prof. dr hab. Jerzy Litniewski 

Doktorat
1990  Sygnał z mikroskopu akustycznego przy pracy poza ogniskiem i jego zastosowanie do interpretacji obrazów biologicznych
 463 
Habilitacja
Profesura
20150217  Nadanie tytułu naukowego profesora 
Promotor prac doktorskich
1.  20130524  Klimonda Ziemowit  Obrazowanie parametryczne tłumienia fali ultradźwiękowej w tkance miękkiej  659  
2.  20130524  PiotrzkowskaWróblewska Hanna  Wyznaczanie parametrów skóry ludzkiej in vivo za pomocą ultradźwięków wysokiej częstotliwości  660 
Ostatnie publikacje
1.  Klimonda Z., Postema M., Nowicki A., Litniewski J., Tissue Attenuation Estimation by Mean Frequency Downshift and Bandwidth Limitation, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, ISSN: 08853010, DOI: 10.1109/TUFFC.2016.2574399, Vol.63, No.8, pp.11071115, 2016 Streszczenie: Attenuation of ultrasound in tissue can be estimated from the propagating pulse center frequency downshift. This method assumes that the envelope of the emitted pulse can be approximated by a Gaussian function and that the attenuation linearly depends on frequency. The resulting downshift of the mean frequency depends not only on attenuation but also on pulse bandwidth and propagation distance. This kind of approach is valid for narrowband pulses and shallow penetration depth. However, for short pulses and deep penetration, the frequency downshift is rather large and the received spectra are modified by the limited bandwidth of the receiving system. In this paper, the modified formula modeling the mean frequency of backscattered echoes is presented. The equation takes into account the limitation of the bandwidth due to bandpass filtration of the received echoes. This approach was applied to simulate the variation of the mean frequency of the pulse propagating for both weakly and strongly attenuating media and for narrowband and wideband pulses. The behavior of both the standard and modified estimates of attenuation has been validated using RF data from a tissuemimicking phantom. The ultrasound attenuation of the phantom, determined with a corrected equation, was close to its true value, while the result obtained using the original formula was lower by as much as 50% at a depth of 8 cm. Słowa kluczowe: Tissue attenuation, frequency downshift, bandwidth limitation Afiliacje autorów:
 30p.  
2.  Karwat P., Kujawska T., Lewin P.A.^{♦}, Secomski W., Gambin B., Litniewski J., Determining temperature distribution in tissue in the focal plane of the high (>100 W/cm2) intensity focused ultrasound beam using phase shift of ultrasound echoes, Ultrasonics, ISSN: 0041624X, DOI: 10.1016/j.ultras.2015.10.002, Vol.65, pp.211219, 2016 Streszczenie: In therapeutic applications of High Intensity Focused Ultrasound (HIFU) the guidance of the HIFU beam and especially its focal plane is of crucial importance. This guidance is needed to appropriately target the focal plane and hence the whole focal volume inside the tumor tissue prior to thermoablative treatment and beginning of tissue necrosis. This is currently done using Magnetic Resonance Imaging that is relatively expensive. In this study an ultrasound method, which calculates the variations of speed of sound in the locally heated tissue volume by analyzing the phase shifts of echosignals received by an ultrasound scanner from this very volume is presented. To improve spatial resolution of Bmode imaging and minimize the uncertainty of temperature estimation the acoustic signals were transmitted and received by 8 MHz linear phased array employing Synthetic Transmit Aperture (STA) technique. Initially, the validity of the algorithm developed was verified experimentally in a tissuemimicking phantom heated from 20.6 to 48.6°C. Subsequently, the method was tested using a pork loin sample heated locally by a 2 MHz pulsed HIFU beam with focal intensity ISATA of 129 W/cm2. The temperature calibration of 2D maps of changes in the sound velocity induced by heating was performed by comparison of the algorithmdetermined changes in the sound velocity with the temperatures measured by thermocouples located in the heated tissue volume. The method developed enabled ultrasound temperature imaging of the heated tissue volume from the very inception of heating with the contrasttonoise ratio of 3.5–12 dB in the temperature range 21–56°C. Concurrently performed, conventional Bmode imaging revealed CNR close to zero dB until the temperature reached 50°C causing necrosis. The data presented suggest that the proposed method could offer an alternative to MRIguided temperature imaging for prediction of the location and extent of the thermal lesion prior to applying the final HIFU treatment. Słowa kluczowe: Ultrasonic temperature imaging, HIFU, Echo phase shift, Velocity image contrast Afiliacje autorów:
 30p.  
