Academic literature on the topic 'Biomedical photometer'

Biomedical photometersʼ information-measuring systems with ellipsoidal reflectors have acceptable results in determining of biological tissues optical properties in the visible and near-infrared spectral range. These photometers make it possible to study the optical radiation propagation in turbid media for direct and inverse problems of light-scattering optics. The purpose of this work is to study the influence of the ellipsoidal reflectors design parameters on the results of biomedical photometry when simulating the optical radiation propagation in a system of biological tissue and reflectors in transmitted and reflected light.The paper substantiates the choice of the ellipsoidal reflectors’ focal parameter for efficient registration of forward and backscattered light. The methodology of the process is illustrated by the results of a model experiment using the Monte Carlo simulation for samples of human brain white and gray matter at the visible range of 405 nm, 532 nm, and 650 nm. The total transmittance, diffuse reflectance, and absorption graphs depending on the sample thickness were obtained. Based on the introduced concepts of the ellipsoidal reflector efficiency index and its efficiency factor, the expediency of choosing the ellipsoidal reflectors focal parameter is analyzed to ensure the registration of the maximum amount of scattered light. The graphs of efficiency index in reflected and transmitted light for different thickness samples of white and gray matter and efficiency factors depending on the sample thickness were obtained.The influence of the reflectors ellipticity on the illuminance of various zones of photometric images using the example of an absorbing biological medium – pig liver tissue – at wavelength of 405 nm with a Monte Carlo simulation was analyzed.The optical properties of biological media (scattering and absorption coefficients, scattering anisotropy factor, refractive index) and the samples’ geometric dimensions, particularly the thickness, are predetermined when choosing the ellipsoidal reflectors parameters for registration of the scattered light. Coordinates of the output of photons and their statistical weight obtained in the Monte Carlo simulation of light propagation in biological tissue have a physical effect on a characteristic scattering spot formation in the receiving plane of a biomedical photometer with ellipsoidal reflectors.

The ability to register and analyze the spatial distribution of light scattered within the full solid angle is the basis for the development and improvement of information-measuring systems and software and hardware complexes for problems of optical biomedical diagnostics. The greatest contribution to light scattering at non-invasive methods of biomedical research are made by the layers of human skin, affecting the depth of probing and the resolution of diagnostic systems. The significant individual variability of the optical properties of biological tissues does not allow practically (clinically) assessing their effect on the light scattering characteristics; therefore, the use of methods for modeling the optical radiation propagation in media in the measuring tools functioning context makes it possible to provide such a prognostic analysis. The goal of this work is a comparative evaluation of the results of the light propagation in human skin layers by Monte Carlo simulation using information-measuring systems of a biomedical photometer with ellipsoidal reflectors and a goniophotometer. The Monte Carlo simulation results of light scattering in dermis and epidermis at a wavelength of 632.8 nm using spatial photometry methods and the "BT_Mod" software, as well as coordinates, direction, and statistical weight of photons, allows the ray-tracing in a biomedical photometer with ellipsoidal reflectors are presented in this work. As a result of modeling, graphs of the dependence of optical coefficients (transmission T, diffuse reflection Rd, and absorption A) for the studied tissues of various thicknesses on the value of the scattering anisotropy factor were obtained, as well as photometric images of the second focal plane of ellipsoidal reflectors when receiving a scattering spot in reflected and transmitted light. Diagrams of the averaged scattering indicatrix at three thicknesses of the epidermis and dermis were obtained for a set of biophysically significant values of the scattering anisotropy factor, based on which the integral distribution of the photons statistical weight in diffuse scattered light was analyzed. A quantitative assessment of the illuminance level of images is carried out according to the zone analysis principles in photometry by ellipsoidal reflectors. The resulting graphs of the illuminance dependence the external and middle rings of photometric images in reflected and transmitted light. The results of the research make it possible to analyze the spatial distribution of light scattered by the human skin layers (epidermis and dermis) within the full solid angle, which can be used in problems of optical dosimetry and medical imaging in diagnostic, endoscopic, and therapeutic methods of biophotonics.

