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Tytuł:
Example of Structure Modeling and Analysis of Ultrasound Scattering for Trabecular Bone
Autorzy:
Wójcik, J.
Litniewski, J.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/177853.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
multi-scattering
random complex structures
trabecular bone model
Opis:
A trabecular bone consists of trabeculae whose mechanical properties differ significantly from the surrounding marrow, therefore an ultrasonic wave propagating within the bone structure is strongly scattered. The aim of this paper was to evaluate the contribution of the first, second and higher order scattering (multiple scattering) into the total scattering of ultrasound in a trabecular bone. The scattering due to the interconnections between thick trabeculae, usually neglected in trabecular bone models, has been also studied. The basic element in our model of the trabecular bone was an elastic cylinder with a various finite-length and diameter as well as orientation. The applied model was taking into account variation of both, elements size and their spatial configuration. The field scattered on the bone model was evaluated by solving numerically the integral form of the generalized Sturm-Liouville equation describing a scalar wave in inhomogeneous and lossy media. For the scattered fields calculated numerically the effective cross-sections were determined. The influence of absorption on the scattering coefficients was demonstrated. The results allowed to conclude that within the frequency range from 0.5 to 1.5 MHz contribution of the second order scattering to the effective backscattering cross-section is at least 500 times lower than that due to the first order scattering. It was noticed that for a frequency higher than 1.5 MHz fast growth of the backscattering (reflection) coefficients, calculated for the second order scattering, occurs.
Źródło:
Archives of Acoustics; 2010, 35, 4; 701-713
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multiple scattering contribution to trabecular bone backscatter
Autorzy:
Wójcik, J.
Litniewski, J.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/332838.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
bone backscatter
integral equations
spectral distribution
Opis:
Integral equations that describe scattering on the structure with step rise parameters, have been numerically solved on example of the trabecular bone model. The model consists of several hundred elements with randomly selected parameters. The spectral distribution of scatter coefficients in subsequent orders of scattering has been presented.
Źródło:
Hydroacoustics; 2009, 12; 227-236
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tissue Attenuation Estimation from Backscattered Ultrasound Using Spatial Compounding Technique - Preliminary Results
Autorzy:
Klimonda, Z.
Litniewski, J.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/177842.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ultrasound attenuation estimation
spatial compounding
parametric imaging
Opis:
The pathological states of biological tissue are often resulted in attenuation changes. Thus, information about attenuating properties of tissue is valuable for the physician and could be useful in ultrasonic diagnosis. We are currently developing a technique for parametric imaging of attenuation and we intend to apply it for in vivo characterization of tissue. The attenuation estimation method based on the echoes mean frequency changes due to tissue attenuation dispersion, is presented. The Doppler IQ technique was adopted to estimate the mean frequency directly from the raw RF data. The Singular Spectrum Analysis technique was used for the extraction of mean frequency trends. These trends were converted into attenuation distribution and finally the parametric images were computed. In order to reduce variation of attenuation estimates the spatial compounding method was applied. Operation and accuracy of attenuation extracting procedure was verified by calculating the attenuation coefficient distribution using the data from the tissue phantom (DFS, Denmark) with uniform echogenicity while attenuation coefficient underwent variation.
Źródło:
Archives of Acoustics; 2010, 35, 4; 643-651
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Parametric sonographic imaging - application of synthetic aperture technique to imaging attenuation of ultrasound in tissue structures
Autorzy:
Litniewski, J.
Klimonda, Z.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/331882.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Ultrasonic imaging is a well-established technique in medicine. However, in most conventional applications of clinical ultrasonic scanners only the peak amplitude echogenicity is used to create the image. Moreover, signal envelope detection destroys potentially useful information about frequency dependence of acoustic properties of tissue comprised in RF backscattered echoes. We have explored the possibility of developing the method of imaging the distribution of the acoustic attenuation in tissue. We expect that the method will help in localization of the pathological states of tissue including tumors and diffuse liver diseases. The spatial resolution and precision of the method are crucial for medical diagnosis, hence the synthetic aperture technique was applied for ultrasonic data collection. The final goal of the presented project is to develop reliable diagnostic tool, which could be implemented in standard USG systems, as the new visualization mode.
Źródło:
Hydroacoustics; 2012, 15; 99-110
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preliminary results of attenuation estimation from tissue backscatter using commercial ultrasonic scanner
Autorzy:
Klimonda, Z.
Litniewski, J.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/331943.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Ultrasonography (USG) is a widespread and powerful tool used successfully in modern diagnostics. The standard USG scanner reflects impedance variations within the tissue that is penetrated by the ultrasound pulse. Although such image provides a lot of information to the physician, there are another parameters which could be imaged. The attenuation coefficient is one of them. Imaging of attenuation seems to be a promising tool for ultrasonic medical diagnostics. The attenuation estimation method based on the echoes mean frequency changes due to tissue attenuation dispersion is presented. The Doppler IQ technique is adopted to estimate the mean frequency changes directly from the raw RF data. The Singular Spectrum Analysis (SSA) technique is used for the mean frequency trend extraction. The changes of the mean frequency trend are related directly to the local attenuation coefficient. Preliminary results of the tissue phantom attenuation coefficient estimation and imaging using the commercial scanner are presented.
