Laser und Medizin Technology Berlin LMTB

Berlin, Germany

Laser und Medizin Technology Berlin LMTB

Berlin, Germany

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Reble C.,Laser und Medizin Technology Berlin LMTB | Reble C.,TU Berlin | Gersonde I.,Laser und Medizin Technology Berlin LMTB | Lieber C.A.,Childrens Hospital of Orange County | Helfmann J.,Laser und Medizin Technology Berlin LMTB
Biomedical Optics Express | Year: 2011

We present a Monte Carlo model, which we use to calculate the depth dependent sensitivity or sampling volume of different single fiber and multi-fiber Raman probes. A two-layer skin model is employed to investigate the dependency of the sampling volume on the absorption and reduced scattering coefficients in the near infrared wavelength range (NIR). The shape of the sampling volume is mainly determined by the scattering coefficient and the wavelength dependency of absorption and scattering has only a small effect on the sampling volume of a typical fingerprint spectrum. An increase in the sampling depth in nonmelanoma skin cancer, compared to normal skin, is obtained. © 2011 Optical Society of America.


Schleusener J.,Laser und Medizin Technology Berlin LMTB | Schleusener J.,Charité - Medical University of Berlin | Gluszczynska P.,Charité - Medical University of Berlin | Reble C.,Laser und Medizin Technology Berlin LMTB | And 8 more authors.
Experimental Dermatology | Year: 2015

Raman spectroscopy has proved its capability as an objective, non-invasive tool for the detection of various melanoma and non-melanoma skin cancers (NMSC) in a number of studies. Most publications are based on a Raman microspectroscopic ex vivo approach. In this in vivo clinical evaluation, we apply Raman spectroscopy using a fibre-coupled probe that allows access to a multitude of affected body sites. The probe design is optimized for epithelial sensitivity, whereby a large part of the detected signal originates from within the epidermal layer's depth down to the basal membrane where early stages of skin cancer develop. Data analysis was performed on measurements of 104 subjects scheduled for excision of lesions suspected of being malignant melanoma (MM) (n = 36), basal cell carcinoma (BCC) (n = 39) and squamous cell carcinoma (SCC) (n = 29). NMSC were discriminated from normal skin with a balanced accuracy of 73% (BCC) and 85% (SCC) using partial least squares discriminant analysis (PLS-DA). Discriminating MM and pigmented nevi (PN) resulted in a balanced accuracy of 91%. These results lie within the range of comparable in vivo studies and the accuracies achieved by trained dermatologists using dermoscopy. Discrimination proved to be unsuccessful between cancerous lesions and suspicious lesions that had been histopathologically verified as benign by dermoscopy. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.


Schleusener J.,Laser und Medizin Technology Berlin LMTB | Schleusener J.,Charité - Medical University of Berlin | Reble C.,Laser und Medizin Technology Berlin LMTB | Reble C.,TU Berlin | And 7 more authors.
Measurement Science and Technology | Year: 2014

Two different designs for fibre-coupled Raman probes are presented that are optimized for discriminating cancerous and normal skin by achieving high epithelial sensitivity to detect a major component of the Raman signal from the depth range of the epithelium. This is achieved by optimizing Raman spot diameters to the range of ≈200 m, which distinguishes this approach from the common applications of either Raman microspectroscopy (1-5 m) or measurements on larger sampling volume using spot sizes of a few mm. Video imaging with a depicted area in the order of a few cm, to allow comparing Raman measurements to the location of the histo-pathologic findings, is integrated in both designs. This is important due to the inhomogeneity of cancerous lesions. Video image acquisition is achieved using white light LED illumination, which avoids ambient light artefacts. The design requirements focus either on a compact light-weight configuration, for pen-like handling, or on a video-visible measurement spot to enable increased positioning accuracy. Both probes are evaluated with regard to spot size, Rayleigh suppression, background fluorescence, depth sensitivity, clinical handling and ambient light suppression. Ex vivo measurements on porcine ear skin correlates well with findings of other groups. © 2014 IOP Publishing Ltd.


Schleusener J.,Laser und Medizin Technology Berlin LMTB | Schleusener J.,Charité - Medical University of Berlin | Gluszczynska P.,Charité - Medical University of Berlin | Reble C.,Laser und Medizin Technology Berlin LMTB | And 6 more authors.
Applied Spectroscopy | Year: 2015

The application of fiber-coupled Raman probes for the discrimination of cancerous and normal skin has the advantage of a noninvasive in vivo application, easy clinical handling, and access to the majority of body sites, which would otherwise be limited by stationary Raman microscopes. Nevertheless, including optical fibers and miniaturizing optical components, as well as measuring in vivo, involves the sensibility to external perturbation factors that could introduce artifacts to the acquired Raman spectra and thereby potentially reduce classification performance. In this study, typical perturbation factors of Raman measurements with a Raman fiber probe, optimized for clinical in vivo discrimination of skin cancer, were investigated experimentally. Measurements were performed under standardized conditions in clinical settings in vivo on human skin, as well as ex vivo on porcine ears. Raman spectra were analyzed in the fingerprint region between 1150 and 1730 cm-1 using principal component analysis. The largest artifacts in the Raman spectra were found in measurements performed under the influence of strong ambient light conditions as well as after miscellaneous pre-treatments to the skin, such as use of a permanent marker or a sunscreen. Minor influences were also found in measurements using H2O immersion and when varying the probe contact force. The effect of reasonable variation of the fiber-bending radius was found to be of negligible impact. The influence of measurements on hairy or sun-exposed body sites, as well as inter-subject variation, was also investigated. The presented results may serve as a guide to avoid negative effects during the process of data acquisition and so avoid misclassification in tumor discrimination. © 2015 Society for Applied Spectroscopy


