Optical absorption and scattering properties of bulk porcine muscle phantoms from interstitial radiance measurements in 650–900 nm range (original) (raw)
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Spectroscopic measurements and characterization of soft tissue phantoms
Design and Performance Validation of Phantoms Used in Conjunction with Optical Measurement of Tissue V, 2013
Tissue phantoms are important tools to calibrate and validate light propagation effects, measurements and diagnostic test in real biological soft tissue. We produce low cost phantoms using standard commercial jelly, distillated water, glycerol and a 20% lipid emulsion (Oliclinomel N7-1000 ®) was used in place of the usual Intralipid®. In a previous work we designed a protocol to elaborate high purity phantoms which can be used over months. We produced three different types of phantoms regarding the lipid emulsion -glycerol -gelatin -water composition: Pure gelatin phantoms, lipid in glycerol, and lipid in gelatin phantoms were produced and different concentrations of the lipid emulsion were used to study optical propagation properties of diffusive mixtures. Besides, 1.09 µm poly latex spheres in distilled water were used to produce reference phantoms. In order to use all the phantom sides, the phantoms were produced in disposable spectrometer cuvettes, designed for fluorescence studies. Measurements were performed using an OceanOptics 4000 channels spectrophotometer and integrating spheres. For the scattering measurements a homemade goniometer with a high resolution angular scale was used and the scattering detector was a linear array of optical fibers, with an angular collimator, connected to the spectrophotometer. White LED was used as light source, and the 6328.8 nm HeNe Laser was used for calibration. In this work we present characterization measurements for gelatin and microspheres phantoms using spectral reflectance, diffuse and direct spectral transmittance, and angle scattering measurements. The results of these measurements and their comparison are presented. Downloaded From: http://spiedigitallibrary.org/ on 11/25/2013 Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 8583 85830D-2 Downloaded From: http://spiedigitallibrary.org/ on 11/25/2013 Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 8583 85830D-7 Downloaded From: http://spiedigitallibrary.org/ on 11/25/2013 Terms of Use: http://spiedl.org/terms
Instrumentation Science & Technology, 2004
Optical coefficients of phantoms were determined through measurement of backscattered light using an optical fiber device. These phantoms, composed of milk and laser dye, were selected, dimensioned, and characterized according to typical values of optical parameters found in the literature for biological tissues in the near-infrared (NIR) region. An optical fiber device was used to deliver light to the surface of the phantom at an angle of 458, as well as to collect light from 12 different locations. Using a combination of two theoretical models based on photon diffusion theory, optical parameters could be determined from experimental curves with an error of prediction lower than 20%. The novelty of the present work is in the combination of theoretical models that had previously been applied to different device architectures for the delivery and collection of light. Moreover, the low cost and reliable proposed phantom is shown to be adequate for the optical simulation of biological tissues.
Optical properties of biological tissues: a review
This corrigendum corrects a mistake in , showing anisotropy versus wavelength, in which the breast data from were misplotted and mislabelled. The corrected figure is given here as figure 8(a). (b) shows a close-up of the data from Peters et al (1990), presenting the wavelength dependence of the anisotropy of scattering for the five types of tissue in breast. (a) Figure 8. (a) Corrected version of figure 8, showing anisotropy of scattering versus wavelength. (b) Detail of data from Peters et al (1990), showing wavelength dependence of anisotropy of scattering for the five types of tissue in breast.
Optics Express, 2008
A novel, multi-wavelength, fiberoptic system was constructed, evaluated and implemented to determine internal tissue optical properties at ultraviolet A (UVA) and visible (VIS) wavelengths. Inverse modeling was performed with a neural network to estimate absorption and reduced scattering coefficients based on spatially-resolved reflectance distributions. The model was calibrated with simulated reflectance datasets generated using a condensed Monte Carlo approach with absorption coefficients up to 85 cm -1 and reduced scattering coefficients up to 118 cm -1 . After theoretical and experimental evaluations of the system, optical properties of porcine bladder, colon, esophagus, oral mucosa, and liver were measured at 325, 375, 405, 445 and 532 nm. These data provide evidence that as wavelengths decrease into the UVA, the dominant tissue chromophore shifts from hemoglobin to structural proteins such as collagen. This system provides a high level of accuracy over a wide range of optical properties, and should be particularly useful for in situ characterization of highly attenuating biological tissues in the UVA-VIS.