3.  Tasinkevych Y., Podhajecki J., Falińska K., Litniewski J., Simultaneous estimation of cortical bone thickness and acoustic wave velocity using a multivariable optimization approach: Bone phantom and invitro study, Ultrasonics, ISSN: 0041624X, DOI: 10.1016/j.ultras.2015.10.013, Vol.65, pp.105112, 2016 Streszczenie: The paper presents a method that allows the thickness of a compact bone layer and longitudinal wave velocity in the bone to be determined simultaneously with the use of reflected waves, with particular emphasis on the case of layers when the propagation time through the layer is shorter than the time duration of the interrogating pulse. Słowa kluczowe: Bone quantitative ultrasound, Human cortical bone, Human cancellous bone, Ultrasound attenuation, Layered media Afiliacje autorów:
 30p.  
4.  PiotrzkowskaWroblewska H., DobruchSobczak K., Litniewski J., Chrapowicki E.^{♦}, RoszkowskaPurska K.^{♦}, Nowicki A., Differentiation of the breast lesions using statistics of backscattered echoes, HYDROACOUSTICS, ISSN: 16421817, Vol.19, pp.319328, 2016 Streszczenie: The purpose of this study was to evaluate the accuracy of statistical properties of the backscttered ultrasound in differential diagnosis of the breast lesions. The Bmode images together with the appropriate RF echoes from the breast lesions and surrounding tissues were collected. The RF data were processed for the statistics of the backscattered echo signals using K and Nakagami distributions characterized by the M and m parameters, respectively. Based on both, M and m parameters, a set of 18 parameters was derived. Słowa kluczowe: quantitative ultrasound, breast cancer, Nakagami distribution, K dstribution Afiliacje autorów:
 6p.  
5.  Karwat P., Kujawska T., Secomski W., Gambin B., Litniewski J., Application of ultrasound to noninvasive imaging of temperature distribution induced in tissue, HYDROACOUSTICS, ISSN: 16421817, Vol.19, pp.219228, 2016 Streszczenie: 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 thermoablative 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 echosignals 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. Słowa kluczowe: HIFU, echo phase shift, parametric imaging, velocity/brightness CNR Afiliacje autorów:
 6p.  
6.  Piotrzkowska H., Litniewski J., Szymańska E.^{♦}, Nowicki A., Quantitative sonography of basal cell carcinoma, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 03015629, DOI: 10.1016/j.ultrasmedbio.2014.11.016, Vol.41, No.3, pp.748759, 2015 Streszczenie: A 30MHz ultrasonic scanner was used to collect Bscan images together with appropriate radiofrequency echoes from diseased and healthy skin regions of patients with diagnosed basal cell carcinoma and precancerous lesions (actinic keratosis). Radiofrequency data were processed to obtain the attenuation coefficient and statistics of the backscattered echo signal determination (Kdistribution and effective density of scatterers [EDS]). The attenuation coefficient was significantly higher for patients with basal cell carcinoma than for healthy patients. Also, the precancerous skin lesions had increased attenuation. The averaged EDS values for cancer lesions were significantly lower than those for precancerous lesions and healthy skin. The successful differentiation between the tissue groups examined suggests the potential value of the attenuation coefficient and EDS for carcinoma characterization. Słowa kluczowe: Quantitative ultrasound, High frequency, Human skin, Skin lesions, Kdistribution, Attenuation coefficient, Tissue characterization Afiliacje autorów:
 35p.  
7.  Maj M.^{♦}, WarszawikHendzel O.^{♦}, Szymańska E.^{♦}, Walecka I.^{♦}, Rakowska A.^{♦}, AntczakMarczak M.^{♦}, Kuna P.^{♦}, Kruszewski J.^{♦}, NasierowskaGuttmejer A.^{♦}, Litniewski J., Nowicki A., Olszewska M.^{♦}, Rudnicka L.^{♦}, High frequency ultrasonography: a complementary diagnostic method in evaluation of primary cutaneous melanoma, GIORNALE ITALIANO DI DERMATOLOGIA E VENEREOLOGIA, ISSN: 03920488, Vol.150, No.5, pp.595601, 2015 Streszczenie: Aim. Słowa kluczowe: Dermoscopy  Diagnosis  Melanoma  Microscopy, confocal  Ultrasonography Afiliacje autorów:
 15p.  
