This paper presents the results of spectroscopic investigations on a synthetic dye solution with high fluorescence quantum yield and mixtures of this solution with colloidal silver particles. Basing on the results obtained the influence of the metal nano-particles presence on the changes of intensity and fluorescence quantum yield of the dye was determined. The purpose of the investigation was to determine the usefulness of fluoresceine in the structure of sensors and indicators of metal presence in the environment. The measurements were made for fluoresceine water solutions and its mixtures in
the ranges of concentrations from 10-6 M to 10-3 M. A significant growth of the fluorescence quantum yield in the presence of colloidal particles was only observed in the range of concentrations from 2•10-4 M to 8•10-4 M.
The molecular complementarity of two strands of the DNA double helix makes it possible to model changes in DNA sequences basing on their optical properties. The paper is devoted to problems with reliability of fluorescence analysis in investigating DNA chains. A given oligonucleotide library makes a matrix of integrated short sequences which all have their own location and base sequence. The fluorescence effects may be acquired using a CCD camera, converted to digital microimages and stored. In the paper the physical aspects of fluorescence phenomena have been described. The mathematical model for tests tending to determine optimum algorithms of oligonucleotide library detection are proposed. Application of selected algorithms of image processing has been analyzed for conditioning microimages. The results obtained of binarization using digital filtration are presented. The optimal algorithm of image binarization has been shown.
The subject of this paper concerns advanced techniques of procedures and imaging used in minimally invasive surgery and in non-operable cases of the alimentary tract tumor therapy. Examples of videoendoscopy and X-ray imaging used for the application of stents (prostheses) and catheters allowing for the performance of diagnostic and endo-therapeutic procedures are described. The possibility was indicated to elaborate a new method of proceeding in tumor therapy in the patients for whom the methods used so far were ineffective. In the paper examples of combined imaging the application of metallic stents and plastic catheters allowing for the performance of diagnostic and therapeutic procedures are presented. The cases shown refer to tumor located in the esophagus and in the bile and pancreatic ducts.
KEYWORDS: Systems modeling, Mathematical modeling, Blood, Data modeling, Transmittance, System identification, Signal generators, Optoelectronics, Dynamical systems, Photoplethysmography
The subject of this paper relates to the measurable effects of light behavior in biological materials. The modulations of biooptical signals, induced in tissues by arterial pulsations, are the basis of photoplethysmography (PPG), which by definition is an optoelectronic method for measuring and recording changes in volume of a body part. The PPG signal may be considered as the response of a given dynamic system to an input cyclical signal that is quasi-periodical. In the literature, the PPG attributes have been presented many times; however, the descriptions are mostly non-parametrical. On the contrary, a way of parametrical description using the methods that are utilized to identify dynamic systems is considered in this paper. A flow model and its mathematical description have been presented.
The subject of the paper is devoted to a modern diagnostic method called the endoscopic ultrasonography (EUS) that is still not widely implemented in many countries. This method bases on two imaging techniques: videoendoscopy and ultrasonography, making possible effective aiding of diagnostics as well as evaluating possibilities of performing radical surgical therapy. Rotating USG probes enable acquiring images vertical to an axis for the round angle area. Small diameters and adequate frequencies of these microprobes make possible their deep penetration into such difficult sites as the biliary and pancreatic ducts. The EUS advantages are presented here on the basis of several examples of real minimally invasive interventions as well diagnostic procedures practiced by the authors. EUS has allowed precise diagnostics without disturbances occurring at conventional ultrasound imaging. The presented images concern EUS used for examination of different digestive tract diseases, including biliary and pancreatic ducts.
An original semiconductor programmable light source has been designed and constructed. It consists of the controller module and the stabilized optical head comprising an optical feedback loop. The radiation emitted by the light source proposed can be generated in the continuous or pulse mode and its brightness can be adjustable in a wide range.
