| 1. |
- Wilson, Robert H., et al.
(författare)
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Quantitative short-wave infrared multispectral imaging of in vivo tissue optical properties
- 2014
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Ingår i: Journal of Biomedical Optics. - : SPIE-Intl Soc Optical Eng. - 1083-3668 .- 1560-2281. ; 19:8
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Tidskriftsartikel (refereegranskat)abstract
- Extending the wavelength range of spatial frequency domain imaging (SFDI) into the short-wave infrared (SWIR) has the potential to provide enhanced sensitivity to chromophores such as water and lipids that have prominent absorption features in the SWIR region. Here, we present, for the first time, a method combining SFDI with unstructured (zero spatial frequency) illumination to extract tissue absorption and scattering properties over a wavelength range (850 to 1800 nm) largely unexplored by previous tissue optics techniques. To obtain images over this wavelength range, we employ a SWIR camera in conjunction with an SFDI system. We use SFDI to obtain
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| 2. |
- Pham, T. H, et al.
(författare)
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Quantifying the absorption and reduced scattering coefficients of tissuelike turbid media over a broad spectral range with noncontact Fourier-transform hyperspectral imaging
- 2000
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Ingår i: Applied Optics. - 2155-3165. ; 39:34, s. 6487-6497
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Tidskriftsartikel (refereegranskat)abstract
- Absorption (mu (a)) and reduced scattering (mu (s)') spectra of turbid media were quanti fied with a noncontact imaging approach based on a Fourier-transform interferometric imaging system (FTIIS). The FTIIS was used to collect hyperspectral images of the steady-state diffuse reflectance from turbid media. Spatially resolved reflectance data from Monte Carlo simulations were fitted to the recorded hyperspectral images to quantify mu (a) and mu (s)' spectra in the 550-850-nm region. A simple and effective calibration approach was introduced to account for the instrument response. With reflectance data that were close to and far from the source (0.5-6.5 mm), mu (a) and mu (')(s) of homogeneous, semi-infinite turbid phantoms with optical property ranges comparable with those of tissues were determined with an accuracy of +/-7% and +/-3%, respectively. Prediction accuracy for mu (a) and mu (s)' degraded to +/-12% and +/-4%, respectively, when only reflectance data close to the source (0.5-2.5 mm) were used. Results indicate that reflectance data close to and far hom the source are necessary for optimal quantification of mu (a) and mu (s)'. The spectral properties of mu (a) and mu (s)' values were used to determine the concentrations of absorbers and scatterers, respectively. Absorber and scatterer concentrations of two-chromophore turbid media were determined with an accuracy of +/-5% and +/-3%, respectively. (C) 2000 Optical Society of America OCIS codes: 170.0110, 170.7050, 170.6510, 070.2590, 120.3180.
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| 3. |
- Rohrbach, Daniel J., et al.
(författare)
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Characterization of nonmelanoma skin cancer for light therapy using spatial frequency domain imaging
- 2015
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Ingår i: Biomedical Optics Express. - : Optical Society of America. - 2156-7085. ; 6:5, s. 1761-1766
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Tidskriftsartikel (refereegranskat)abstract
- The dosimetry of light-based therapies critically depends on both optical and vascular parameters. We utilized spatial frequency domain imaging to quantify optical and vascular parameters, as well as estimated light penetration depth from 17 nonmelanoma skin cancer patients. Our data indicates that there exist substantial spatial variations in these parameters. Characterization of these parameters may inform understanding and optimization of the clinical response of light-based therapies.
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| 4. |
- Saager, Rolf B., 1974-, et al.
(författare)
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From theory to practice : the broadening role of polydimethylsiloxane phantoms as an intermediary between model validation and instrument performance testing (Conference Presentation)
- 2016
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Ingår i: Proceedings Volume 9700, Design and Quality for Biomedical Technologies IX; 97000G (2016). - : SPIE - International Society for Optical Engineering.
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Konferensbidrag (refereegranskat)abstract
- Polydimethylsiloxane (PDMS) has been a popular medium to fabricate tissue simulating optical phantoms. Recently, its use has significantly expanded in instrument calibration and performance testing, validation of advanced models of light transport of complex tissue geometries and evaluation of novel measurement modalities. To meet these demands, fabrication methods of these optical phantoms have become more refined and its structure and constituent components (i.e. dyes and scattering agents) have evolved to better mimic optical properties of tissue spanning both visible and near infrared regimes. We present efforts at the Beckman Laser Institute that address these challenges through PDMS phantoms.
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| 5. |
- Saager, Rolf B., 1974-, et al.