Źródło:
Hydroacoustics; 2010, 13; 127-134
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthetic Aperture Technique Applied to Tissue Attenuation Imaging
Autorzy:
Klimonda, Z.
Litniewski, J.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/176945.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
tissue attenuation imaging
synthetic aperture
diagnosis enhancing
Opis:
The attenuating properties of biological tissue are of great importance in ultrasonic medical imaging. Investigations performed in vitro and in vivo showed the cor- relation between pathological changes in the tissue and variation of the attenuation coefficient. In order to estimate the attenuation we have used the downshift of mean frequency (fm) of the interrogating ultrasonic pulse propagating in the medium. To determine the fm along the propagation path we have applied the fm estimator (I/Q algorithm adopted from the Doppler mean frequency estimation technique). The mean-frequency shift trend was calculated using Single Spectrum Analysis. Next, the trends were converted into attenuation coefficient distributions and finally the parametric images were computed. The RF data were collected in simulations and experiments applying the synthetic aperture (SA) transmit-receiving scheme. In measurements the ultrasonic scanner enabling a full control of the transmission and reception was used. The resolution and accuracy of the method was verified using tissue mimicking phantom with uniform echogenicity but varying attenuation coefficient.
Źródło:
Archives of Acoustics; 2011, 36, 4; 927-935
0137-5075
Pojawia się w:
Archives of Acoustics
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:
Ultrasound imaging of stiffness with two frequency pulses
Autorzy:
Nowicki, A.
Byra, M.
Litniewski, J.
Wójcik, J.
Powiązania:
https://bibliotekanauki.pl/articles/332602.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Nowadays there are new modalities in ultrasound imaging allowing better characterization of tissue regions with different stiffness. We are proposing a novel approach based on compression and rarefaction of tissue simultaneously with imaging. The propagating wave is a combination of two pulses. A low frequency pulse is expected to change the local scattering properties of the tissue due to compression/rarefaction while a high frequency pulse is used for imaging. Two transmissions are performed for each scanning line. First, with the imaging pulse that propagates on maximum compression caused by a low frequency wave. Next, the low frequency wave is inverted and the imaging pulse propagates over the maximum rarefaction. After the processing of the subtracted echoes from subsequent transmissions including wavelet transform and band-pass filtering, differential images were reconstructed. The low frequency wave has a visible impact on the scattering properties of the tissue which can be observed on a differential image.
Źródło:
Hydroacoustics; 2014, 17; 151-160
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Golays codes sequences in ultrasonography
Autorzy:
Nowicki, A.
Trots, I.
Secomski, W.
Litniewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/332137.pdf
Data publikacji:
2004
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The issue of maximizing penetration depth with concurrent retaining or enhancement of image resolution constitutes one of the time invariant challenges in ultrasound imaging. Concerns about potential and undesirable side effects set limits on the possibility of overcoming the frequency dependent attenuation effects by increasing peak acoustic amplitudes of the waves probing the tissue. To overcome this limitation a pulse compression technique employing 16 bits Complementary Golay Code (CGS) was implemented at 4 MHz. In comparison with other, earlier proposed, coded excitation schemes, such as chirp, pseudo-random chirp and Barker codes, the CGS allowed virtually side lobe free operation. Computer simulation results for CGS pulse compression are presented. Next three different methods and algorithms used to calculate the pairs of Golay sequences of the different length are described. Experimental results are presented in the form, which in clear way illustrates the resolution, signal penetration and contrast dynamics of ultrasonic images obtained by using Golay coded excitation.
Źródło:
Hydroacoustics; 2004, 7; 173-182
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of trabecular bone properties using ultrasonic scanne
Autorzy:
Cieślik, L.
Litniewski, J.
Lewandowski, M.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/331888.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Signals scattered in trabecular bone contain information about properties of the bone structure. Evaluation of this properties may be essential for osteoporosis diagnosis and treatment monitoring because the standard densitometry does not provide complete information about the bone strength. It was previously demonstrated that using numerical model of backscattering in trabecular bone it is possible to estimate some microstructural characteristics of bone. Model predicts departures from the Rayleigh statistics of the scattered signal envelope depended on the scatterer physical parameters and its shape uniformity. This study concerns examination of trabecular bone (calcaneus) in vivo. Ultrasonic bone scanner operating at frequency of 1,5 MHz was used to collect backscattered signals. Data were processed in order to obtain the statistical properties of the signal envelope and to compare them with histograms resulting from modeling. This study is an approach towards developing a tool for the investigation of scattering in trabecular bone that can potentially provide clinically useful information about bone strength and condition.
Źródło:
Hydroacoustics; 2010, 13; 39-52
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Statistical analysis of ultrasound echo for skin lesions classification
Autorzy:
Piotrzkowska, H.
Litniewski, J.