8.  Wójcik J., Gambin B., Litniewski J., Theoretical results and numerical study on the nonlinear reflection and transmission of plane sound waves, HYDROACOUSTICS, ISSN: 16421817, Vol.18, pp.181192, 2015 Streszczenie: 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 Słowa kluczowe: Nonliear reflection, transmission, Riccati equation Afiliacje autorów:
 6p.  
9.  Tasinkevych Y., Podhajecki J., Wójcik J., Falińska K., Litniewski J., Estimation of layer thickness by the cost function optimization: phantom study, HYDROACOUSTICS, ISSN: 16421817, Vol.18, pp.161166, 2015 Streszczenie: The aim of this work is to present preliminary results of the layer thickness assessment method based on optimization approach. The developed method is based on a multilayer model structure. The measured acoustic signal reflected from the layer is compared with a simulated signal on the basis of a multilayer model. The cost function is defined as the difference between the reflected signal measured using pulse echo approach and the simulated signal. The thickness of the solid layer is the parameter which minimizes the cost function yielding desired solution. Minimization of the cost function is performed with the simulated annealing algorithm. The results obtained with the developed method using measurement data of a custom design model are compared with the reference value and the accuracy of the method is checked. The relative error of the thickness estimation is 1.44 %. Słowa kluczowe: Bone quantitative ultrasound, Human cortical bone, Human cancellous bone, Ultrasound attenuation, Layered media Afiliacje autorów:
 6p.  
10.  Karwat P., Litniewski J., Kujawska T., Secomski W., Krawczyk K., Noninvasive Imaging of Thermal Fields Induced in Soft Tissues In Vitro by Pulsed Focused Ultrasound Using Analysis of Echoes Displacement, ARCHIVES OF ACOUSTICS, ISSN: 01375075, DOI: 10.2478/aoa20140014, Vol.39, No.1, pp.139144, 2014 Streszczenie: Therapeutic and surgical applications of focused ultrasound require monitoring of local temperature rises induced inside tissues. From an economic and practical point of view ultrasonic imaging techniques seem to be the most suitable for the temperature control. This paper presents an implementation of the ultrasonic echoes displacement estimation technique for monitoring of local temperature rise in tissue during its heating by focused ultrasound The results of the estimation were compared to the temperature measured with thermocouple. The obtained results enable to evaluate the temperature fields induced in tissues by pulsed focused ultrasonic beams using noninvasive imaging ultrasound technique Słowa kluczowe: HIFU, therapeutic ultrasound, ultrasonic imaging, echo strain estimation Afiliacje autorów:
 15p.  
11.  Klimonda Z., Litniewski J., Karwat P., Nowicki A., Spatial and Frequency Compounding in Application to Attenuation Estimation in Tissue, ARCHIVES OF ACOUSTICS, ISSN: 01375075, DOI: 10.2478/aoa20140056, Vol.39, No.4, pp.519527, 2014 Streszczenie: 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 rootmeansquare errors. The results show that combined SC and FC techniques significantly improve the quality and accuracy of parametric images of attenuation distribution. Słowa kluczowe: tissue attenuation estimation, parametric imaging, synthetic aperture, spatial compounding, frequency compounding Afiliacje autorów:
 15p.  
12.  Falińska K., Litniewski J., Tasinkevych Y., Assesment of cortical bone thickness using cepstrum analysis. Simulation study, HYDROACOUSTICS, ISSN: 16421817, Vol.17, pp.4756, 2014 Streszczenie: Assessment of cortical bone thickness is important from a medical point of view because bonelayer thickness has a diagnostic value. The thinning of the cortical bone layer reduces the mechanical strength of the bone and exposes it to an increased risk of osteoporotic fractures [1]. The hip bone (proximal femur) is the most critical fracture site. The thickness of the cortical layer in the proximal femur is often too thin to be detected from ultrasonic echoes using traditional peak detection methods (for example the envelope method). In such a case the cepstrum analysis technique may be very useful. In this study the cepstrum method was applied to analyze numerically simulated echoes reflected from the layer and to determine layer thickness. In simulation, the transducer operated at 1 MHz and pulses of a 1.5 microsec. duration were assumed. Słowa kluczowe: cortical bone, thickness, cepstrum analysis Afiliacje autorów:
 7p.  
