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    Wyświetlanie 1-19 z 19
    Tytuł:
    Temperature Measurement by Statistical Parameters of Ultrasound Signal Backscattered from Tissue Samples
    Autorzy:
    Gambin, B.
    Kruglenko, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/1402186.pdf
    Data publikacji:
    2015-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    87.50.wp
    43.35.+d
    87.57.-s
    Opis:
    A novel estimation of temperature changes inside soft tissues has been proposed in sub-ablation range, i.e. ≈ 20°C-48°C. This estimation has been obtained by studying statistical properties of backscattered ultrasonic signals. Two different procedures of heating/cooling have been performed in which the RF echoes have been registered from soft tissue phantom in the first procedure, and from soft tissue in vitro in the second one. Calculated envelopes of signals registered in time points during heating/cooling experiments have been treated as a statistical sample drawn from a random variable with three different distributions, namely the Rayleigh distribution, the Nakagami distribution, and the K-distribution. The histograms obtained in subsequent time moments have been fitted to the three distributions. Dependencies of their shape and scale parameters on temperature have been calculated. It is concluded that the shape parameter of the K-distribution can be chosen as the best marker of temperature changes in both experiments. The choice of the marker has been made by analysis of temperature dependencies of all calculated parameters and by comparing the quality of fitting all histograms to the considered distributions. Besides, the chosen marker as a function of temperature exhibits the closest shape to temperature/time function experimentally measured.
    Źródło:
    Acta Physica Polonica A; 2015, 128, 1A; A-72-A-78
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Some aspects of numerical modeling of temperature increase due to ultrasound beam irradiation of rat liver
    Autorzy:
    Kruglenko, E.
    Gambin, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/331800.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    Some aspects of FEM modeling of hyperthermia, the procedure of tissue temperature rise above 37 oC inside the living organism, as a treatment modality, are studied. Low intensity focused ultrasound (LIFU) beam has been used as a source of temperature rise in the liver tissue during performed experiments in vitro. The comparison of the FEM model of the corresponding heating process and the experimental results has been presented in [1]. In the paper, the FEM model of heating scheme of the rat liver tissue in vivo irradiated by the same ultrasound transducer is formulated. At first, the existence of blood perfusion is taken into account in the model equation. Secondly, the thermal and acoustical properties, which are the input parameters of the numerical model, are taken from the published data in literature. Here, the size and the intensity of heat sources are modeled in two ways on the basis of acoustic nonlinear equation solutions in 3 layers attenuating medium. We demonstrate how the results of FEM model in the case of in vitro and in vivo heating, depend on the assumed power density of heat sources, as well as on the size of the heated area. The results are compared and discussed. The influence of different models on temperature rise profiles are demonstrated.
    Źródło:
    Hydroacoustics; 2011, 14; 99-110
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Temperature detection based on nonparametric statistics of ultrasound echoes
    Autorzy:
    Byra, M.
    Gambin, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/332315.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    noninvasive temperature monitoring
    nonparametric statistics
    ultrasound backscattering
    Opis:
    Different ultrasound echoes properties have been used for the noninvasive temperature monitoring. Temperature variations that occur during heating/cooling process induce changes in a random process of ultrasound backscattering. It was already proved that the probability distribution of the backscattered RF (radio frequency) signals is sensitive to the temperature variations. Contrary to previously used methods which explored models of scattering and involved techniques of fitting histograms to a special probability distribution two more direct measures of changes in statistics are proposed in this paper as temperature markers. They measure the ''distance'' between the probability distributions. The markers are the Kolmogorov Smirnov distance and Kulback-Leiber divergence. The feasibility of using such nonparametric statistics for non- invasive ultrasound temperature estimation is demonstrated on the ultrasounds data collected during series of heating experiments in which the temperature was independently registered by the classical thermometer or thermocouples.
    Źródło:
    Hydroacoustics; 2015, 18; 17-23
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Incompressible limit for a magnetostrictive energy functional
    Autorzy:
    Gambin, B.
    Bielski, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/201841.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    gamma-convergence
    incompressibility
    magnetostrictive material
    second gradient of deformation
    existence of minimizers
    Opis:
    The modern materials undergoing large elastic deformations and exhibiting strong magnetostrictive effect are modelled here by free energy functionals for nonlinear and non-local magnetoelastic behaviour. The aim of this work is to prove a new theorem which claims that a sequence of free energy functionals of slightly compressible magnetostrictive materials with a non-local elastic behaviour, converges to an energy functional of a nearly incompressible magnetostrictive material. This convergence is referred to as a Γ -convergence. The non-locality is limited to non-local elastic behaviour which is modelled by a term containing the second gradient of deformation in the energy functional.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 4; 1025-1030
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ultrasonic Synthetic Apertures: Review
    Autorzy:
    Nowicki, A.