A labeled DNA sequence may be reconstructed by hybridization with a given number of complementary oligonucleotides included in a library. Such a library acts as an optical sensor, in which integrated elements emit signals make fluorescent microimages. Specificity of changes in optical density caused by specific interactions between pairs of DNA bases depends on the known nearest neighbor model that has been assumed here as the background. In the paper, problems concerned with optical detection and interpretation of changes in optical response, which can be induced by changes in a given DNA sequence composition, are presented. Reliability of the fluorescence image analysis in investigating the DNA chains is discussed. To know the standard set of microimages specifying the correct sequence composition, comparative studies of abnormal composition can be made by analysis of changes in light intensity occurring in particular sites of the library.
The subject of this paper is concerned with analysis of bio-optical signals to be acquired from a tissue slab exposed to selective transillumination. Changes in biophysical and optical parameters of the layered living tissue composition are considered to predict output results of occurring interactions. Especially, influence of changes in optical pathway on efficiency of light transmission through tissues is considered. Series of computer-aided simulation for a representative tissue set have been performed. On the background of data reported in the literature, the authors of this paper describe results collected by them during comparative analytical as well as experimental studies. Taking into account the 3-D approach to the object modeling, it was assumed that dimensions of the smallest component in the object structure are 10 μm x 10 μm x 10 μm. All layers were divided into such elementary cubes. During more than 100,000 simulations in a given direction, the effects of increase in the optical pathway were studied. Exemplary results of calculations for the transilluminated tissue slab are presented, at red light to be acting. The results are presented graphically, where specific changes in the transmittance intensity are given against the thickness of a given layer, which should be treated either optically thin or thick.
In this paper, a concept of an inexpensive PVDF pyroelectric radiation sensor of large aperture is described. The design details of a pyroelectric sensor based on the PVDF polymer are given. The preamplifier and conversion system of pyroelectric sensor signal are presented. Its photoresponse to short radiation pulses was investigated experimentally. Especially, influence of such parameters as frequency of optical pulses, width of pulses and temperature on the photoresponse of a given pyroelectric sensor was considered.
The subject of the paper is devoted to optoelectronic acquisition and processing of the pulse waveform of arterial blood, which contributes as the major component to peripheral photoplethysmographic signal. Considered questions concern problems with reliable processing of noninvasively acquired biooptical signals that are influenced by noises, artifacts and other disturbances. The proposed procedures of signal conditioning make possible effective acquisition of useful parameters of a raw noisy PPG signal. Novel design of the adherence circuit that allows eliminating the disturbing low-frequency trend has been presented. Results of verifying studies, where real signals acquired with transmission sensor were processed using this and circuit and classical linear circuit, are discussed.
KEYWORDS: Sensors, Signal processing, Digital filtering, Optical filters, Signal detection, Tissue optics, Blood, Linear filtering, Electronic filtering, Photoplethysmography
The subject of the paper is devoted to noninvasive acquisition of parameters specifying a photoplethysmographic signal (PPG) to which the pulse waveform contributes as the major component. Continuous monitoring ofphotoplethysmograms is of great importance in clinical practice. An optoelectronic sensor based either on reflection or transmission variant of lighttissue interaction can be used to detect the PPG signal, however, there are a lot of difficult measurement problems. Reliability of noninvasive optical sensing depends on specific factors, including physiological as well as technical interferences. In the paper, application of selected manners of digital filtration, which were used to process the raw signals acquired from an optoelectronic sensor placed on the fmgertip, is presented. The transmission variant oflight penetration is considered. The proposed procedures of signal conditioning allow making possible effective acquisition of useful parameters of a raw noisy PPG signal. Measurable quantitative changes caused by qualitative changes in a given pulse waveform shape and disturbances may be evaluated.