13.  Nowicki A., Byra M., Litniewski J., Wójcik J., Ultrasound imaging of stiffness with two frequency pulse, HYDROACOUSTICS, ISSN: 16421817, Vol.17, pp.151160, 2014 Streszczenie: 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 bandpass 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. Afiliacje autorów:
 7p.  
14.  Węglewski W., Bochenek K., Basista M., Schubert Th.^{♦}, Jehring U.^{♦}, Litniewski J., Mackiewicz S., Comparative assessment of Young’s modulus measurements of metalceramic composites using mechanical and nondestructive tests and microCT based computational modeling, COMPUTATIONAL MATERIALS SCIENCE, ISSN: 09270256, DOI: 10.1016/j.commatsci.2013.04.007, Vol.77, pp.1930, 2013 Streszczenie: It is commonly known that the available nondestructive and mechanical methods of the Young modulus measurement yield different results. This paper presents comparison of the results of experimental determination and numerical modeling of the Young modulus of Cr–Al2O3–Re composites (MMC) processed by a powder metallurgical method (SPS). In the computational model a finite element analysis is combined with images of the real material microstructure obtained from microcomputed tomography (microCT). Experimental measurements were carried out by four testing methods: threepoint bending, resonance frequency damping analysis (RFDA), ultrasonic pulseecho technique, and scanning acoustic microscopy. The paper also addresses the issue which of the four experimental methods at hand gives results closest to the theoretical predictions of the microCT based FEM model. Słowa kluczowe: Finite element analysis (FEA), MicroCT based FE model, Metal matrix composites, Elastic modulus, Mechanical and nondestructive techniques Afiliacje autorów:
 30p.  
15.  Litniewski J., Cieślik L., Lewandowski M., Tymkiewicz R., Zienkiewicz B., Nowicki A., Ultrasonic Scanner for In Vivo Measurement of Cancellous Bone Properties From Backscattered Data, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, ISSN: 08853010, DOI: 10.1109/TUFFC.2012.2347, Vol.59, No.7, pp.14701477, 2012 Streszczenie: A dedicated ultrasonic scanner for acquiring RF echoes backscattered from the trabecular bone was developed. The design of device is based on the goal of minimizing of custom electronics and computations executed solely on the main computer processor and the graphics card. The electronic encoderdigitizer module executing all of the transmission and reception functions is based on a single lowcost field programmable gate array (FPGA). The scanner is equipped with a mechanical sectorscan probe with a concave transducer with 50 mm focal length, center frequency of 1.5 MHz and 60% bandwidth at −6 dB. The example of femoral neck bone examination shows that the scanner can provide ultrasonic data from deeply located bones with the ultrasound penetrating the trabecular bone up to a depth of 20 mm. It is also shown that the RF echo data acquired with the scanner allow for the estimation of attenuation coefficient and frequency dependence of backscattering coefficient of trabecular bone. The values of the calculated parameters are in the range of corresponding in vitro data from the literature but their variation is relatively high. Słowa kluczowe: cancellous bone, broadband ultrasound attenuation, FPGA Afiliacje autorów:
 35p.  
16.  Piotrzkowska H., Litniewski J., Szymańska E.^{♦}, Nowicki A., Ultrasonic Echosignal Applied to Human Skin Lesions Characterization, ARCHIVES OF ACOUSTICS, ISSN: 01375075, Vol.37, No.1, pp.103108, 2012 Streszczenie: 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 Kdistribution. The distributions were compared with empirical data to ﬁnd which of them better models the statistics of the echosignal obtained from the human skin. The results indicated that the Kdistribution provides a better ﬁt. Also, a characteristic parameter of the Kdistribution, 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 quantitative ultrasound parameters have a potential for extracting information useful for characterization of the skin condition. Słowa kluczowe: statistics, Kdistribution, Rayleigh distribution, ultrasonic scattering, human dermis Afiliacje autorów:
 15p.  