Optical properties and chromophore concentration measurements in tissue-like phantoms
Optics …, 2005
Biomedical laser light dosimetry relies on spatial light distribution measurements in combination with the appropriate laser-tissue interaction model that may be used to determine the tissue optical coefficients and the fluorophore concentration from its fluorescence spectra. Therefore, modelling of light transport in tissue, for optimization of laser dosimetry, requires the development of simple theoretical models and the experimental implementation in tissuesimulating phantoms, with known optical and fluorescence properties.
Physics in Medicine and Biology, 1999
A method is described for measuring optical properties and deriving chromophore concentrations from diffuse reflection measurements at the surface of a turbid medium. The method uses a diffusion approximation model for the diffuse reflectance, in combination with models for the absorption and scattering coefficients. An optical fibre-based set-up, capable of measuring nine spectra from 400 to 1050 nm simultaneously, is used to test the method experimentally. Results of the analyses of phantom and in vivo measurements are presented. These demonstrate that in the wavelength range from 600 to 900 nm, tissue scattering can be described as a simple power dependence of the wavelength and that the tissue absorption can be accurately described by the addition of water, oxy-and deoxyhaemoglobin absorption.
Lasers in surgery and …, 1994
This study examines the validity of optical property measurements by comparing surface temperatures rises predicted by a well-tested mathematical model with temperatures measured experimentally during laser irradiation. Analysis is based on the early temperature response that is proportional to the absorption coefficient. The results of the investigation suggest that values for tissue absorption coefficient can be greatly overestimated when current spectrophotometric techniques are used. This seems especially true when a broad light beam and a low portto-beam-size ratio are used for transmission and reflection measurements with an integrating sphere. o
Effect of dependent scattering on the optical properties of Intralipid tissue phantoms
Biomedical Optics Express, 2011
The calibration of optical tissue-simulating phantoms remains an open question in spite of the many techniques proposed for accurate measurements of optical properties. As a consequence, a reference phantom with well known optical properties is still missing. As a first step towards a reference phantom we have recently proposed to use dilutions of Intralipid 20%. In this paper we discuss a matter that is commonly ignored when dilutions are prepared, i.e., the possibility of deviations from the simple linear relationships between the optical properties of the dilution and the Intralipid concentration due to the effects of dependent scattering. The results of an experimental investigation showed that dependent scattering does not affect absorption. As for the reduced scattering coefficient the effect can be described adding a term proportional to the square of the concentration. However, for concentrations of interest for tissue optics deviations from linearity remain within about 2%. The experimental investigation also showed that the microphysical properties of Intralipid are not affected by dilution. These results show the possibility to easily obtain a liquid diffusive phantom whose optical properties are known with error smaller than about 1%. Due to the intrinsic limitations of the different techniques proposed for measuring the optical properties it seems difficult to obtain a similar accuracy for solid phantoms.
Optics and Spectroscopy, 2011
The purpose of the present study is to determine the optical properties of normal and thermally coagulated chicken liver at 720, 740, 770, 810, 825 and 840 nm wavelengths of laser irradiation. So, we were able to evaluate these optical properties (absorption and scattering coefficients) with ex-vivo study using Kubelka Munk Model (KMM) from the radial dependence of the diffuse reflectance with femtosecond pulsed laser in near IR region. These coefficients were significantly increased with coagulation. The penetration depths of the diffused light have been reported to a maximum value of 8.12 ± 0.36 mm in normal liver and 2.49 ± 0.17 mm in coagulated liver at 840 nm showing increasing behavior towards IR region. The Monte Carlo simulation was used to check the theoretical validation of measured optical properties of the tissue that showed a good match with our experimental results. We believe that these differences in optical properties will be helpful for the understanding arid optimal use of laser applications in medicine and differential diagnosis of tissues by using different optical methods. Especially for the investigation of biological tissue for photodynamic therapy (PDT), the knowledge of the specific optical properties and their thermo-induced changes is important.
Experimental and analytical comparative study of optical coefficient of fresh and frozen rat tissues
Journal of Biomedical Optics, 2013
Optical properties of fresh and frozen tissues of rat heart, kidney, brain, liver, and muscle were measured in the 450-to 700-nm range. The total reflectance and transmittance were measured using a well-calibrated integral sphere setup. Absorption coefficient μ a and reduced scattering coefficient μ 0 s were derived from the experimental measurements using the inverse adding doubling technique. The influence of cryogenic processing on optical properties was studied. Interindividual and intraindividual variations were assessed. These new data aim at filling the lack of validated optical properties in the visible range especially in the blue-green region of particular interest for fluorescence and optogenetics preclinical studies. Furthermore, we provide a unique comparison of the optical properties of different organs obtained using the same measurement setup for fresh and frozen tissues as well as an estimate of the intraindividual and interindividual variability. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.