | - Chris K.W. Kho
- Tyndall National Institute, Biophotonics@Tyndall, IPIC, Cork, Ireland
| | - Stefan Andersson-Engels
- Tyndall National Institute, Biophotonics@Tyndall, IPIC, Cork, Ireland
- University College Cork, Department of Physics, Cork, Ireland
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Dinh J, Yamashita A, Kang H, Gioux S, Choi HS. Optical Tissue Phantoms for Quantitative Evaluation of Surgical Imaging Devices. ADVANCED PHOTONICS RESEARCH 2023; 4:2200194. [PMID: 36643020 PMCID: PMC9838008 DOI: 10.1002/adpr.202200194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Optical tissue phantoms (OTPs) have been extensively applied to the evaluation of imaging systems and surgical training. Due to their human tissue-mimicking characteristics, OTPs can provide accurate optical feedback on the performance of image-guided surgical instruments, simulating the biological sizes and shapes of human organs, and preserving similar haptic responses of original tissues. This review summarizes the essential components of OTPs (i.e., matrix, scattering and absorbing agents, and fluorophores) and the various manufacturing methods currently used to create suitable tissue-mimicking phantoms. As photobleaching is a major challenge in OTP fabrication and its feedback accuracy, phantom photostability and how the photobleaching phenomenon can affect their optical properties are discussed. Consequently, the need for novel photostable OTPs for the quantitative evaluation of surgical imaging devices is emphasized.
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Affiliation(s)
- Jason Dinh
- Gordon Center for Medical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Atsushi Yamashita
- Gordon Center for Medical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Homan Kang
- Gordon Center for Medical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Sylvain Gioux
- Intuitive Surgical Sàrl, 1170 Aubonne, Switzerland
- ICube Laboratory, University of Strasbourg, 67081 Strasbourg, France
| | - Hak Soo Choi
- Gordon Center for Medical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Boston, MA 02114, USA
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Gunther JE, Jayet B, Sekar SKV, Kainerstorfer JM, Andersson-Engels S. Review of optical methods for fetal monitoring in utero. JOURNAL OF BIOPHOTONICS 2022; 15:e202100343. [PMID: 35285153 DOI: 10.1002/jbio.202100343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 02/15/2022] [Accepted: 03/11/2022] [Indexed: 06/14/2023]
Abstract
The current technology for monitoring fetal wellbeing during child birth is cardiotocography. However, CTG has high false positive rates that lead to unnecessary emergency Cesarean deliveries and false negatives that result in birth injuries. To curtail these issues, fetal pulse oximetery has been a topic of interest for many decades. Fetal pulse oximetry would yield the oxygen saturation of the fetus in utero and provide a more robust marker for clinicians to make decisions about performing emergency Cesarean deliveries. Here, we present a review of biomedical optical developments related to transabdominal fetal pulse oximetery in the biophotonics field and the challenges that must be overcome to make transabdominal pulse oximetry a clinical reality.
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Affiliation(s)
| | - Baptiste Jayet
- Tyndall National Institute, University College Cork, Cork, Ireland
| | | | - Jana M Kainerstorfer
- Department of Biomedical Engineering, Carnegie Mellon University, Pennsylvania, USA
| | - Stefan Andersson-Engels
- Tyndall National Institute, University College Cork, Cork, Ireland
- Department of Physics, University College Cork, Cork, Ireland
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Allgaier M, Smith BJ. Smartphone-based measurements of the optical properties of snow. APPLIED OPTICS 2022; 61:4429-4436. [PMID: 36256281 DOI: 10.1364/ao.457976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 04/30/2022] [Indexed: 06/16/2023]
Abstract
Snow is a highly complex medium composed of ice crystals of various shapes and sizes. Knowledge of its intrinsic optical properties such as scattering and absorption coefficients is tantamount to radiative transfer models in climate research. The absorption coefficient, in particular, allows us to access information about light-absorbing particles contained in the snow. In contrast to snow's apparent properties such as the albedo, measuring the intrinsic properties is challenging. Here, we present a simple apparatus that can measure bulk optical properties of snow using readily available components and a smartphone camera, and a robust diffuse-optical framework for data analysis. We demonstrate the instrument both on scattering phantoms with known scattering and absorption coefficients and in the field. Its low cost, simplicity, and portability uniquely qualify this setup for large-scale field work, undergraduate education, and citizen science.