17.  Piotrzkowska H., Litniewski J., Szymańska E.^{♦}, Nowicki A., Statistical Analysis of Ultrasound Echo for Skin Lesions Classification, HYDROACOUSTICS, ISSN: 16421817, Vol.15, pp.171178, 2012 Streszczenie: 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 nonRayleigh (the Kdistribution) statistics. Furthermore the characteristic parameter of Kdistribution, the effective number of scaterrers (M) was investigated. Słowa kluczowe: high frequency, ultrasound, basall cell carcinoma, ststistics Afiliacje autorów:
 4p.  
18.  Litniewski J., Klimonda Z., Nowicki A., Parametric Sonographic Imaging – Application of Synthetic Aperture Technique to Imaging Attenuation of Ultrasound in Tissue Structures, HYDROACOUSTICS, ISSN: 16421817, Vol.15, pp.99110, 2012 Streszczenie: Ultrasonic imaging is a wellestablished 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. Słowa kluczowe: soft tissue parametric imaging, attenuation imaging, synthetic aperture focusing technique Afiliacje autorów:
 4p.  
19.  Wójcik J., Litniewski J., Nowicki A., Modeling and analysis of multiple scattering of acoustic waves in complex media: Application to the trabecular bone, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, ISSN: 00014966, Vol.130, No.4, pp.19081918, 2011 Streszczenie: The integral equations that describe scattering in the media with steprise changing parameters have been numerically solved for the trabecular bone model. The model consists of several hundred discrete randomly distributed elements. The spectral distribution of scattering coefficients in subse quent orders of scattering has been presented. Calculations were carried on for the ultrasonic frequency ranging from 0.5 to 3 MHz. Evaluation of the contribution of the first, second, and higher scattering orders to total scattering of the ultrasounds in trabecular bone was done. Contrary to the approaches that use the lCT images of trabecular structure to modeling of the ultrasonic wave propagation condition, the 3D numerical model consisting of cylindrical elements mimicking the spatial matrix of trabeculae, was applied. The scattering, due to interconnections between thick trabeculae, usually neglected in trabecular bone models, has been included in calculations when the structure backscatter was evaluated. Influence of the absorption in subsequent orders of scattering is also addressed. Results show that up to 1.5 MHz, the influence of higher scattering orders on the total scattered field characteristic can be neglected while for the higher frequencies, the relatively high amplitude interference peaks in higher scattering orders clearly occur. Słowa kluczowe: Multiple scattering, Complex media, Bone Afiliacje autorów:
 35p.  
20.  Litniewski J., Cieślik L., Wójcik J., Nowicki A., Statistics of the envelope of ultrasonic backscatter from human trabecular bone, JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA, ISSN: 00014966, Vol.130, No.4, pp.22242232, 2011 Streszczenie: The paper describes the investigations intended to compare the results of experimental measurements f backscattering properties of the trabecular bone with the results of computer simulations. Ultrasonic RF echoes were collected using two bone scanners operating at 0.58 and 1.3 MHz. The simulations of the backscattered RF echoes were performed using the scattering model of the trabecular bone that consisted of cylindrical and spherical elements uniformly distributed in waterlike medium. For each measured or simulated RF backscatter the statistical properties of the signal envelope were determined. Experimental results suggest deviations of the backscattering properties from the Rayleigh distribution. The results of simulation suggest that deviation from Rayleigh distribution depends on the variation of trabeculae diameters and the number of thin trabeculae. Experimentally determined deviations corresponded well to the deviations calculated from simulated echoes assuming trabeculae thickness variation equaled to the earlier published histomorphometric study results. Słowa kluczowe: trabecular bone, scattering statistics, bone model Afiliacje autorów:
 35p.  
21.  Klimonda Z., Litniewski J., Nowicki A., Synthetic Aperture Technique Applied to Tissue Attenuation Imaging, ARCHIVES OF ACOUSTICS, ISSN: 01375075, Vol.36, No.4, pp.927935, 2011 Streszczenie: The attenuating properties of biological tissue are of great importance in ultrasonic medical imaging. Investigations performed in vitro and in vivo showed the correlation 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 meanfrequency 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) transmitreceiving 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. Słowa kluczowe: tissue attenuation imaging, synthetic aperture, diagnosis enhancing Afiliacje autorów:
 15p.  