The correct accounting of laser emitter parameters for improvement of diagnostic authenticity of methods of optical biomedical diagnostic is important problem for applied biophotonic tasks. The purpose of the current research is estimation of influence of energy distribution profile in transversal section of laser beam on light scattering by human skin layers at photometry by ellipsoidal reflectors.Biomedical photometer with ellipsoidal reflectors for investigation of biological tissue specimens in transmitted and reflected light uses laser probing radiation with infinitely thin, Gauss-type and uniform cross-section profile. Distribution of beams with denoted profiles, which consist of 20 million photons with wavelength 632.8 nm, was modeled by using of Monte-Carlo simulation in human skin layers (corneous layer, epidermis, derma and adipose tissue) of various anatomic thickness and with ellipsoidal reflectors with focal parameter equal to 16.875 mm and eccentricity of 0.66.The modeling results represent that illuminance distribution in zones of photometric imaging is significantly influenced by the laser beam cross-section profile for various thickness of corneous layer and epidermis in transmitted and reflected light, and also derma in reflected light. Illuminance distribution for adipose tissue in reflected and transmitted light, and also derma in transmitted light, practically do not depend of laser beam profile for anatomic thicknesses, which are appropriate for human skin on various sections of body.There are represented results of modified Monte-Carlo simulation method for biomedical photometer with ellipsoidal reflectors during biometry of human skin layers. For highly scattered corneous layer and epidermis the illumination of middle and external rings of photometric images changes depending from the laser beam profile for more than 50 % in transmitted and 30 % in reflected light. For weakly scattering skin layers (derma and adipose layer) the influence of profile can be observed only for derma in reflected layer and is equal not more than 15 %.

Receptor-mediated pigment aggregation within pigment cells (chromatophores) of an isolated fish scale is an ideal model system for functional receptor studies. The superficial layer of the scale contains both dermal chromatophores and postganglionic sympathetic nerves. By means of stimulation of the nerves, or by addition of appropriate receptor agonists, it is possible to elicit pigment aggregation within the chromatophores. A single fish can contribute hundreds of scales, various pharmacological and biochemical experiments are easily carried out and the physiological response, i.e. pigment aggregation, is readily evaluated by the aid of a light microscope or a simple scale photometer. A denervation model, based on isolated scales, permits studies of factors involved in the sensitivity change, which typically takes place after experimental or pathological denervation. By using isolated fish scales it is quite simple to illustrate many biomedically important concepts, like receptor theory and nerve-effector cell communication. This makes the scale a very useful preparation in biomedical education.

AbstractMagnetic core/shell (CS) nanocomposites (MNCs) are synthesized using a simple method, in which a magnesium ferrite nanoparticle (MgFe_2O_4) is a core, and an amorphous silicon dioxide (silica SiO_2) layer is a shell. The composition, morphology, and structure of synthesized particles are studied using X-ray diffraction, field emission electron microscopy, transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), scattering electrophoretic photometer, thermogravimetric analysis (TGA), and Mössbauer spectroscopy. It is found that the MgFe_2O_4/SiO_2 MNC has the core/shell structure formed by the Fe‒O–Si chemical bond. After coating with silica, the MgFe_2O_4/SiO_2 MNC saturation magnetization significantly decreases in comparison with MgFe_2O_4 particles without a SiO_2 shell. Spherical particles agglomerated from MgFe_2O_4 nanocrystallites ∼9.6 and ∼11.5 nm in size function as cores coated with SiO_2 shells ∼30 and ∼50 nm thick, respectively. The total size of obtained CS MNCs is ∼200 and 300 nm, respectively. Synthesized CS MgFe_2O_4/SiO_2 MNCs are very promising for biomedical applications, due to the biological compatibility of silicon dioxide, its sizes, and the fact that the Curie temperature is in the region required for hyperthermal therapy, 320 K.

