The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Michele Follen - One of the best experts on this subject based on the ideXlab platform.
-
Diffuse Reflectance patterns in cervical spectroscopy.
Gynecologic oncology, 2005Co-Authors: Nena M. Marin, Andrea Milbourne, Helen Rhodes, Thomas Ehlen, Dianne Miller, Lou Benedet, Rebecca Richards-kortum, Michele FollenAbstract:Our laboratory seeks to develop minimally invasive cost-effective methods to improve screening and detection of curable precursors to cervical cancer. Previously, we have presented pilot studies that assess the diagnostic power of auto-fluorescence and Diffuse Reflectance spectroscopy. In the present study, we evaluate Diffuse Reflectance spectra from a comprehensive 850 patient clinical trial to determine its ability to discriminate normal tissue from several grades of abnormal cervical tissue. Diffuse Reflectance spectra at four source detector separations measured from 549 cervical sites were available for analysis. Three classifiers were implemented: one used spectral data directly as input, a second used simple spectral features such as peak position and intensity, and one used principal component analysis for feature selection. Algorithms were developed and evaluated using leave-one-out cross-validation to classify normal and precancerous cervical tissue. The percentage of samples correctly classified was used to evaluate and compare the performance of the algorithms, as compared to histology. Diffuse Reflectance spectra of cervical precancer showed consistent differences from that of normal tissue at all source detector separations; Reflectance intensity of precancer was lower than that of normal tissue on average. Normal cervical tissue spectra show more intensity variation between patients than other tissue grades. Reflectance spectra acquired from the closest source detector separations consistently demonstrated the most relevant information for tissue classification. Two persistent spectral patterns demonstrated that the contribution of hemoglobin absorption and the wavelength-dependent spectral slope contained relevant information for classification. Spectral patterns in Diffuse Reflectance spectra can be used for the discrimination of normal cervical tissue from low grade and high grade squamous intraepithelial lesions.
-
Diffuse Reflectance patterns in cervical spectroscopy.
Gynecologic Oncology, 2005Co-Authors: Nena M. Marin, Andrea Milbourne, Helen Rhodes, Thomas Ehlen, Dianne Miller, Lou Benedet, Rebecca Richards-kortum, Michele FollenAbstract:Objectives. Our laboratory seeks to develop minimally invasive cost-effective methods to improve screening and detection of curable precursors to cervical cancer. Previously, we have presented pilot studies that assess the diagnostic power of auto-fluorescence and Diffuse Reflectance spectroscopy. In the present study, we evaluate Diffuse Reflectance spectra from a comprehensive 850 patient clinical trial to determine its ability to discriminate normal tissue from several grades of abnormal cervical tissue. Methods. Diffuse Reflectance spectra at four source detector separations measured from 549 cervical sites were available for analysis. Three classifiers were implemented: one used spectral data directly as input, a second used simple spectral features such as peak position and intensity, and one used principal component analysis for feature selection. Algorithms were developed and evaluated using leave-one-out cross-validation to classify normal and precancerous cervical tissue. The percentage of samples correctly classified was used to evaluate and compare the performance of the algorithms, as compared to histology. Results. Diffuse Reflectance spectra of cervical precancer showed consistent differences from that of normal tissue at all source detector separations; Reflectance intensity of precancer was lower than that of normal tissue on average. Normal cervical tissue spectra show more intensity variation between patients than other tissue grades. Reflectance spectra acquired from the closest source detector separations consistently demonstrated the most relevant information for tissue classification. Two persistent spectral patterns demonstrated that the contribution of hemoglobin absorption and the wavelength-dependent spectral slope contained relevant information for classification. Conclusions. Spectral patterns in Diffuse Reflectance spectra can be used for the discrimination of normal cervical tissue from low grade and high grade squamous intraepithelial lesions.
Hubert Van Den Bergh - One of the best experts on this subject based on the ideXlab platform.
