Wyniki wyszukiwania - BazTech

1

Symulator parametrów rezystancyjnych tkanek do badań bioimpedancyjnych

Piekar E., Sobotnicki A.

Pomiary Automatyka Kontrola

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2014

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R. 60, nr 12

1181--1184

PL

Metodę bioimpedancyjną stosuje się w fizjologii i medycynie klinicznej. Opiera się ona na pomiarze i analizie impedancji elektrycznej żywych tkanek. W pracy przedstawiono sposób implementacji metody bioimpedancyjnej w ocenie zmian objętościowych w układzie krążenia oraz modele stosowane do opisu parametrów elektrycznych naturalnych tkanek. Przedstawiono również zadajnik Reotester symulujący parametry rezystancyjne tkanek opracowany na potrzeby badań aparatury do pomiarów bioimpedancyjnych.

EN

Bioimpedance method is used in clinical medicine and physiology. It is based on the measurement and analysis of electrical impedance of living tissues. This method provides, inter alia, a lot of information about the processes occurring in the circulation and breathing, and its big advantage is noninvasiveness. The paper presents a way of implementing the bioimpedance method in assessment of volume changes in the circulatory system, and the models used to describe the electrical parameters of natural tissues. It also presents the Reotester simulator used to simulate the impedance parameters of the tissues. The simulator allows to generate a constant resistive component of the impedance, modulated by sinusoidal or trapezoidal signal of variable resistance component. The established values of the simulation parameters correspond to the actual ranges of impedance module in the cardio - plethysmographic measurements. The electrical circuit of the simulator consists of a constant resistance in parallel connection with a dedicated photo-resistive element for generating variable component of the resistance. This paper describes the way of implementation of the simulated resistance, the construction of photo-resistive element, and the results of testing and calibration of the simulator. Described simulator is useful tool both, when testing a newly developed device for bioimpedance measurements, as well as for servicing the equipment in the clinical conditions.

2

Segmentation of images using gradient methods and polynomial approximation

Piekar E., Momot M., Momot A.

Journal of Medical Informatics & Technologies

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2014

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Vol. 23

95--102

EN

The paper presents a method for segmentation of images using region growing, with modification through the use of a correction coefficient based on the variation of intensity (brightness) in the neighborhood of the pixel of the interest. A method for the quantification of variability is based on differences in intensity, as well as the differences in intensity gradients in the surrounding pixels [10]. Evaluation of the gradients were determined by means of numerical differentiation, using the polynomial approximation [11]. The article presents the effects of application of developed methods for segmentation of images of the brain, lungs and heart.

3

Application of region growing method to brain tumor segmentation - preliminary results

Piekar E., Szwarc P., Sobotnicki A., Momot M.

Journal of Medical Informatics & Technologies

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2013

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Vol. 22

153--160

EN

In this article image have been subject to segmentation using Matlab software, i.e. T1 in normal conditions, perfusion images and images after administering a contrast agent. The tumor in images made in normal conditions was difficult to identify. The images obtained after administering the contrast agent confirmed that the homogeneity criterion has been appropriately selected. In perfusion images the pixels of the background were added to the tumor. When the parameters were changed i.e. pixel counter or neighborhood type the method became more efficient; the tumor boundaries were outlined more precisely. The region growing method enables precise tumor detection; however, the selection of an appropriate homogeneity criterion is a prerequisite for correct segmentation.

4

Analysis of reasons causing development of malfunctioning software in medical equipment

Drewniok L., Piekar E., Stasiak M., Maniura R.

Journal of Medical Informatics & Technologies

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2012

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Vol. 21

57--63

EN

In the world today, the vast majority of medical electronic equipment contains software. Very often even the computer software is classified as an independent medical part. Because of the ease of making changes to the element of a large functional complexity, there is a high risk of introducing errors in the modified software. For example, just entering the wrong one filter parameter can make the biomedical signal processing circuit work incorrectly. As noted in [5], "the lessons learned from … disasters can do more to advance engineering knowledge than all the successful machines and structures in the world". This statement is also true in the software domain. The main goal of this paper is - basing on a database of medical devices with software defects - to draw conclusions and guidance for the design and maintenance of software for new medical equipment.