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Xu K, Arbab MH. Terahertz polarimetric imaging of biological tissue: Monte Carlo modeling of signal contrast mechanisms due to Mie scattering. Biomed Opt Express 2024; 15:2328-2342. [PMID: 38633080 PMCID: PMC11019684 DOI: 10.1364/boe.515623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 02/16/2024] [Accepted: 02/27/2024] [Indexed: 04/19/2024]
Abstract
Many promising biomedical applications have been proposed for terahertz (THz) spectroscopy and diagnostic imaging techniques. Polarimetric imaging systems are generally useful for enhancing imaging contrasts, yet the interplay between THz polarization changes and the random discrete structures in biological samples is not well understood. In this work, we performed Monte Carlo simulations of the propagation of polarized THz waves in skin and adipose tissues based on the Mie scattering from intrinsic structures, such as hair follicles or sweat glands. We show that the polarimetric contrasts are distinctly affected by concentration, size and dielectric properties of the scatterers, as well as the frequency and polarization of the incident THz waves. We describe the experimental requirements for observing and extracting these polarimetric signals due to the low energy and small angular spread of the back-scattered THz radiation. We analyzed the spatially integrated Mueller matrices of samples in the normal-incidence back-scattering geometry. We show that the frequency-dependent degree of polarization (DOP) can be used to infer the concentrations and dielectric contents of the scattering structures. Our modeling approach can be used to inform the design of the imaging modalities and the interpretation of the spectroscopic data in future terahertz biomedical imaging applications.
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Affiliation(s)
- Kuangyi Xu
- Department of Biomedical Engineering, State University of New York at Stony Brook, Stony Brook, New York 11794, USA
| | - M. Hassan Arbab
- Department of Biomedical Engineering, State University of New York at Stony Brook, Stony Brook, New York 11794, USA
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Xu K, Arbab MH. Terahertz polarimetric imaging of biological tissues: Monte Carlo modeling of signal contrast mechanisms due to Mie scattering. Res Sq 2023:rs.3.rs-3745690. [PMID: 38168438 PMCID: PMC10760297 DOI: 10.21203/rs.3.rs-3745690/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Many promising biomedical applications have been proposed for terahertz (THz) spectroscopy and diagnostic imaging techniques. Polarimetric imaging systems are generally useful for enhancing imaging contrasts, yet the interplay between THz polarization changes and the random discrete structures in biological samples are not well understood. In this work, we performed Monte Carlo simulations of the propagation of polarized THz waves in skin and adipose tissues based on the Mie scattering from intrinsic structures, such as hair follicles or sweat glands. We show that the polarimetric contrasts are distinctly affected by concentration, size and dielectric properties of the scatterers, as well as the frequency and polarization of the incident THz waves. We describe the experimental requirements for observing and extracting these polarimetric signals due to the low energy and small angular spread of the back-scattered THz radiation. We analyzed the spatially integrated Mueller matrices of samples in the normal-incidence back-scattering geometry. We show that the frequency-dependent degree of polarization (DOP) can be used to infer the concentrations and dielectric contents of the scattering structures. Our modeling approach can be used to inform the design of the imaging modalities and the interpretation of the spectroscopic data in future terahertz biomedical imaging applications.
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Affiliation(s)
- Kuangyi Xu
- Department of Biomedical Engineering, State University of New York at Stony Brook, Stony Brook, New York 11794, USA
| | - M. Hassan Arbab
- Department of Biomedical Engineering, State University of New York at Stony Brook, Stony Brook, New York 11794, USA
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Virk AS, Harris ZB, Arbab MH. Design and characterization of a hyperbolic-elliptical lens pair in a rapid beam steering system for single-pixel terahertz spectral imaging of the cornea. Opt Express 2023; 31:39568-39582. [PMID: 38041275 DOI: 10.1364/oe.496894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 10/10/2023] [Indexed: 12/03/2023]
Abstract
Terahertz (THz) time-domain spectroscopy has been investigated for assessment of the hydration levels in the cornea, intraocular pressure, and changes in corneal topography. Previous efforts at THz imaging of the cornea have employed off-axis parabolic mirrors to achieve normal incidence along the spherical surface. However, this comes at the cost of an asymmetric field-of-view (FOV) and a long scan time because it requires raster-scanning of the collimated beam across the large mirror diameter. This paper proposes a solution by designing a pair of aspheric lenses that can provide a larger symmetric spherical FOV (9.6 mm) and reduce the scan time by two orders of magnitude using a novel beam-steering approach. A hyperbolic-elliptical lens was designed and optimized to achieve normal incidence and phase-front matching between the focused THz beam and the target curvature. The lenses were machined from a slab of high-density polyethylene and characterized in comparison to ray-tracing simulations by imaging several targets of similar sizes to the cornea. Our experimental results showed excellent agreement in the increased symmetric FOV and confirmed the reduction in scan time to about 3-4 seconds. In the future, this lens design process can be extended for imaging the sclera of the eye and other curved biological surfaces, such as the nose and fingers.
