A rened analytical model for reconstruction problems in diuse reectance spectroscopy

A rened analytical model of spatially resolved diffuse reectance with small source-detector separations(SDSs)for the in vivo skin studies is proposed.Compared to the conventional model developed by Farrell et al.,it accounts for the limited acceptance angle of the detectorber.The rened model is validated in the wide range of optical parameters by Monte Carlo simulations of skin diffuse reectance at SDSs of units of mm.Cases of uniform dermis and two-layered epidermis-dermis structures are studied.Higher accuracy of the rened model compared to the conventional one is demonstrated in the separate,constraint-free reconstruction of absorption and reduced scattering spectra of uniform dermis from the Monte Carlo simulated data.In the case of epidermis-dermis geometry,the recovered values of reduced scattering in dermis are overestimated and the recovered values of absorption are underestimated for both analytical models.Presumably,in the presence of a thin mismatched topical layer,only the effective attenuation coe±cient of the bottom layer can be accurately recovered using a diffusion theorybased analytical model while separate reconstruction of absorption and reduced scattering fails due to the inapplicability of the method of images.These-ndings require implementation of more sophisticated models of light transfer in inhomogeneous media in the recovery algorithms.

Studies on the Effects of Deltamethrin on Sodium Net Transport Through the in vivo Amphibian Skin

The action of micromolar concentrations of Deltamethrin on sodium net transport through the in vivo skin of the South American toad Bufo arenarum was studied. The effect of pure ethanolic insecticide solutions and commercial formulations when applied on the mucosal surface was assayed. Deltamethrin provoked a concentration-independent inhibition; the highest inhibition was found at the lowest concentrations. At highest concentrations of the insecticide the J Na was not altered

RAMAN SPECTROSCOPY FOR IN VIVO TISSUE ANALYSIS AND DIAGNOSIS,FROM INSTRUMENT DEVELOPMENT TO CLINICAL APPLICATIONS

Raman spectroscopy is a noninvasive,nondestructive analytical method capable of determining the biochemical constituents based on molecular vibrations.It does not require sample preparation or pretreatment.However,the use of Raman spectroscopy for in vivo clinical applications will depend on the feasibility of measuring Raman spectra in a relatively short time period(a few seconds).In this work,a fast dispersive-type nearinfrared(NIR)Raman spectroscopy system and a skin Raman probe were developed to facilitate real-time,noninvasive,in vivo human skin measurements.Spectrograph image aberration was corrected by a parabolic-line fiber array,permitting complete CCD vertical binning,thereby yielding a 16-fold improvement in signal-to-noise ratio.Good quality in vivo skin NIR Raman spectra free of interference from fiber fluorescence and silica Raman scattering can be acquired within one second,which greatly facilitates practical noninvasive tissue characterization and clinical diagnosis.Currently,we are conducting a large clinical study of various skin diseases in order to develop Raman spectroscopy into a useful tool for non-invasive skin cancer detection.Intermediate data analysis results are presented.Recently,we have also successfully developed a technically more challenging endoscopic Laser-Raman probe for early lung cancer detection.Preliminary in vivo results from endoscopic lung Raman measurements are discussed.

POTENTIAL OF IN VIVO LATENT-TIME ESTIMATION BY LASER AND OPTICAL TECHNIQUES IN CLINICAL AND EXPERIMENTAL DERMATOLOGY

The lag(latency)time(LT)is known in dermatology clinic as an asymptomatic period till the development of skin eruptions.In the laboratory,the LT might determine the interval from"zero"point until the peak(s)of changes in measured laboratory parameter during the performed test.This paper discusses methodological and technical aspects of precise measurement of the LT in the living healthy and pathological skin by laser and optical technologies through clinical and experimental applications in dermatology.Based on a dynamics approach to measure,calculate and interpret the LT in blood and in interstitialfluid compartments of the skin tissue,this method has a potential to promote deeper understanding of the role of complex dynamic processes in the skin at a level of a molecule,and/or an organ in a whole organism.The method of the LT measurement in vivo also promotes new understanding of(patho)physiological,diagnostic and pharmacological aspects of certain dynamic skin lesions and dynamic complex processes that happen in the skin.Utilized laser and optical techniques showed high reliability and objectivity in collecting data from rapidly changed skin lesions and processes,demonstrating the LT measurement as a very easy-to-use calculation procedure with high informativity,which is extremely important for the clinical and laboratory environment.