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Hacker L, Wabnitz H, Pifferi A, Pfefer TJ, Pogue BW, Bohndiek SE. Criteria for the design of tissue-mimicking phantoms for the standardization of biophotonic instrumentation. Nat Biomed Eng 2022; 6:541-558. [PMID: 35624150 DOI: 10.1038/s41551-022-00890-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Accepted: 02/07/2022] [Indexed: 01/08/2023]
Abstract
A lack of accepted standards and standardized phantoms suitable for the technical validation of biophotonic instrumentation hinders the reliability and reproducibility of its experimental outputs. In this Perspective, we discuss general criteria for the design of tissue-mimicking biophotonic phantoms, and use these criteria and state-of-the-art developments to critically review the literature on phantom materials and on the fabrication of phantoms. By focusing on representative examples of standardization in diffuse optical imaging and spectroscopy, fluorescence-guided surgery and photoacoustic imaging, we identify unmet needs in the development of phantoms and a set of criteria (leveraging characterization, collaboration, communication and commitment) for the standardization of biophotonic instrumentation.
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Affiliation(s)
- Lina Hacker
- Department of Physics, University of Cambridge, Cambridge, UK.,Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
| | - Heidrun Wabnitz
- Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany
| | | | | | - Brian W Pogue
- Thayer School of Engineering, Dartmouth, Hanover, NH, USA
| | - Sarah E Bohndiek
- Department of Physics, University of Cambridge, Cambridge, UK. .,Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK.
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Goldfain AM, Lemaillet P, Allen DW, Briggman KA, Hwang J. Polydimethylsiloxane tissue-mimicking phantoms with tunable optical properties. JOURNAL OF BIOMEDICAL OPTICS 2021; 27:JBO-210209SSRR. [PMID: 34796707 PMCID: PMC8601433 DOI: 10.1117/1.jbo.27.7.074706] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 10/25/2021] [Indexed: 05/05/2023]
Abstract
SIGNIFICANCE The polymer, polydimethylsiloxane (PDMS), has been increasingly used to make tissue simulating phantoms due to its excellent processability, durability, flexibility, and limited tunability of optical, mechanical, and thermal properties. We report on a robust technique to fabricate PDMS-based tissue-mimicking phantoms where the broad range of scattering and absorption properties are independently adjustable in the visible- to near-infrared wavelength range from 500 to 850 nm. We also report on an analysis method to concisely quantify the phantoms' broadband characteristics with four parameters. AIM We report on techniques to manufacture and characterize solid tissue-mimicking phantoms of PDMS polymers. Tunability of the absorption (μa ( λ ) ) and reduced scattering coefficient spectra (μs'(λ)) in the wavelength range of 500 to 850 nm is demonstrated by adjusting the concentrations of light absorbing carbon black powder (CBP) and light scattering titanium dioxide powder (TDP) added into the PDMS base material. APPROACH The μa ( λ ) and μs'(λ) of the phantoms were obtained through measurements with a broadband integrating sphere system and by applying an inverse adding doubling algorithm. Analyses of μa ( λ ) and μs'(λ) of the phantoms, by fitting them to linear and power law functions, respectively, demonstrate that independent control of μa ( λ ) and μs'(λ) is possible by systematically varying the concentrations of CBP and TDP. RESULTS Our technique quantifies the phantoms with four simple fitting parameters enabling a concise tabulation of their broadband optical properties as well as comparisons to the optical properties of biological tissues. We demonstrate that, to a limited extent, the scattering properties of our phantoms mimic those of human tissues of various types. A possible way to overcome this limitation is demonstrated with phantoms that incorporate polystyrene microbead scatterers. CONCLUSIONS Our manufacturing and analysis techniques may further promote the application of PDMS-based tissue-mimicking phantoms and may enable robust quality control and quality checks of the phantoms.