PubMed | Charité - Medical University of Berlin and Laser und Medizin Technology Berlin LMTB
Type: Journal Article | Journal: Experimental dermatology | Year: 2015

Raman spectroscopy has proved its capability as an objective, non-invasive tool for the detection of various melanoma and non-melanoma skin cancers (NMSC) in a number of studies. Most publications are based on a Raman microspectroscopic exvivo approach. In this invivo clinical evaluation, we apply Raman spectroscopy using a fibre-coupled probe that allows access to a multitude of affected body sites. The probe design is optimized for epithelial sensitivity, whereby a large part of the detected signal originates from within the epidermal layers depth down to the basal membrane where early stages of skin cancer develop. Data analysis was performed on measurements of 104 subjects scheduled for excision of lesions suspected of being malignant melanoma (MM) (n=36), basal cell carcinoma (BCC) (n=39) and squamous cell carcinoma (SCC) (n=29). NMSC were discriminated from normal skin with a balanced accuracy of 73% (BCC) and 85% (SCC) using partial least squares discriminant analysis (PLS-DA). Discriminating MM and pigmented nevi (PN) resulted in a balanced accuracy of 91%. These results lie within the range of comparable invivo studies and the accuracies achieved by trained dermatologists using dermoscopy. Discrimination proved to be unsuccessful between cancerous lesions and suspicious lesions that had been histopathologically verified as benign by dermoscopy.


Reble C.,TU Berlin | Gersonde I.,Laser und Medizin Technology Berlin LMTB | Andree S.,TU Berlin | Eichler H.J.,TU Berlin | Helfmann J.,Laser und Medizin Technology Berlin LMTB
Journal of Biomedical Optics | Year: 2010

Intrinsic Raman spectra of biological tissue are distorted by the influences of tissue absorption and scattering, which significantly challenge signal quantification. A combined Raman and spatially resolved reflectance setup is introduced to measure the absorption coefficient μ a and the reduced scattering coefficient μ' s of the tissue, together with the Raman signals. The influence of μ a and μ' s on the resonance Raman signal of β-carotene is measured at 1524 cm -1 by tissue phantom measurements and Monte Carlo simulations for μ a=0.01 to 10 mm -1 and μ' s=0.1 to 10 mm -1. Both methods show that the Raman signal drops roughly proportional to 1/μ a for μ a>0.2 mm -1 in the measurement geometry and that the influence of μ' s is weaker, but not negligible. Possible correction functions dependent on the elastic diffuse reflectance are investigated to correct the Raman signal for the influence of μ a and μ' s, provided that μ a and μ' s are measured as well. A correction function based on the Monte Carlo simulation of Raman signals is suggested as an alternative. Both approaches strongly reduce the turbidity-induced variation of the Raman signals and allow absolute Raman scattering coefficients to be determined. © 2010 Society of Photo-Optical Instrumentation Engineers.


Schmitt F.-J.,TU Berlin | Sudmeyer H.,Laser und Medizin Technology Berlin LMTB | Borner J.,TU Berlin | Lober J.,TU Berlin | And 6 more authors.
Optics and Lasers in Engineering | Year: 2011

Thin films of bacteria, proteins and other biochemical substances are almost always found on surfaces exposed to the environment. Optical methods enable innovative tools for the study of such films. Residua of proteins exhibit fluorescence when excited in the UV. We present a specially designed handheld measuring device that can detect organic contamination levels down to 100 ng/cm with measurement times shorter than a second. Using time-correlated spectroscopy methods the fluorescence detection of contamination levels on surfaces is possible even if the fluorescence spectra of contamination and base material overlap. The results presented in this paper show that a detection of contamination levels of bovine serum albumine (BSA) down to 100 ng/cm is possible on non-fluorescent materials. A theoretical analysis shows the possibility to detect BSA levels down to less than 1 ng/cm with the presented setup. Future development of handheld optical devices suitable for the detection or analysis of various compounds can be based on these results. A compact formalism is suggested that can be used to calculate the minimal concentration of a given organic contamination that can be detected with a certain measurement setup. © 2011 Elsevier Ltd.


Netz U.J.,Laser und Medizin Technology Berlin LMTB | Gersonde I.,Laser und Medizin Technology Berlin LMTB | Toelsner J.,Laser und Medizin Technology Berlin LMTB | Illing G.,Laser und Medizin Technology Berlin LMTB
Progress in Biomedical Optics and Imaging - Proceedings of SPIE | Year: 2011

In this paper we present two-dimensional phantom measurements of fluorescence light distribution in the frequency domain and reconstruction of three-dimensional fluorophore distribution. An experimental set-up was built up with two dimensional laser scanning, intensity modulation with frequencies up to 1 GHz, and two-dimensional imaging of modulated fluorescence light. Stable phantoms were developed simulating mammary tissue to perform measurements in a backscattering geometry for a variety of cylindrical fluorescence sources with different diameters, fluorophore concentrations, and surface distances at different modulation frequencies. At first calculated fluorescence light distributions from Monte-Carlo simulations was compared to measured data. In a second step from tomographic data sets of calculated fluorescent light, three-dimensional tomographic reconstructions of fluorophore distribution were performed. Finally three-dimensional tomographic reconstructions of fluorophore distribution were performed from tomographic fluorescence measurements. We found good concurrence between measured and calculated fluorescence distribution. Synthetic and real tomographic reconstruction showed good localization but underestimated the depth of fluorophore distribution. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

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