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Xue J, Zhang Y, Guang Z, Miao T, Ali Z, Qiao D, Yao Y, Wu K, Zhou L, Meng C, Copner N. Ultra-High Sensitivity Terahertz Microstructured Fiber Biosensor for Diabetes Mellitus and Coronary Heart Disease Marker Detection. Sensors (Basel) 2023; 23:2020. [PMID: 36850616 PMCID: PMC9962755 DOI: 10.3390/s23042020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/20/2023] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
Diabetes Mellitus (DM) and Coronary Heart Disease (CHD) are among top causes of patient health issues and fatalities in many countries. At present, terahertz biosensors have been widely used to detect chronic diseases because of their accurate detection, fast operation, flexible design and easy fabrication. In this paper, a Zeonex-based microstructured fiber (MSF) biosensor is proposed for detecting DM and CHD markers by adopting a terahertz time-domain spectroscopy system. A suspended hollow-core structure with a square core and a hexagonal cladding is used, which enhances the interaction of terahertz waves with targeted markers and reduces the loss. This work focuses on simulating the transmission performance of the proposed MSF sensor by using a finite element method and incorporating a perfectly matched layer as the absorption boundary. The simulation results show that this MSF biosensor exhibits an ultra-high relative sensitivity, especially up to 100.35% at 2.2THz, when detecting DM and CHD markers. Furthermore, for different concentrations of disease markers, the MSF exhibits significant differences in effective material loss, which can effectively improve clinical diagnostic accuracy and clearly distinguish the extent of the disease. This MSF biosensor is simple to fabricate by 3D printing and extrusion technologies, and is expected to provide a convenient and capable tool for rapid biomedical diagnosis.
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Affiliation(s)
- Jia Xue
- Department of Physics, School of Arts & Sciences, Shaanxi University of Science & Technology, Xi’an 710021, China
| | - Yani Zhang
- Department of Physics, School of Arts & Sciences, Shaanxi University of Science & Technology, Xi’an 710021, China
| | - Zhe Guang
- School of Physics, Georgia Institute of Technology, 837 State Street NW, Atlanta, GA 30332, USA
| | - Ting Miao
- Department of Physics, School of Arts & Sciences, Shaanxi University of Science & Technology, Xi’an 710021, China
| | - Zohaib Ali
- School of Physics, Georgia Institute of Technology, 837 State Street NW, Atlanta, GA 30332, USA
- Nano-Optoelectronics Research Laboratory, Department of Physics, University of Agriculture Faisalabad, Faisalabad 38040, Pakistan
| | - Dun Qiao
- Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd CF37 1DL, UK
| | - Yiming Yao
- Department of Physics, School of Arts & Sciences, Shaanxi University of Science & Technology, Xi’an 710021, China
| | - Kexin Wu
- Department of Physics, School of Arts & Sciences, Shaanxi University of Science & Technology, Xi’an 710021, China
| | - Lei Zhou
- School of Electrical and Control Engineering, Shaanxi University of Science & Technology, Xi’an 710021, China
| | - Cheng Meng
- School of Electrical and Control Engineering, Shaanxi University of Science & Technology, Xi’an 710021, China
| | - Nigel Copner
- Faculty of Computing, Engineering and Science, University of South Wales, Pontypridd CF37 1DL, UK
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