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Affiliation(s)
- Aaron M. Goldfain
- National Institute of Standards and Technology, Sensor Science Division, Gaithersburg, Maryland, United States
| | - Paul Lemaillet
- National Institute of Standards and Technology, Sensor Science Division, Gaithersburg, Maryland, United States
| | - David W. Allen
- National Institute of Standards and Technology, Sensor Science Division, Gaithersburg, Maryland, United States
| | - Kimberly A. Briggman
- National Institute of Standards and Technology, Applied Physics Division, Boulder, Colorado, United States
| | - Jeeseong Hwang
- National Institute of Standards and Technology, Applied Physics Division, Boulder, Colorado, United States
- Address all correspondence to Jeeseong Hwang,
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Rogelj L, Simončič U, Tomanič T, Jezeršek M, Pavlovčič U, Stergar J, Milanič M. Effect of curvature correction on parameters extracted from hyperspectral images. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:JBO-210189R. [PMID: 34490762 PMCID: PMC8420878 DOI: 10.1117/1.jbo.26.9.096003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 08/23/2021] [Indexed: 06/13/2023]
Abstract
SIGNIFICANCE Hyperspectral imaging (HSI) has emerged as a promising optical technique. Besides optical properties of a sample, other sample physical properties also affect the recorded images. They are significantly affected by the sample curvature and sample surface to camera distance. A correction method to reduce the artifacts is necessary to reliably extract sample properties. AIM Our aim is to correct hyperspectral images using the three-dimensional (3D) surface data and assess how the correction affects the extracted sample properties. APPROACH We propose the combination of HSI and 3D profilometry to correct the images using the Lambert cosine law. The feasibility of the correction method is presented first on hemispherical tissue phantoms and next on human hands before, during, and after the vascular occlusion test (VOT). RESULTS Seven different phantoms with known optical properties were created and imaged with a hyperspectral system. The correction method worked up to 60 deg inclination angle, whereas for uncorrected images the maximum angles were 20 deg. Imaging hands before, during, and after VOT shows good agreement between the expected and extracted skin physiological parameters. CONCLUSIONS The correction method was successfully applied on the images of tissue phantoms of known optical properties and geometry and VOT. The proposed method could be applied to any reflectance optical imaging technique and should be used whenever the sample parameters need to be extracted from a curved surface sample.
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Affiliation(s)
- Luka Rogelj
- University of Ljubljana, Faculty of Mathematics and Physics, Ljubljana, Slovenia
| | - Urban Simončič
- University of Ljubljana, Faculty of Mathematics and Physics, Ljubljana, Slovenia
- Jozef Stefan Institute, Ljubljana, Slovenia
| | - Tadej Tomanič
- University of Ljubljana, Faculty of Mathematics and Physics, Ljubljana, Slovenia
| | - Matija Jezeršek
- University of Ljubljana, Faculty of Mechanical Engineering, Ljubljana, Slovenia
| | - Urban Pavlovčič
- University of Ljubljana, Faculty of Mechanical Engineering, Ljubljana, Slovenia
| | | | - Matija Milanič
- University of Ljubljana, Faculty of Mathematics and Physics, Ljubljana, Slovenia
- Jozef Stefan Institute, Ljubljana, Slovenia
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Mosca S, Dey P, Salimi M, Gardner B, Palombo F, Stone N, Matousek P. Estimating the Reduced Scattering Coefficient of Turbid Media Using Spatially Offset Raman Spectroscopy. Anal Chem 2021; 93:3386-3392. [DOI: 10.1021/acs.analchem.0c04290] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Sara Mosca
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, UK Research and Innovation, Harwell Campus, Didcot OX11 0QX, United Kingdom
| | - Priyanka Dey
- School of Physics and Astronomy, University of Exeter, Exeter EX4 4QL, United Kingdom
| | - Marzieh Salimi
- School of Physics and Astronomy, University of Exeter, Exeter EX4 4QL, United Kingdom