Background: the blood electrolytes analysis is a routine laboratory test which proper execution would help in the diagnosis of hydro-electrolytes disorders. The objective of this work was to assess the internal quality control of the sodium and potassium tests from the pre-pre-analytical phase to the post-analytical phase. Material and Methods: This was a cross-sectional study which took in the laboratory of biochemistry at the Institute of Cardiology, Abidjan, Ivory Coast from March 1st to March 31, 2009. We used the flame photometer to measure the sodium and potassium electrolytes level in the internal control Exatrol-Normal from Biolabo®. Clinical samples were also taken for the determination of the same electrolytes levels. The pre-pre-analytical quality indicators depending on the physicians order, the pre-analytical quality, the analytical quality and the post-analytical indicators under the control of the laboratory were assessed by using “NF en ISO 15189 version 2007” check list: Particular requirements for quality and competence for biomedical laboratories paragraph 5.4.1, 5.4.2, 5.5 and 5.7. Data were captured into Microsoft Excel [Microsoft Corporation, Redmond, WA] and then imported and analyzed using QI Macros SPC Software for Excel®. The levels of Na+ and K+ in the control material Exatrol Normal from Biolabo® were represented as follow: mean (m), Standard deviation (SD). The values of the monthly distribution of Na+ and K+ concentrations around the mean were used to draw the Levey-Jennings diagram and Wesgard’s rules were used to evaluate the performances of the analytical process. Results: a total of 112 electrolytes analysis order were received at the biochemistry laboratory. For the pre-pre-analytical phase, the analysis of these requests forms revealed that 81 (72.3%) requests forms carried no clinical information. The non-compliance of the samples were mainly represented by the sampling under tight tourniquet 4 (3.6%), followed by the non-respect of the succession of tubes during multiple sampling process 3 (2.7%). For the analytical phase, the monthly Levey-Jennings diagram showed a dispersion of the two electrolytes Exatrol-Normal Biolabo® levels ​​between the mean plus or minus 2 standard deviations [m ± 2SD]: 139.34 ± 2.84 mmol/L for Na+ and for K+, between [m± SD]: 4.2 ± 0.78 mmol/L. The analytical performances assessment for the two Levey-Jennings diagrams by using Wesgard’s rules did not found any significant critical deviations with regard to the distribution of Na+ and K+ levels. For clinical samples, isolated hyponatremia was the most common disturbance (30.4%) followed by isolated hypokalemia (12.5%). At the post-analytical phase we observed for test execution a mean turnaround time of 34 ± 5.2 minutes with extremes ranging from 23 to 95 minutes. One case (0.9%) of transcription error was noted. Conclusion: the internal quality control process is applied in the clinical biochemistry laboratory at the Institute of Cardiology, Abidjan. A systematic verification system of the different phases of the analytical process helped to follow quality indicators at all levels of the pre, analytical and post analytical process and corrective actions were taken if necessary. Better collaboration between clinicians requesting electrolytes analysis and biologists performing the analysis is necessary to improve the pre-pre-analytical phase and, beyond that, improve the patient outcome throughout a comprehensive care.