    Gambin, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/176456.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    synthetic aperture
    effective aperture
    ultrasonography
    Opis:
    In the paper the concept of synthetic aperture used for high resolution/high frame rate ultrasonic imaging is reviewed. The synthetic aperture technique allows building extended “virtual” apertures, synthesized from smaller real aperture resulting in improved lateral resolution along full penetration depth without sacrificing the frame rate. Especially, four methods, synthetic aperture focusing (SAF), multi-element synthetic aperture focusing (M-SAF), synthetic receive aperture (SRA) and synthetic transmit aperture (STA) are addressed. The effective aperture function, describing two-way, far field radiation is a useful tool in beam pattern analysis. Some basic notations, which are used to calculate the effective aperture are introduced in Appendix.
    Źródło:
    Archives of Acoustics; 2014, 39, 4; 427-438
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Statistical properties of wavelet transform coefficients of backscattering signal from soft tissues and their phantoms
    Autorzy:
    Gambin, B.
    Doubrovina, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/331908.pdf
    Data publikacji:
    2013
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    The paper contains the wavelet approach to registered backscattered RF signals from two different cases. First, the wavelet analysis has been performed for RF signals registered from soft tissue phantoms. The second case is the wavelet analyses of RF scattered signals from regions of healthy and BCC changed human skin. The three phantoms made from tissuemimicking material with different structures have been measured. We claim that there are visible differences in the statistical parameters of wavelets coefficients of signals between healthy and BCC changed skin regions as well as between phantoms without scatterers and with different number of strong small scatterers.
    Źródło:
    Hydroacoustics; 2013, 16; 59-66
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    RF signal amplitude statistics during temperature changes in tissue phantoms
    Autorzy:
    Kruglenko, E.
    Gambin, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/332743.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    Two heating protocols for soft tissue phantoms have been performed. An Agar-Gel-Oil (AGO) mixture has been heated locally by applying ultrasonic beams and a Poly Vinyl Alcohol-cryogel (PVA-c) has been heated “globally” by a water bath with a controlled temperature rise. The RF signals were collected during heating by an ultrasound transducer to ensure no interference from waves from the heating transducer. Independently, the thermocouples' measurement has been used to obtain temperature as a function of time in the AGO case. At first, a compensation of attenuation was performed and normalized envelopes of signals were used as data for statistical analysis. It is shown that random the values of the backscattered amplitude are close to Rayleigh and K-distributed random variables for AGO and PVA-c, respectively. Temperature is linked to the scale parameter of Rayleigh distribution for the AGO, and the shape parameter of K-distribution for PVA-c were calculated and discussed in the context of their suitability for the acoustic measurement of temperature.
    Źródło:
    Hydroacoustics; 2014, 17; 115-122
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    BEM and Shear lag method for interface problem of bi-material structure under static loading
    Metoda Elementów Brzegowych i metoda "shear lag" w zagadnieniu delaminacji dwuwarstwowej struktury pod wpływem statycznego obciążenia
    Autorzy:
    Valeva, V.
    Ivanova, J.
    Gambin, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/280619.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    BEM
    Shear lag analysis
    bi-material structure
    debond length
    Opis:
    The behaviour of the interface of a pre-cracked bi-material ceramic-metal structure under static axial loading is an object of interest in the present paper. To solve the problem for interface delamination of the structure and to determine the debond length along the interface, a 2D BEM code was created and applied. The interface plate is assumed as a very thin plate comparing with the others two. The parametric (geometric and elastic) analysis of the debond length and interface shear stress is done. First, the obtained numerical results are compared with analytical ones from 1D. Shear lag analysis of the considered structure. The respective comparison is illustrated in figures and shows a good agreement. The comparison between the calculated using 2D BEM code elastic-brittle debond lengths with Song's experimental data for the bi-material structure Zinc/Steel as well as with respective results from FEM simulation shows good coincidence.