| | - Benjamin Gardner
- School of Physics and Astronomy, University of Exeter, Exeter EX4 4QL, United Kingdom
| | - Francesca Palombo
- School of Physics and Astronomy, University of Exeter, Exeter EX4 4QL, United Kingdom
| | - Nick Stone
- School of Physics and Astronomy, University of Exeter, Exeter EX4 4QL, United Kingdom
| | - Pavel Matousek
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, UK Research and Innovation, Harwell Campus, Didcot OX11 0QX, United Kingdom
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Yücel MA, Lühmann AV, Scholkmann F, Gervain J, Dan I, Ayaz H, Boas D, Cooper RJ, Culver J, Elwell CE, Eggebrecht A, Franceschini MA, Grova C, Homae F, Lesage F, Obrig H, Tachtsidis I, Tak S, Tong Y, Torricelli A, Wabnitz H, Wolf M. Best practices for fNIRS publications. NEUROPHOTONICS 2021; 8:012101. [PMID: 33442557 PMCID: PMC7793571 DOI: 10.1117/1.nph.8.1.012101] [Citation(s) in RCA: 115] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 12/02/2020] [Indexed: 05/09/2023]
Abstract
The application of functional near-infrared spectroscopy (fNIRS) in the neurosciences has been expanding over the last 40 years. Today, it is addressing a wide range of applications within different populations and utilizes a great variety of experimental paradigms. With the rapid growth and the diversification of research methods, some inconsistencies are appearing in the way in which methods are presented, which can make the interpretation and replication of studies unnecessarily challenging. The Society for Functional Near-Infrared Spectroscopy has thus been motivated to organize a representative (but not exhaustive) group of leaders in the field to build a consensus on the best practices for describing the methods utilized in fNIRS studies. Our paper has been designed to provide guidelines to help enhance the reliability, repeatability, and traceability of reported fNIRS studies and encourage best practices throughout the community. A checklist is provided to guide authors in the preparation of their manuscripts and to assist reviewers when evaluating fNIRS papers.
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Affiliation(s)
- Meryem A. Yücel
- Boston University, Neurophotonics Center, Biomedical Engineering, Boston, Massachusetts, United States
- Massachusetts General Hospital, Harvard Medical School, MGH/HST Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
- Address all correspondence to Meryem A. Yücel,
| | - Alexander v. Lühmann
- Boston University, Neurophotonics Center, Biomedical Engineering, Boston, Massachusetts, United States
- Massachusetts General Hospital, Harvard Medical School, MGH/HST Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
| | - Felix Scholkmann
- University Hospital Zurich, University of Zurich, Department of Neonatology, Biomedical Optics Research Laboratory, Neonatology Research, Zurich, Switzerland
- University of Bern, Institute for Complementary and Integrative Medicine, Bern, Switzerland
| | - Judit Gervain
- Université de Paris, CNRS, Integrative Neuroscience and Cognition Center, Paris, France
- Università di Padova, Department of Social and Developmental Psychology, Padua, Italy
| | - Ippeita Dan
- Chuo University, Faculty of Science and Engineering, Applied Cognitive Neuroscience Laboratory, Tokyo, Japan
| | - Hasan Ayaz
- Drexel University, School of Biomedical Engineering, Science and Health Systems, Philadelphia, Pennsylvania, United States
- Drexel University, College of Arts and Sciences, Department of Psychology, Philadelphia, Pennsylvania, United States
- Drexel University, Drexel Solutions Institute, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, Department of Family and Community Health, Philadelphia, Pennsylvania, United States
- Children’s Hospital of Philadelphia, Center for Injury Research and Prevention, Philadelphia, Pennsylvania, United States
| | - David Boas
- Boston University, Neurophotonics Center, Biomedical Engineering, Boston, Massachusetts, United States
| | - Robert J. Cooper
- University College London, DOT-HUB, Department of Medical Physics and Biomedical Engineering, Biomedical Optics Research Laboratory, London, United Kingdom