-
Quantitative Diffuse Reflectance and transmittance spectroscopy of loosely packed powders
Spectrochimica Acta Part A: Molecular Spectroscopy, 1991Co-Authors: Andreas Mandelis, Farnaz Boroumand, Hubert Van Den BerghAbstract:A self-consistent discontinuum theory describing the dependence of the Diffuse Reflectance and Diffuse transmittance of powders on their optical absorption coeff. is presented. The theory is valid for particle sizes large compared to the exciting wavelength. It constitutes generalization and evolution of the statistical theory of abs. Diffuse Reflectance of powders put forth by N. T. Melamed (1963). Exptl. evidence of the spectroscopic use of the theory in detg. abs. optical absorption coeffs. self-consistently from both the Reflectance and transmittance measurement channels sequentially is provided for 2 powders, and the new photothermal technique of Diffuse Transmittance IR Fourier Transform Spectroscopy (DTIFTS) is introduced. The transmittance channel can be used advantageously to measure small changes in optical absorption spectra, as it is more sensitive to such changes than the Diffuse Reflectance. Practical exptl. limits of the validity of the discontinuum theory are also established.
Nena M. Marin - One of the best experts on this subject based on the ideXlab platform.
-
Diffuse Reflectance patterns in cervical spectroscopy.
Gynecologic oncology, 2005Co-Authors: Nena M. Marin, Andrea Milbourne, Helen Rhodes, Thomas Ehlen, Dianne Miller, Lou Benedet, Rebecca Richards-kortum, Michele FollenAbstract:Our laboratory seeks to develop minimally invasive cost-effective methods to improve screening and detection of curable precursors to cervical cancer. Previously, we have presented pilot studies that assess the diagnostic power of auto-fluorescence and Diffuse Reflectance spectroscopy. In the present study, we evaluate Diffuse Reflectance spectra from a comprehensive 850 patient clinical trial to determine its ability to discriminate normal tissue from several grades of abnormal cervical tissue. Diffuse Reflectance spectra at four source detector separations measured from 549 cervical sites were available for analysis. Three classifiers were implemented: one used spectral data directly as input, a second used simple spectral features such as peak position and intensity, and one used principal component analysis for feature selection. Algorithms were developed and evaluated using leave-one-out cross-validation to classify normal and precancerous cervical tissue. The percentage of samples correctly classified was used to evaluate and compare the performance of the algorithms, as compared to histology. Diffuse Reflectance spectra of cervical precancer showed consistent differences from that of normal tissue at all source detector separations; Reflectance intensity of precancer was lower than that of normal tissue on average. Normal cervical tissue spectra show more intensity variation between patients than other tissue grades. Reflectance spectra acquired from the closest source detector separations consistently demonstrated the most relevant information for tissue classification. Two persistent spectral patterns demonstrated that the contribution of hemoglobin absorption and the wavelength-dependent spectral slope contained relevant information for classification. Spectral patterns in Diffuse Reflectance spectra can be used for the discrimination of normal cervical tissue from low grade and high grade squamous intraepithelial lesions.
-
Diffuse Reflectance patterns in cervical spectroscopy.
Gynecologic Oncology, 2005Co-Authors: Nena M. Marin, Andrea Milbourne, Helen Rhodes, Thomas Ehlen, Dianne Miller, Lou Benedet, Rebecca Richards-kortum, Michele FollenAbstract:Objectives. Our laboratory seeks to develop minimally invasive cost-effective methods to improve screening and detection of curable precursors to cervical cancer. Previously, we have presented pilot studies that assess the diagnostic power of auto-fluorescence and Diffuse Reflectance spectroscopy. In the present study, we evaluate Diffuse Reflectance spectra from a comprehensive 850 patient clinical trial to determine its ability to discriminate normal tissue from several grades of abnormal cervical tissue. Methods. Diffuse Reflectance spectra at four source detector separations measured from 549 cervical sites were available for analysis. Three classifiers were implemented: one used spectral data directly as input, a second used simple spectral features such as peak position and intensity, and one used principal component analysis for feature selection. Algorithms were developed and evaluated using leave-one-out cross-validation to classify normal and precancerous cervical tissue. The percentage of samples correctly classified was used to evaluate and compare the performance of the algorithms, as compared to histology. Results. Diffuse Reflectance spectra of cervical precancer showed consistent differences from that of normal tissue at all source detector separations; Reflectance intensity of precancer was lower than that of normal tissue on average. Normal cervical tissue spectra show more intensity variation between patients than other tissue grades. Reflectance spectra acquired from the closest source detector separations consistently demonstrated the most relevant information for tissue classification. Two persistent spectral patterns demonstrated that the contribution of hemoglobin absorption and the wavelength-dependent spectral slope contained relevant information for classification. Conclusions. Spectral patterns in Diffuse Reflectance spectra can be used for the discrimination of normal cervical tissue from low grade and high grade squamous intraepithelial lesions.