    W pracy badano zachowanie się na granicy pomiędzy warstwami metalu i ceramiki pod wpływem statycznego obciążenia przyłożonego w kierunku równoległym do połączenia pasm, w przypadku istnienia początkowego nacięcia w jednej z warstw prostopadłego do powierzchni połączenia. W celu rozwiązania zagadnienia delaminacji wzdłuż powierzchni łączącej oba materiały i wyznaczenia długości odspojenia został stworzony i zastosowany kod Metody Elementów Brzegowych – zagadnienie 2-wymiarowe. Warstwa łącząca dwa materiały została potraktowana jako bardzo cienka płyta, w porównaniu do grubości obu warstw materiałowych. Przeprowadzono parametryczną (geometrycznaą i sprężystą) analizę długości odspojenia (delaminacji) i naprężenia stycznego. Otrzymane rezultaty numeryczne porównano z analitycznymi rozwiązaniami 1-wymiarowej analizy tzw. metodą "shear lag". Otrzymane wyniki, zilustrowane na rysunkach, wykazują wzajemną zgodność. Pokazano również, że wyniki uzyskane przy użyciu Metody Elementów Brzegowych są zgodne z wynikami eksperymentu Song'a przeprowadzonego dla dwuwarstwowego elementu kompozytowego pomiędzy warstwą cynku i stali, a także z wynikami uzyskanymi w Metodzie Elementów Skończonych.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2011, 49, 1; 17-29
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Differentiation of random structure properties using wavelet analysis of backscattered ultrasound
    Autorzy:
    Gambin, B.
    Wojcik, J.
    Doubrovina, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/331612.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    spectrogram
    scalogram
    wavelets
    random scattering structure
    Opis:
    The aim of this work was to find the differences between random media by analyzing the properties of the ultrasound signals backscattered from the inhomogeneities. A numerical model is used to generate two types of random media. The first has the randomness in scatterers’ positions and the second has the randomness in the size and acoustical properties of scatterers. The numerical model of wave scattering has been used to simulate the RF (radio frequency) signals caused by the incident pulse traveling as a plane wave. The markers of randomness type differences between the scattering media were obtained with the help of the spectral and wavelet analysis. The effect of differences in randomness type is more spectacular when the wavelet analysis is performed.
    Źródło:
    Hydroacoustics; 2016, 19; 121-128
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Relationships between acoustical properties and stiffness of soft tissue phantoms
    Autorzy:
    Gambin, B.
    Kruglenko, E.
    Byra, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/332049.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    soft tissue phantoms
    elastography
    ultrasound attenuation
    speed of sound
    Nakagami maps
    stiffness
    Opis:
    Polyvinyl-alcohol cryogel is commonly used for soft tissue phantom manufacture. The gel formation from an aqueous solution of polyvinyl-alcohol takes place during the freezing and thawing cycle. The aim of this work was to assess the degree of gel solidification, hence the material stiffness, by means of quantitative ultrasound. We manufactured three phantoms which differed in the number of freezing/thawing cycles. First, tissue phantoms were examined with an elastography technique. Next, we measured the speed of sound and the attenuation coefficient. What is more, the inter structure variations in phantoms were assessed with the Nakagami imaging which quantifies the scattering properties of the backscattered ultrasound echo. Obtained results confirmed the connection between the number of freezing/thawing cycles and the solidification p rocess. We d efined th e bo undary layer as a region which has a different structure than the sample interior. Next, for each phantom this layer was extracted based on a Nakagami parameter map. We calculated that the thickness of the boundary layer was lower in samples which were subjected to a larger number of freezing/thawing cycles.
    Źródło:
    Hydroacoustics; 2016, 19; 111-120
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Relationship between thermal and ultrasound fields in breast tissue in vivo
    Autorzy:
    Gambin, B.
    Kruglenko, E.
    Wójcik, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/332806.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    backscattered ultrasonic signal
    non-uniform temperature field
    Opis:
    The study shows the direct relationship between the temperature field and the parallel changes that are taking place in backscattered ultrasonic signals from the breast tissue in vivo when heated to the temperature of approximately 42 deg. C. The non-uniform temperature field inside the heating tissue was determined by the numerical model using FEM. It is shown that the spatial distribution of intensities of the backscattered signals coincides with the temperature distribution field predicted by the numerical model in some areas. The result indicates the possibility of the indirect measurement of the temperature rise in the breast tissue in vivo by measuring the intensity variations of the ultrasound echo.
    Źródło:
    Hydroacoustics; 2015, 18; 53-58
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Temperature level and properties of wavelet approximations of backscattered ultrasound
    Autorzy:
    Doubrovina, O.
    Gambin, B.