| | - Joseph Culver
- Washington University School of Medicine, Department of Radiology, St. Louis, Missouri, United States
| | - Clare E. Elwell
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Adam Eggebrecht
- Washington University School of Medicine, Mallinckrodt Institute of Radiology, St. Louis, Missouri, United States
| | - Maria A. Franceschini
- Massachusetts General Hospital, Harvard Medical School, MGH/HST Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States
| | - Christophe Grova
- Concordia University, Department of Physics and PERFORM Centre, Multimodal Functional Imaging Lab, Montreal, Québec, Canada
- McGill University, Biomedical Engineering Department, Multimodal Functional Imaging Lab, Montreal, Québec, Canada
| | - Fumitaka Homae
- Tokyo Metropolitan University, Department of Language Sciences, Tokyo, Japan
| | - Frédéric Lesage
- Polytechnique Montréal, Department Electrical Engineering, Montreal, Canada
| | - Hellmuth Obrig
- University Hospital Leipzig, Max-Planck-Institute for Human Cognitive and Brain Sciences and Clinic for Cognitive Neurology, Leipzig, Germany
| | - Ilias Tachtsidis
- University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Sungho Tak
- Korea Basic Science Institute, Research Center for Bioconvergence Analysis, Ochang, Cheongju, Republic of Korea
| | - Yunjie Tong
- Weldon School of Biomedical Engineering Purdue University, West Lafayette, Indiana, United States
| | - Alessandro Torricelli
- Politecnico di Milano, Dipartimento di Fisica, Milan, Italy
- Consiglio Nazionale delle Ricerche, Istituto di Fotonica e Nanotecnologie, Milan, Italy
| | | | - Martin Wolf
- University Hospital Zurich, University of Zurich, Department of Neonatology, Biomedical Optics Research Laboratory, Neonatology Research, Zurich, Switzerland
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Baez-Castillo L, Ortiz-Rascón E, Bruce NC, Garduño-Mejía J, Carrillo-Torres RC, Álvarez-Ramos ME. Merging Mie solutions and the radiative transport equation to measure optical properties of scattering particles in optical phantoms. APPLIED OPTICS 2020; 59:10591-10598. [PMID: 33361994 DOI: 10.1364/ao.403388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 10/27/2020] [Indexed: 06/12/2023]
Abstract
We present a new method to calculate the complex refractive index of spherical scatterers in a novel optical phantom developed by using homemade monodisperse silica nanospheres embedded into a polyester resin matrix and an ethanol-water mixture for applications in diffuse imaging. The spherical geometry of these nanoparticles makes them suitable for direct comparison between the values of the absorption and reduced scattering coefficients (μa and μs', respectively) obtained by the diffusion approximation solution to the transport equation from scattering measurements and those obtained by the Mie solution to Maxwell's equations. The values of the optical properties can be obtained by measuring, using an ultrafast detector, the time-resolved intensity distribution profiles of diffuse light transmitted through a thick slab of the silica nanosphere phantom, and by fitting them to the time-dependent diffusion approximation solution to the transport equation. These values can also be obtained by Mie solutions for spherical particles when their physical properties and size are known. By using scanning electron microscopy, we measured the size of these nanospheres, and the numerical results of μa and μs' can then be inferred by calculating the absorption and scattering efficiencies. Then we propose a numerical interval for the imaginary part of the complex refractive index of SiO2 nanospheres, ns, which is estimated by fixing the fitted values of μa and μs', using the known value of the real part of ns, and finding the corresponding value of Im(ns) that matches the optical parameters obtained by both methods finding values close to those reported for silica glass. This opens the possibility of producing optical phantoms with scattering and absorption properties that can be predicted and designed from precise knowledge of the physical characteristics of their constituents from a microscopic point of view.