(författare)
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In vivo measurements of cutaneous melanin across spatial scales : using multiphoton microscopy and spatial frequency domain spectroscopy
- 2015
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Ingår i: Journal of Biomedical Optics. - : SPIE - International Society for Optical Engineering. - 1083-3668 .- 1560-2281. ; 20:6
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Tidskriftsartikel (refereegranskat)abstract
- The combined use of nonlinear optical microscopy and broadband reflectance techniques to assess melanin concentration and distribution thickness in vivo over the full range of Fitzpatrick skin types is presented. Twelve patients were measured using multiphoton microscopy (MPM) and spatial frequency domain spectroscopy (SFDS) on both dorsal forearm and volar arm, which are generally sun-exposed and non-sun-exposed areas, respectively. Both MPM and SFDS measured melanin volume fractions between ∼5% (skin type I non-sun-exposed) and 20% (skin type VI sun exposed). MPM measured epidermal (anatomical) thickness values ∼30–65 μm, while SFDS measured melanin distribution thickness based on diffuse optical path length. There was a strong correlation between melanin concentration and melanin distribution (epidermal) thickness measurements obtained using the two techniques. While SFDS does not have the ability to match the spatial resolution of MPM, this study demonstrates that melanin content as quantified using SFDS is linearly correlated with epidermal melanin as measured using MPM (R2=0.8895). SFDS melanin distribution thickness is correlated to MPM values (R2=0.8131). These techniques can be used individually and/or in combination to advance our understanding and guide therapies for pigmentation-related conditions as well as light-based treatments across a full range of skin types.
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| 6. |
- Torabzadeh, Mohammad, et al.
(författare)
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hyperspectral characterization of tissue simulating phantoms using a supercontinuum laser in a spatial frequency domain imaging instrument
- 2018
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Ingår i: Proceedings Volume 10486, Design and Quality for Biomedical Technologies XI; 104860G (2018). - : SPIE - International Society for Optical Engineering.
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Konferensbidrag (refereegranskat)abstract
- Hyperspectral Imaging (HSI) is a growing field in tissue optics due to its ability to collect continuous spectral features of a sample without a contact probe. Spatial Frequency Domain Imaging (SFDI) is a non-contact wide-field spectral imaging technique that is used to quantitatively characterize tissue structure and chromophore concentration. In this study, we designed a Hyperspectral SFDI (H-SFDI) instrument which integrated a supercontinuum laser source to a wavelength tuning optical configuration and a sCMOS camera to extract spatial (Field of View: 2cm×2cm) and broadband spectral features (580nm-950nm). A preliminary experiment was also performed to integrate the hyperspectral projection unit to a compressed single pixel camera and Light Labeling (LiLa) technique.
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| 7. |
- Pham, T. H, et al.
(författare)
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Quantifying the optical properties and chromophore concentrations of turbid media by chemometric analysis of hyperspectral diffuse reflectance data collected using a fourier interferometric imaging system
- 2001
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 1943-3530 .- 0003-7028. ; 55:8, s. 1035-1045
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Tidskriftsartikel (refereegranskat)abstract
- A non-contact Fourier transform interferometric imaging system was used to collect hyperspectral images of the steady-state diffuse reflectance from a point source in turbid media for the spectral range of 550-850 nm. Steady-state diffuse reflectance profiles were generated from the hyperspectral images, and partial least-squares (PLS) regression was performed on the diffuse reflectance profiles to quantify absorption (mu (alpha)) and reduced scattering (mu (s)') properties of turbid media. The feasibility of using PLS regression to predict optical properties was examined for two different sets of spatially-resolved diffuse reflectance data. One set of data was collected from 40 turbid phantoms, while the second set was generated by convolving Monte Carlo simulations with the instrument response of the imaging system. Study results show that PLS prediction of mu (alpha) and mu (s)' was accurate to within +/-8% and +/-5%, respectively, when the model was trained on turbid phantom data. Moreover, PLS prediction of optical properties was considerably faster and more efficient than direct least-squares fitting of spatially-resolved profiles. When the PLS model was trained on Monte Carlo simulated data and subsequently used to predict mu (alpha) and mu (s)' from the diffuse reflectance of turbid phantom, the percent accuracies degraded to +/-12% and +/-5%, respectively. These accuracy values are applicable to homogenous, semi-infinite turbid phantoms with optical property ranges comparable to tissues.
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| 8. |
- Sunar, Ulas, et al.
(författare)
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Characterization of nonmelanoma skin cancer with multimodal imaging
- 2014
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Ingår i: Biomedical Optics 2014. - Washington, D.C. : OSA Publishing. - 9781557529978
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Konferensbidrag (refereegranskat)abstract
- To guide intervention planning of nonmelanoma skin cancer (NMSC), information about the tumor depth and thickness as well as functional contrast is desired. The results indicate that ultrasound and spatial frequency domain imaging can provide accurate structural and enhanced contrasts in NMSC.
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