Xiaoxia Zhang - One of the best experts on this subject based on the ideXlab platform.
-
Quantitative analysis of binary polymorphs mixtures of fusidic acid by Diffuse Reflectance FTIR spectroscopy, Diffuse Reflectance FT-NIR spectroscopy, Raman spectroscopy and multivariate calibration.
Journal of pharmaceutical and biomedical analysis, 2017Co-Authors: Canyong Guo, Xuefang Luo, Xiaohua Zhou, Beijia Shi, Juanjuan Wang, Jinqi Zhao, Xiaoxia ZhangAbstract:Vibrational spectroscopic techniques such as infrared, near-infrared and Raman spectroscopy have become popular in detecting and quantifying polymorphism of pharmaceutics since they are fast and non-destructive. This study assessed the ability of three vibrational spectroscopy combined with multivariate analysis to quantify a low-content undesired polymorph within a binary polymorphic mixture. Partial least squares (PLS) regression and support vector machine (SVM) regression were employed to build quantitative models. Fusidic acid, a steroidal antibiotic, was used as the model compound. It was found that PLS regression performed slightly better than SVM regression in all the three spectroscopic techniques. Root mean square errors of prediction (RMSEP) were ranging from 0.48% to 1.17% for Diffuse Reflectance FTIR spectroscopy and 1.60-1.93% for Diffuse Reflectance FT-NIR spectroscopy and 1.62-2.31% for Raman spectroscopy. The results indicate that Diffuse Reflectance FTIR spectroscopy offers significant advantages in providing accurate measurement of polymorphic content in the fusidic acid binary mixtures, while Raman spectroscopy is the least accurate technique for quantitative analysis of polymorphs.
A.j Deadman - One of the best experts on this subject based on the ideXlab platform.
-
NPL scales for radiance factor and total Diffuse Reflectance.
Metrologia, 2003Co-Authors: Christopher J. Chunnilall, A.j Deadman, L Crane, E UsadiAbstract:The National Reference Reflectometer has been developed by the National Physical Laboratory (NPL) to realize scales for radiance factor and total Diffuse Reflectance, the latter scale being obtained through the spatial integration of goniometric measurements of Reflectance. Analysis of its performance in the spectral region from 400 nm to 1000 nm shows that for spectrally neutral white materials such as matte white tiles and SpectralonTM plaques the instrument is capable of realizing 0/45 radiance factor measurements with an uncertainty of 0.2% (k = 2) and 0/d total Diffuse Reflectance measurements with an uncertainty of approximately 0.25% (k = 2). The uncertainties depend on the variation of Reflectance with angle, and there will therefore be some dependence on the material being measured. This instrument is now used to establish UK Diffuse Reflectance scales in the visible part of the spectrum.
-
Intercomparison of industrial near-infrared Diffuse Reflectance measurements
Analytica Chimica Acta, 1999Co-Authors: A.j Deadman, Paula C KneeAbstract:An intercomparison of Diffuse Reflectance measurements in the near-infrared region was carried out. Fourteen participants from industry and academia measured a number of different Reflectance standards, calibrated at the NPL, over the wavelength range from 800 to 2500 nm. Measurements were made in the integrating sphere geometries, i.e. specular included and specular excluded and in the 0/45 geometry. The results of the intercomparison are presented. The raw data results showed significant variations in the value of Diffuse Reflectance measured across industry, in excess of 80% difference from NPL Reflectance values in some cases. Renormalisation of the data to the NPL near-infrared Diffuse Reflectance scale significantly improved the agreement in measured values between participants, most being within 5% of the NPL values. Integrating sphere errors were present in many of the instruments used.