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Pacheco A, Li H, Chakravarty M, Sekar SKV, Andersson-Engels S. Anthropomorphic optical phantom of the neonatal thorax: a key tool for pulmonary studies in preterm infants. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:JBO-200122RR. [PMID: 33205636 PMCID: PMC7670093 DOI: 10.1117/1.jbo.25.11.115001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 10/21/2020] [Indexed: 05/08/2023]
Abstract
SIGNIFICANCE Gas in scattering media absorption spectroscopy (GASMAS) is a technique for gas sensing in cavities surrounded by scattering materials. GASMAS could be translated to the clinic to monitor lung function continuously and noninvasively in neonates. Accurate tissue phantoms are essential to assess the strengths and limitations of gas spectroscopy in gas-containing cavities in the human body. AIM The aim is to develop a detailed protocol to produce a long-lasting, multistructure tissue phantom of the thorax of a neonate. The phantom mimics the geometry and the optical properties of the main organs of the thorax and has an empty pulmonary cavity that facilitates GASMAS monitoring of gas content. APPROACH The anatomic geometry of heart, lungs, bones, muscle, fat, and skin was obtained from a neonatal computed tomography scan. Once segmented, organs were 3D printed and used to create negative rubber molds. The entire thorax was built in phantom material (silicone as matrix, black ink as absorber, and silica microspheres as scatters) by placing all phantom organs inside the muscle structure. Our phantom recipe was customized by mixing specific ratios of ink and spheres to match the optical properties of the different organs that were consider to be homogeneous. RESULTS An anthropomorphic thorax phantom with the desired optical properties (μa and μs') at 760 nm was built and used to obtain "transdermal" GASMAS measurements of oxygen content within the lung cavity. CONCLUSION A protocol to build a robust optical phantom of the thorax of a neonate was used to conduct benchtop studies. This recipe can be implemented to reproduce the geometry and optical properties of any human or animal tissue.
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Affiliation(s)
- Andrea Pacheco
- Tyndall National Institute, Biophotonics@Tyndall, Irish Photonic Integration Centre, Lee Maltings, Dyke Parade, Cork, Ireland
- University College Cork, Department of Physics, College Road, Cork, Ireland
| | - Haiyang Li
- Tyndall National Institute, Biophotonics@Tyndall, Irish Photonic Integration Centre, Lee Maltings, Dyke Parade, Cork, Ireland
| | - Monisha Chakravarty
- Tyndall National Institute, Biophotonics@Tyndall, Irish Photonic Integration Centre, Lee Maltings, Dyke Parade, Cork, Ireland
| | | | - Stefan Andersson-Engels
- Tyndall National Institute, Biophotonics@Tyndall, Irish Photonic Integration Centre, Lee Maltings, Dyke Parade, Cork, Ireland
- University College Cork, Department of Physics, College Road, Cork, Ireland
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18
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Naglič P, Zelinskyi Y, Rogelj L, Stergar J, Milanič M, Novak J, Kumperščak B, Bürmen M. Optical properties of PlatSil SiliGlass tissue-mimicking phantoms. BIOMEDICAL OPTICS EXPRESS 2020; 11:3753-3768. [PMID: 33014564 PMCID: PMC7510920 DOI: 10.1364/boe.391720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 05/08/2020] [Accepted: 06/05/2020] [Indexed: 06/11/2023]
Abstract
In this work, we revise the preparation procedure and conduct an in depth characterization of optical properties for the recently proposed silicone-based tissue-mimicking optical phantoms in the spectral range from 475 to 925 nm. The optical properties are characterized in terms of refractive index and its temperature dependence, absorption and reduced scattering coefficients and scattering phase function related quantifiers. The scattering phase function and related quantifiers of the optical phantoms are first assessed within the framework of the Mie theory by using the measured refractive index of SiliGlass and size distribution of the hollow silica spherical particles that serve as scatterers. A set of purely absorbing optical phantoms in cuvettes is used to evaluate the linearity of the absorption coefficient with respect to the concentration of black pigment that serves as the absorber. Finally, the optical properties in terms of the absorption and reduced scattering coefficients and the subdiffusive scattering phase function quantifier γ are estimated for a subset of phantoms from spatially resolved reflectance using deep learning aided inverse models. To this end, an optical fiber probe with six linearly arranged optical fibers is used to collect the backscattered light at small and large distances from the source fiber. The underlying light propagation modeling is based on the stochastic Monte Carlo method that accounts for all the details of the optical fiber probe.