A metrological approach of some selected problems connected with the significant field of biomedical optics i.e., monitoring of arterial blood oxygenation by use of the tissues as optical media exposed to the controlled light action, has been presented. The subject of the measurements based on utilization of the selection absorption properties of blood is the hemoglobin oxygen saturation. Using optoelectronic sensing allows to convert sophisticated effects of noninvasive light-living tissue interaction to electrical signals which may be convenient to measure. Pulse oximetry which is based upon such a way of sensing and processing, is the recent advance in noninvasive oximetry. The unique advantages of that marvelous diagnostic technique have caused to recommend pulse oximeters as standard equipment in intensive care and other critical situations impending hypoxemia appearance. However, end-users of the pulse oximeters not always are aware of that these devices fall under specific limitations, of both physiological and technical nature. The author of this paper is a metrologist and deals mainly with various interdisciplinary problems of a measurement reliability including the aspects such as uncertainty of an outcome accessible to the user, causes affecting sensitivity, resolution and repeatability of processing function, and response time and stability of results. Referring to the subject discussed herein, and taking into account some open questions, the author's contribution is her own experience in modeling as well as in in vivo measuring of transilluminated living objects. A proposed novel use of the known pulse oximetry concept may be considered as complementary results against a general review background of the achievements obtained in oximetry as the state-of-the-art, and furthermore, the developing studies which are still in progress.
This paper is dedicated to computer-aided modeling of attributes of human tissues which are exposed to determined light action for measurement purposes. The transmission mode of light-tissue interaction is assumed. By use of either cross-section or longitudinal section of a multilayered tissue slab with planes perpendicular to the direction of light action, respectively, two dimensional representation of 3D structure is considered. In such an approach, effects resulting from light transmission can be studied for the light intensity vector in the rectangular coordinates. The proposed structure of a specialized algorithm makes it possible to create free variants of reference standards, including changes in a number of layers and their biophysical compositions. Exemplary results of calculations for the tissue slab transilluminated in x-y coordinates are presented, at red light to be acting. The major aim of further works is to carry out an atlas of variants modeling optical properties of living tissues which one could be a comprehensive source of standard data and real measurements based on utilization of light transmission through an object to be investigated.
Human body tissues are relatively translucent to penetrating light what makes possible to perform the effective transillumination for noninvasive measurements os some biophysical quantities by utilization of tissue optics. However, light is strongly attenuated by different tissue components and only proper processing of the transmitted fraction of light at the wavelengths included in the transillumination window, allows us to acquire measurable electrical signals. Volumes of living body parts are cyclically modulated according to the individual arterial pulsations. As a result, making transillumination of a sufficiently thin layer enables to observe rhythmical changes in light intensity transmitted by such an object. Optical density of blood and other tissues is very high, and so, values of light intensity components which are very low, cause many problems with reliability, sensitivity, and range of the detected selective changes. In order to choose a particular device and serve it properly, end-users of medical monitors should always know their advantages and limitations which can be of biophysical as well as technical nature. A lot of artifacts, noises, and disturbances affect the processing procedures and cause the decrease in useful output signals to be converted. On the other hand, there are many problems with empirical verification on human subjects. It is important to solve such complex questions because all the erroneous responses are potentially dangerous. One of the significant diagnostic problems is to detect global as well as local changes in tissue oxygenation which can appear for a lot of reasons. Basing on some novel light on use of the pulse oximetry idea, a model of the living object exposed to noninvasive transillumination can be considered in order to do technical recommendations useful in practice. Such an approach has been presented in the paper from the metrological point of view.
This paper is devoted to problems with reliability of the fluorescence analysis in investigating the DNA chains. Relationships between thermodynamic and optical properties of a given sequence are taken to consider modeling of a virtual light-directed library of oligonucleotides. Specificity of changes in optical density caused by specific interactions between pairs of DNA bases depends on the known nearest neighbor model which has been assumed here as the background. If to assume an integrated array of the known oligonucleotides (L-mers) which all have their own stable locations, after hybridization we may obtain a fluorescence result creating a matrix of micro-images; each one corresponds to the optical answer of a given oligonucleotide included in the investigated sequence spectrum. A presented concept of interpretation of fluorescence effects depends on relation between a given level of optical density and order of the bases included in oligonucleotides involved in hybridization procedure. The factors influencing fluorescence image attributes, including signal levels and stability as well as resolution and accuracy of sensing, are discussed. The obtained results of comparative computations made on a normal and simulated abnormal composition of a given human sequence are illustrated at the case that L = 6. Basing on consequences of changes in melting temperature, thermodynamic stability and levels of fluorescence light intensity, the optical spectra are presented as images made by sites of full hybridization put on a reference thermal map.