    Kruglenko, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/331549.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    The aim of the paper is to find links between the dynamics of changes of statistical parameters and changes in spectral properties of the signal envelope of backscattered RF signals during the thermal process. We have shown previously that by using wavelet approximations these tendencies are better recognized in the case of the heating of a phantom sample than in the parallel analysis performed for a full signal envelope. Here we are currently expanding this statement to the case of heating a soft tissue sample in vitro. The shape parameter of the K- distributed random variable is considered as a statistical marker of temperature level changes. Additionally, the spectral properties of different levels of wavelet approximations are calculated and their sensitivity to temperature increase and decrease is demonstrated. Both approaches registering changes in temperature, are used in the case of the pork loin tissue sample in vitro, heated by an ultrasound beam with a different power.
    Źródło:
    Hydroacoustics; 2014, 17; 37-46
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Soft tissue-mimicking materials with various number of scatterers and their acoustical characteristics
    Autorzy:
    Kruglenko, E.
    Gambin, B.
    Cieślik, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/331726.pdf
    Data publikacji:
    2013
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    For the study of the temperature increase in the soft tissues irradiated by a low-power ultrasound [1], soft tissue-mimicking materials can be used. The phantoms have been produced based on an aqueous solution of agar, oil, and glass beads microparticles. The RF signals collected in the experiments enabled evaluation of the acoustic properties of phantoms with different number of strong scatterers (concentration varied from 0 to 30 pcs/mm3). Speed of sound (SOS) determined for the phantoms was similar to the value typical of soft tissue (about 1540 m/s). To determine attenuation coefficient the semi-transmission method has been used. Attenuation coefficient value varied from 0.5 to 1.1 dB/(MHz cm), depending on the number of scatterers. It was shown that the phantoms stored for 6 months preserved their acoustical properties and were usable for further experiments. It was found that within the total attenuation, the part corresponding to scattering can be distinguished.
    Źródło:
    Hydroacoustics; 2013, 16; 121-128
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Theoretical results and numerical study on the nonlinear reflection and transmission of plane sound waves
    Autorzy:
    Wojcik, J.
    Gambin, B.
    Litniewski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/332766.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    theoretical and numerical model
    continuity conditions
    non-linear waves
    lossy media
    Opis:
    The comparison between theoretical and numerical solutions of the reflection/transmission problem for the acoustic plane wave normally incident on the discontinuity surface between two nonlinear lossy media was presented. Numerical calculations made under the assumption that the two media have the same impedance, allow to single out the effect of nonlinearities in the description of the reflection and transmission phenomena, so they agreed with theoretical predictions. It was shown that theoretically obtained and numerically calculated results mutually confirmed themselves.
    Źródło:
    Hydroacoustics; 2015, 18; 181-192
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Temperature Monitoring during Focused Ultrasound Treatment by Means of the Homodyned K Distribution
    Autorzy:
    Byra, M.
    Kruglenko, E.
    Gambin, B.
    Nowicki, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032313.pdf
    Data publikacji:
    2017-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    temperature monitoring
    homodyned K distribution
    focused ultrasound
    Opis:
    Temperature monitoring is essential for various medical treatments. In this work, we investigate the impact of temperature on backscattered ultrasound echo statistics during a high intensity focused ultrasound treatment. A tissue mimicking phantom was heated with a spherical ultrasonic transducer up to 56°C in order to imitate tissue necrosis. During the heating, an imaging scanner was used to acquire backscattered echoes from the heated region. These data was then modeled with the homodyned K distribution. We found that the best temperature indicator can be obtained by combining two parameters of the model, namely the backscattered echo mean intensity and the effective number of scatterers per resolution cell. Next, ultrasonic thermometer was designed and used to create a map of the temperature induced within the tissue phantom during the treatment.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 6; 1525-1528
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Applying crystallography in analysis of trabecular bone backscatter
    Autorzy:
    Wojcik, J.
    Litniewski, J.
    Nowicki, A.
    Gambin, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/332506.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Opis:
    Some important details of the Backscatter Effective Cross-Sections obtained for random scattering structures (like trabecular bone) are explain by comparison with the results obtained by means of the simplified theoretical model. The simplified model was (establish) and justified on the basis of the structural analysis of the results obtained for exact model of the field scattering on complex structures. The simplified model is commonly used in description of the scattering on the regular structures like crystal. Comparison with experimental results for the trabecular bone is also presented. The results allowed to conclude that crystallographic methods could be potentially useful for extracting characteristic features of trabecular bone.
    Źródło:
    Hydroacoustics; 2011, 14; 255-266
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modeling of Tissues in vivo Heating Induced by Exposure to Therapeutic Ultrasound
    Autorzy:
    Gambin, B.