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Affiliation(s)
- Peter Naglič
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Yevhen Zelinskyi
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Luka Rogelj
- University of Ljubljana, Faculty of Mathematics and Physics, Jadranska ulica 19, 1000 Ljubljana, Slovenia
| | - Jošt Stergar
- University of Ljubljana, Faculty of Mathematics and Physics, Jadranska ulica 19, 1000 Ljubljana, Slovenia
| | - Matija Milanič
- University of Ljubljana, Faculty of Mathematics and Physics, Jadranska ulica 19, 1000 Ljubljana, Slovenia
- Jozef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia
| | - Jure Novak
- Dia-Vit d.o.o., Litijska cesta 186e, 1000 Ljubljana, Slovenia
| | | | - Miran Bürmen
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
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Naglič P, Zelinskyi Y, Likar B, Bürmen M. Determination of refractive index, size, and solid content of monodisperse polystyrene microsphere suspensions for the characterization of optical phantoms. BIOMEDICAL OPTICS EXPRESS 2020; 11:1901-1918. [PMID: 32341856 PMCID: PMC7173914 DOI: 10.1364/boe.387619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 02/20/2020] [Accepted: 02/24/2020] [Indexed: 06/11/2023]
Abstract
Monodisperse polystyrene microspheres are often utilized in optical phantoms since optical properties such as the scattering coefficient and the scattering phase function can be calculated using the Mie theory. However, the calculated values depend on the inherent physical parameters of the microspheres which include the size, refractive index, and solid content. These parameters are often provided only approximately or can be affected by long shelf times. We propose a simple method to obtain the values of these parameters by measuring the collimated transmission of polystyrene microsphere suspensions from which the wavelength-dependent scattering coefficient can be calculated using the Beer-Lambert law. Since a wavelength-dependent scattering coefficient of a single suspension is insufficient to uniquely derive the size, refractive index and solid content by the Mie theory, the crucial and novel step involves suspending the polystyrene microspheres in aqueous sucrose solutions with different sucrose concentrations that modulates the refractive index of the medium and yields several wavelength-dependent scattering coefficients. With the proposed method, we are able to obtain the refractive index within 0.2% in the wavelength range from 500 to 800 nm, the microsphere size to approximately 15 nm and solid content within 2% of their respective reference values.
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20
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Stergar J, Dolenec R, Kojc N, Lakota K, Perše M, Tomšič M, Milanic M. Hyperspectral evaluation of peritoneal fibrosis in mouse models. BIOMEDICAL OPTICS EXPRESS 2020; 11:1991-2006. [PMID: 32341862 PMCID: PMC7173895 DOI: 10.1364/boe.387837] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 02/19/2020] [Accepted: 02/26/2020] [Indexed: 05/11/2023]
Abstract
Analysis of morphological changes of the peritoneal membrane is an essential part of animal studies when investigating molecular mechanisms involved in the development of peritoneal fibrosis or testing the effects of potential therapeutic agents. Current methods, such as histology and immunohistochemistry, require time consuming sample processing and analysis and result in limited spatial information. In this paper we present a new method to evaluate structural and chemical changes in an animal model of peritoneal fibrosis that is based on hyperspectral imaging and a model of light transport. The method is able to distinguish between healthy and diseased subjects based on morphological as well as physiological parameters such as blood and scattering parameters. Furthermore, it enables evaluation of changes, such as degree of inflammation and fibrosis, that are closely related to histological findings.