Szymańska, A.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/331930.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
Propagation of ultrasonic waves in the tissue is sensitive to the alternation of tissue composition and structure.. This paper presents the classification of healthy skin and skin lesions (basal cell carcinoma (BCC)) based on statistic parameters of the envelope of echosignal. The statistics of envelope of the ultrasonic signal was modeled using Rayleigh and non-Rayleigh (the K-distribution) statistics. Furthermore the characteristic parameter of K-distribution, the effective number of scaterrers (M) was investigated. Comparison of the results obtained for region of the skin where the BCC was diagnosed and the regions of healthy skin has shown differences in the values of M parameter. These results indicate that this parameter has the potential for extracting information useful for characterizing skin lesions.
Źródło:
Hydroacoustics; 2012, 15; 171-178
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultrasonic Echosignal Applied to Human Skin Lesions Characterization
Autorzy:
Piotrzkowska, H.
Litniewski, J.
Szymańska, E.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/177296.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
statistics
K-distribution
Rayleigh distribution
ultrasonic scattering
human dermis
Opis:
The paper presents a classification of the healthy skin and the skin lesions (basal cell carcinoma) basing on a statistics of the envelope of ultrasonic echoes. The echoes envelopes distributions were modeled using Rayleigh and K-distribution. The distributions were compared with empirical data to find which of them better models the statistics of the echo-signal obtained from the human skin. The results indicated that the K-distribution provides a better fit. Also, a characteristic parameter of the K-distribution, the effective number of scatterers (M), was investigated. The values of the M parameter, obtained for the skin cancer (basal cell carcinoma), were lower as compared to those obtained for the healthy skin. The results indicate that the statistical quan- titative ultrasound parameters have a potential for extracting information useful for characterization of the skin condition.
Źródło:
Archives of Acoustics; 2012, 37, 1; 103-108
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial and Frequency Compounding in Application to Attenuation Estimation in Tissue
Autorzy:
Klimonda, Z.
Litniewski, J.
Karwat, P.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/177604.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
tissue attenuation estimation
parametric imaging
synthetic aperture
spatial compounding
frequency compounding
Opis:
The soft tissue attenuation is an interesting parameter from medical point of view, because the value of attenuation coefficient is often related to the state of the tissue. Thus, the imaging of the attenuation coefficient distribution within the tissue could be a useful tool for ultrasonic medical diagnosis. The method of attenuation estimation based on tracking of the mean frequency changes in a backscattered signal is presented in this paper. The attenuation estimates are characterized by high variance due to stochastic character of the backscattered ultrasonic signal and some special methods must be added to data processing to improve the resulting images. The following paper presents the application of Spatial Compounding (SC), Frequency Compounding (FC) and the combination of both. The resulting parametric images are compared by means of root-mean-square errors. The results show that combined SC and FC techniques significantly improve the quality and accuracy of parametric images of attenuation distribution.
Źródło:
Archives of Acoustics; 2014, 39, 4; 519-527
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of the transducer bandwidth and double pulse transmission on the encoded imaging ultrasound
Autorzy:
Trots, I.
Nowicki, A.
Lewandowski, M.
Secomski, W.
Litniewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/331651.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
encoded imaging ultrasound
ultrasound imaging transducer
CGS
Opis:
An influence effect of fractional bandwidth of ultrasound imaging transducer on the gain of compressed echo signal being the complementary Golay sequences (CGS) with different spectral widths is studied in this paper. Also, a new composing transmission method of CGS is discussed together with compression technique applied in order to increase the signal-to-noise ratio (SNR) and penetration. The CGS with two different bit lengths, one-cycle and two-cycles are investigated. Two transducers with fractional bandwidth of 25% and 80% at centre frequency 6 MHz are used. The experimental results are presented, clearly proofing that increasing of the code length leads to compressed echo amplitude enhancement. The smaller the bandwidth is the larger is this effect; the pulse-echo sensitivity of the echo amplitude increases by 1.88 for 25% fractional bandwidth and 1.47 for 80% while preserving time resolution. The presented results of double transmission of short codes show the penetration and SNR improvement while maintaining dead zone.
Źródło:
Hydroacoustics; 2008, 11; 419-430
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Statistics of envelope of high frequency ultrasound signal backscattered in human dermis
Autorzy:
Piotrzkowska, H.
Litniewski, J.
Szymańska, E.
Lewandowski, M.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/331987.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Akustyczne
Opis:
The scattering of ultrasonic waves depends on the size, shape, acoustical properties and concentration of scatterers in tissue. In these study K distribution of the ultrasound backscatter envelope was used to assess the structural properties of the skin tissue. The custom-designed high frequency ultrasonic scanner was applied to obtain RF B-scans of the skin in vivo at the frequency of 20 ÷ 30MHz. The results are encouraging. The K distribution models the envelope statistics very well. The parameters of the K-distribution, namely, the effective number of scatterers may be useful for the skin characterization.
Źródło:
Hydroacoustics; 2010, 13; 205-214
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 16

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