У роботі вирішено комплекс задач, що дозволило вирішити важливу науково-прикладну проблему розробки методу побудови і застосування еліпсоїдальних рефлекторів в системах реєстрації та аналізу розсіяного оптичного випромінювання, а також апробації нових конструктивних, функціональних та медико-біологічних рішень. Це дало змогу теоретично та експериментально обґрунтувати метод і апаратні засоби застосування еліпсоїдальних рефлекторів для фотометрії світлорозсіяння біологічними середовищами при виявленні їх оптичних властивостей та ідентифікації фізичного та фізіологічного стану. Запропоновано фундаментальну основу вирішення вказаної проблеми завдяки вперше розробленого механізму рей-трейсингу, що взаємо пов’язує параметри джерела випромінювання, біологічного середовища, еліпсоїдального дзеркала та матричного приймача випромінювання в інформаційно-вимірювальній системі біомедичного фотометру з еліпсоїдальними рефлекторами, і який дозволяє вирішувати пряму та інверсну задачі поширення оптичного випромінювання методом статистичного моделювання Монте-Карло.
The thesis is devoted to the solution of the important scientifically applied problem of development the construction and application method of ellipsoidal reflectors in the registration and analysis systems of scattered optical radiation, as well as approbation of new structural, functional and biomedical solutions. This made it possible to theoretically and experimentally substantiate the method and hardware of the use the ellipsoidal reflectors for photometry of light scattering by biological media in the detection of their optical properties and identification of physical and physiological state. A fundamental basis for solving this problem is the first-time developed mechanism of ray-tracing, which colligate the parameters of the radiation source, biological media, ellipsoidal reflector and matrix photodetector in the information-measuring system of biomedical photometer, which allows to solve the direct and inverse problems of light propagation by the Monte Carlo statistical simulation. The main content of the thesis is outlined in eight chapters, which present and substantiate the goal and results of the work. The first chapter presents the results of analytical review and literary search, which reveal the tasks raised in the doctorate thesis. In particular, the methods of biophotonics that are most commonly used in the study of different biological media are given. The features of optical radiation propagation in biological media are analyzed, as well as the basic principles of the transfer radiative theory, which mathematically and analytically interpret this process. Typical photometric tools used for the study of biological media, boundary conditions of their use, and functional limitations are analyzed. The second chapter is devoted to the development a method of investigation the biological media optical properties. Structural schemes of basic photometers with ellipsoidal reflectors and features of their functioning are presented. The mathematical apparatus for calculating the ray tracing in a reflector with an internal ellipsoidal reflecting surface is presented, and the main types of ray trajectories are considered. The algorithm of the proposed mechanism of ray tracing and the features of its software are presented. The results of aberration analysis of ellipsoidal reflector are shown. The third chapter is devoted to the development of Monte Carlo models of light propagation in the information-measuring system of biomedical photometer with ellipsoidal reflectors. The features of the input data formation and the basic simulation algorithm are substantiated, as well as the boundary conditions of simulation. The analytical models of software adaptation of radiation source parameters, the receiving system, as well as the boundaries and scattering-absorption properties of the biological media that underlie the simulation are presented. The principles of determination the optical coefficients, algorithm and grounds of software implementation of Monte Carlo simulation in the system "radiation source + biological media + measuring tool" are presented. In the fourth chapter proposed the features of designing photometers with ellipsoidal reflectors by improving the standard equipment for microscopy, as well as in the construction of individual prototypes. Schemes of zone analysis at processing of photometric images obtained by photometry by ellipsoidal reflectors are considered. Mathematical and analytical aspects of solving the inverse problem of the radiative transfer theory by methods of Kubelka-Munk and inverse Monte-Carlo in the context the work of biomedical photometers with ellipsoidal reflectors operating in reflected and also in reflected and transmitted light are presented. The interrelation of photometric images and optical properties of the investigated biological media is considered. In the fifth chapter discusses the technological principles of ellipsoidal reflectors production and control. The materials choice of ellipsoid for different methods of shaping the aspherical surface is substantiated. The principles of production of metallic mirror ellipsoids of revolution using vertical-boring technology, as well as 3D printing technology from plastic are formulated. Practical aspects of applying a mirror coating to the inner ellipsoidal surface from plastic are determined. The analytical model and technical stages the shape control of the ellipsoidal surface are presented and photometric comparison of the functioning of reflectors produced by different technologies is made. The sixth chapter is devoted to the analysis of the effects of light scattering in the system "radiation source + biological media + measuring tool" for different profiles of energy distribution in the laser beam and their effect on the relative illuminance distribution of photometric image at zone analysis for different layers of human skin. The influence the parameters of ellipsoidal reflectors on the boundary geometric properties of optical radiation in the forward and backscattered light is considered. The influence the diameter and power of the incident beam at the tasks of Raman spectroscopy by ellipsoidal reflectors is also substantiated. In the seventh chapter features of application the photometry by ellipsoidal reflectors for creation and improvement tools of biological and medical diagnostics and control are shown. The influence of the scattering anisotropy factor on the illuminance of photometric images and the possibility of biomedical goniophotometry were evaluated. A measurement system for angular photometry in backscattered light was developed and investigated. Based on the model experiment, the prospects of using a photometer with ellipsoidal reflectors to control the optical clearing of human skin were evaluated. A prototype optical non-invasive glucometer with ellipsoidal reflectors was created and its functional features were investigated. The eighth chapter discusses the prospects of applying the mirror ellipsoids of revolution method for various problems in optical biomedical diagnostics.
В работе решен комплекс задач, позволивший решить важную научно-прикладную проблему разработки метода построения и применения эллипсоидальных рефлекторов в системах регистрации и анализа рассеянного оптического излучения, а также апробации новых конструктивных, функциональных и медико-биологических решений. Это позволило теоретически и экспериментально обосновать метод и аппаратные средства применения эллипсоидальные рефлекторов для фотометрии светорассеяния биологическими средами при обнаружении их оптических свойств и идентификации физического и физиологического состояния. Предложено фундаментальную основу решения указанной проблемы за счет впервые разработанного механизма рей-трейсинга, что взаимно связывает параметры источника излучения, биологической среды, эллипсоидального зеркала и матричного приемника излучения в информационно-измерительной системе биомедицинского фотометра с эллипсоидальными рефлекторами, и который позволяет решать прямую и инверсную задачи распространения оптического излучения методом статистического моделирования Монте-Карло.