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Affiliation(s)
- Jošt Stergar
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska ulica 19, 1000 Ljubljana, Slovenia
| | - Rok Dolenec
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska ulica 19, 1000 Ljubljana, Slovenia
- J. Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia
| | - Nika Kojc
- Faculty of Medicine,University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
| | - Katja Lakota
- University Medical Centre, Department of Rheumatology, Vodnikova ulica 62, 1000 Ljubljana, Slovenia
- FAMNIT, University of Primorska, Glagoljaska 8, 6000 Koper, Slovenia
| | - Martina Perše
- Faculty of Medicine,University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
| | - Matija Tomšič
- Faculty of Medicine,University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
- University Medical Centre, Department of Rheumatology, Vodnikova ulica 62, 1000 Ljubljana, Slovenia
| | - Matija Milanic
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska ulica 19, 1000 Ljubljana, Slovenia
- J. Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia
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Mosca S, Lanka P, Stone N, Konugolu Venkata Sekar S, Matousek P, Valentini G, Pifferi A. Optical characterization of porcine tissues from various organs in the 650-1100 nm range using time-domain diffuse spectroscopy. BIOMEDICAL OPTICS EXPRESS 2020; 11:1697-1706. [PMID: 32206436 PMCID: PMC7075607 DOI: 10.1364/boe.386349] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 02/14/2020] [Accepted: 02/14/2020] [Indexed: 05/10/2023]
Abstract
We present a systematic characterization of the optical properties (µa and µs') of nine representative ex vivo porcine tissues over a broadband spectrum (650-1100 nm). We applied time-resolved diffuse optical spectroscopy measurements for recovering the optical properties of porcine tissues depicting a realistic representation of the tissue heterogeneity and morphology likely to be found in different ex vivo tissues. The results demonstrate a large spectral and inter-tissue variation of optical properties. The data can be exploited for planning or simulating ex vivo experiments with various biophotonics techniques, or even to construct artificial structures mimicking specific pathologies exploiting the wide assortment in optical properties.
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Affiliation(s)
- Sara Mosca
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, UK Research and Innovation, Harwell Campus, OX11 0QX, United Kingdom
- These authors contributed equally to this research
| | - Pranav Lanka
- Dipartimento di Fisica, Politecnico di Milano, Milano, Italy
- These authors contributed equally to this research
| | - Nick Stone
- School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, United Kingdom
| | | | - Pavel Matousek
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, UK Research and Innovation, Harwell Campus, OX11 0QX, United Kingdom
| | - Gianluca Valentini
- Dipartimento di Fisica, Politecnico di Milano, Milano, Italy
- Consiglio Nazionale delle Ricerche, Istituto di Fotonica e Nanotecnologie, Milano, Italy
| | - Antonio Pifferi
- Dipartimento di Fisica, Politecnico di Milano, Milano, Italy
- Consiglio Nazionale delle Ricerche, Istituto di Fotonica e Nanotecnologie, Milano, Italy
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Broadband Time Domain Diffuse Optical Reflectance Spectroscopy: A Review of Systems, Methods, and Applications. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9245465] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
This review presents recent developments and a wide overview of broadband time domain diffuse optical spectroscopy (TD-DOS). Various topics including physics of photon migration, advanced instrumentation, methods of analysis, applications covering multiple domains (tissue chromophore, in vivo studies, food, wood, pharmaceutical industry) are elaborated. The key role of standardization and recent studies in that direction are discussed. Towards the end, a brief outlook is presented on the current status and future trends in broadband TD-DOS.
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