The subject of the paper concerns utilization of optical properties of a living object in noninvasive sensing of its attributes. The transmission type of light-tissue interaction is considered. Presented quantities express the optical phenomena caused by pulsatile nature of a living tissue set which makes the integral part of the measuring system. Two sets of the optical parameters such as the absorption, scattering and anisotropy coefficient, respectively, represent two-stage light propagation in a living optical medium; light losses are manifested by equivalent components of the optical density. Metrological requirements for reliable acquisition and processing of optical signals to estimate a given parameter of the transilluminated pulsatile object are specified. The transmission variant of pulse oximetry, which is the only optical method for monitoring blood oxygenation without blood drawing, is taken to illustrate more general problems. The achieved results may be useful in modeling effects of light-tissue interaction in order to make it possible to detect a quantitative or qualitative change in the living cuvette composition. As it was shown, 1D modeling can be applicable in noninvasive oximetry. Further studies will be focused on extension of the results to represent events in a living cuvette taking into account its spatial configuration.
Results of analyses and experiments concerning metrological problems with pulse oximetry principles that are utilized in noninvasive measurements of oxygen content in arterial blood, have been presented. Phenomena which limit processing reliability of the quantity to be sensed, i.e., the oxygen saturation SaO2%, are considered. Specific groups of affecting factors are distinguished in an approach of their contribution to the measurement uncertainty components. These factors are connected with properties of a living object to be measured, a way the optoelectronic sensor is applied, and external interferences, respectively. In comparative experiments, chosen models of pulse oximeters and the testing device especially made for the author's research, were used. The achieved results are being utilized in works on a design of the novel computer-aided system based on the pulse oximetry idea.
Specificity of a software package composed of two parts which control an optoelectronic sensor of the computer-aided system made to realize the noninvasive measurements of the arterial blood oxygen saturation as well as some parameters of the peripheral pulse waveform, has been described. Principles of the transmission variant of the one and only noninvasive measurement method, so-called pulse oximetry, has been utilized. The software co-ordinates the suitable cooperation of an IBM PC compatible microcomputer with the sensor and one specialized card. This novel card is a key part of the whole measuring system which some application fields are extended in comparison to pulse oximeters commonly attainable. The user-friendly MS Windows graphical environment which creates the system to be multitask and non-preemptive, has been used to design the specific part of the programming presented here. With this environment, sophisticated tasks of the software package can be performed without excessive complication.
The spectrophotometric technique used in pulse oximetry makes it possible to determine noninvasively and continuously the oxygen saturation of arterial blood. This
technique utilizes a set of the living blood-supplied tissues as an object to be measured. From the metrological point of view, the sensing efficiency, spectrophotometric processing quality, and object modelling are of great importance in reliable
solution of the specific interdisciplinary problems. In this paper the main results
of the authors studies concerning the optical part of measuring system have been
described against a background of the reviewed generally valid principles.
The spectrophotometric technique used in pulse oximetry makes it possible to measure the oxygen saturation of arterial blood noninvasively and continuously. The accuracy of pulse oximeters tends to decrease during extreme hypoxemia, and so the lowest values of the oxygen saturation can not be evaluated with known error, as yet. Furthermore, it is mostly in this range that many undesirable influences interfere with the measurement reliability. Thus, it can be helpful to observe and analyze what factors and to what extent they affect the applied processing procedures. The author of this paper describes the main results of her studies with the focus on the performances of the device specially made for her research.
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