У роботі пропонується новий комплексний підхід до характеристики клітинної реактивності за допомогою еритроцитів в нормі та патології. Було застосувано два методи - мікрохвильових хвилеводів на основі діелектрометрії (39,5 ГГц) та осмотичної резистентності. Діелектрична реакція еритроцитів залежить від фізіологічного стану донорської крові, що знаходиться в прямій залежності від ступеня їх бета-рецепторної активності.
В работе предложен новый комплексный подход к характеристике клеточной реактивности с помощью эритроцитов в норме и патологии. Мы применили два метода - микроволновых волноводов на основе диэлектрометрии (39,5 ГГц) и осмотической резистентности. Диэлектрическая реакция эритроцитов зависит от физиологического состояния донорской крови, находящейся в прямой зависимости от степени их бета-рецепторной активности.
In the present work we propose a new integrated approach to characterization of cellular reactivity using human erythrocytes in health and disease. We have applied two methods – microwave waveguide-based dielectrometry (39.5 GHz) and osmotic fragility technique based on photometry – to monitor receptor-specific response of blood cells caused by the beta-blocker exposure. Our results showed that dielectric response of erythrocytes depends on the physiological state of blood donors that is in good agreement with the degree of their beta-receptors activity (beta-ARM index).

‘Techniques of medical sciences’ brings together a summary of the major techniques used experimentally in biomedical science research. These include those for molecular genetics (electrophoresis, DNA cloning and sequencing, and techniques for DNA and RNA research), proteomics (protein extraction, mass spectrometry, structural proteomics, and microscopy), cytology and histology including immunohistochemistry, microbiology (stains, cultures, serology, molecular techniques of microbiology, and testing for antibiotic resistance), biochemical assays (photometry and spectrophotometry, radioimmunoassay, ELISA, chromatography, flow cytometry, and fluorescence-activated cell sorting), and functional studies (in vitro, ex vivo, in vivo, stem cells, and clinical studies).