    Kruglenko, E.
    Kujawska, T.
    Michajłow, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1504201.pdf
    Data publikacji:
    2011-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    87.50.wp
    Opis:
    The aim of this work is mathematical modeling and numerical calculation in space and time of temperature fields induced by low power focused ultrasound beams in soft tissue in vivo after few minutes exposure time. These numerical predictions are indispensable for planning of various ultrasound therapeutic applications. Both, the acoustic pressure distribution and power density of heat sources induced in tissue, were calculated using the numerical solution to the second order nonlinear differential wave equation describing propagation of the high intensity acoustic wave in three-layer structure of nonlinear attenuating media. The problem of the heat transfer in living tissues is modelled by the Pennes equation, which accounts for the effects of heat diffusion, blood perfusion losses and metabolism rate. Boundary conditions and geometry are chosen according to the anatomical dimensions of a rat liver. The obtained results are compared with those calculated previously and verified experimentally for temperature elevations induced by ultrasound in liver samples in vitro. The analysis of the results emphasizes the value of the blood perfusion and the values of heat conductivity on the temperature growth rate. The numerical calculations of temperature fields were performed using the ABAQUS FEM software package. The thermal and acoustic properties of the liver and water being the input parameters to the numerical model were taken from the published data in cited references. The range of thermal conductivity coefficient of living tissue is obtained from the model of two-phase composite medium with given microstructure. The first component is a "solid" tissue and the second one corresponds to blood vessels area. The circular focused ultrasonic transducer with a diameter of 15 mm, focal length of 25 mm and resonance frequency of 2 MHz has been used to generate the pulsed ultrasonic beam in a very introductory experiment in vivo, which has been performed. Numerical prediction confirms qualitatively its results.
    Źródło:
    Acta Physica Polonica A; 2011, 119, 6A; 950-956
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of ultrasound to noninvasive imaging of temperature distribution induced in tissue
    Autorzy:
    Karwat, P.
    Kujawska, T.
    Secomski, W.
    Gambin, B.
    Litniewski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/332286.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    HIFU
    echo phase shift
    parametric imaging
    velocity/brightness CNR
    Opis:
    Therapeutic and surgical applications of High Intensity Focused Ultrasound (HIFU) require monitoring of local temperature rises induced inside tissues. It is needed to appropriately target the focal plane, and hence the whole focal volume inside the tumor tissue, prior to thermo-ablative treatment, and the beginning of tissue necrosis. In this study we present an ultrasound method, which calculates the variations of the speed of sound in the locally heated tissue. Changes in velocity correspond to temperature change. The method calculates a 2D distribution of changes in the sound velocity, by estimation of the local phase shifts of RF echo-signals backscattered from the heated tissue volume (the focal volume of the HIFU beam), and received by an ultrasound scanner (23). The technique enabled temperature imaging of the heated tissue volume from the very inception of heating. The results indicated that the contrast sensitivity for imaging of relative changes in the sound speed was on the order of 0.06%; corresponding to an increase in the tissue temperature by about 2 °C.
    Źródło:
    Hydroacoustics; 2016, 19; 219-228
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ultrasonic Measurement of Temperature Rise in Breast Cyst and in Neighbouring Tissues as a Method of Tissue Differentiation
    Autorzy:
    Gambin, B.
    Byra, M.
    Kruglenko, E.
    Doubrovina, O.
    Nowicki, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/177465.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    medical ultrasound
    temperature changes in vivo
    breast tissue
    ultrasonic temperature measurement
    Opis:
    Texture of ultrasound images contain information about the properties of examined tissues. The analysis of statistical properties of backscattered ultrasonic echoes has been recently successfully applied to differentiate healthy breast tissue from the benign and malignant lesions. We propose a novel procedure of tissue characterization based on acquiring backscattered echoes from the heated breast. We have proved that the temperature increase inside the breast modifies the intensity, spectrum of the backscattered signals and the probability density function of envelope samples. We discuss the differences in probability density functions in two types of tissue regions, e.g. cysts and the surrounding glandular tissue regions. Independently, Pennes bioheat equation in heterogeneous breast tissue was used to describe the heating process. We applied the finite element method to solve this equation. Results have been compared with the ultrasonic predictions of the temperature distribution. The results confirm the possibility of distinguishing the differences in thermal and acoustical properties of breast cyst and surrounding glandular tissues.
    Źródło:
    Archives of Acoustics; 2016, 41, 4; 791-798
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-19 z 19

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