22.  Szymańska E.^{♦}, Maj M.^{♦}, Majsterek M.^{♦}, Litniewski J., Nowicki A., Rudnicka L.^{♦}, Zastosowanie ultrasonografii wysokiej częstotliwości w diagnostyce dermatologicznej – obraz ultrasonograficzny wybranych zmian skórnych, POLSKI MERKURIUSZ LEKARSKI, ISSN: 14269686, Vol.31, No.181, pp.3740, 2011 Streszczenie: Typical diagnostic process in dermatology includes clinical assessment, dermoscopic and histopathologic examination. Microsonography was initiated in seventies and much progress in the development of highfrequency scanners occurred since that time. The aim of the study was the assessment of high frequency ultrasonography in dermatologic diagnostics. Material and methods. Examination was performed with 30 MHz ultrasound transducer with 0,1 mm resolution and 7 mm penetration. We examined patients with benign and malignant neoplasms, cicatrical alopecia and morphea. Results. Sonographically, the normal skin is composed of three layers: an epidermal entry echo, dermis and subcutaneous tissue. In healthy skin we can image small hypoechoic areas which correspond to hair folicules, vessels and sebaceous glands. Most of small skin neoplasmatic lesions were hypoechogenic and homogeneous on examination. Extensive lesions were multicomponent with normo, hypo and anechogenic structures. The assessment of lesion’s boarders allows sometimes to conclude the invasiveness of the lesion. Areas of skin with clinically visible atrophy showed diffuse increasing of echogenicity. In early lesions, without accomplished fibrosis, diffuse decreasing of echogenicity can be observed, that is probably caused by inflammatory infiltration. In comparison to the healthy skin, the ultrasound scan of sclerotic skin shows a wide entry echo and highly reflective, thicker dermis as a result of the collagen fibers accumulation. Conclusions. Above data suggest that ultrasonographic examination may be a valuable dermatologic diagnostic tool that completes classical dermatologic diagnostics and helps to plan the treatment. Słowa kluczowe: high frequency ultrasonography, benign neoplasms, malignant neoplasms, cicatrical alopecia, morphea Afiliacje autorów:
 7p.  
23.  Wójcik J., Litniewski J., Nowicki A., Gambin B., Applying crystallography in analysis of trabecular bone backscatter, HYDROACOUSTICS, ISSN: 16421817, Vol.14, pp.255266, 2011 Streszczenie: Some important details of the Backscatter Effective CrossSections (BECS) 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. Słowa kluczowe: Multi scattering, Random structures Afiliacje autorów:
 4p.  
24.  Litniewski J., Klimonda Z., Nowicki A., The Synthetic Aperture technique for tissue attenuation imaging, Annual Report  Polish Academy of Sciences, ISSN: 16403754, pp.6567, 2011 Streszczenie: The mean frequency correlation estimator and SSA technique were implemented for processing of the RF ultrasonic echoes. The estimated attenuation values were equal to 0.7 and 0.9 dB/(MHz∙cm) and agreed well with the real values. We have found the RF data obtained using synthetic aperture technique (SA) to be much more reliable in terms of attenuation extraction then echoes recorded using the standard delay and sum (DAS) beamforming. The imaging of attenuation in tissue seems to be a promising technique in medical diagnostics, although the precision of a single scan is often unsatisfactory. Słowa kluczowe: tissue attenuation imaging, sythetic aperture focusing technique Afiliacje autorów:
 
25.  Litniewski J., Statistics of Envelope of HighFrequency Ultrasonic Backscatter from Trabecular Bone: Simulation Study, ARCHIVES OF ACOUSTICS, ISSN: 01375075, Vol.35, No.3, pp.349360, 2010 Streszczenie: The paper considers the application of statistical properties of backscattered ultrasonic signal for assessment of the trabecular bone status. Computer simulations were conducted to investigate the properties of the ultrasound pulseecho signal, as it is received on the transducer surface after scattering in trabecular bone. The microarchitecture of trabecular bone was modeled by a random distribution of long and thin cylindrical scatterers of randomly varying diameters and mechanical properties, oriented perpendicular to the ultrasound beam axis. The received echo signal was calculated as a superposition of echoes from all the scatterers present in the scattering volume. The simulated signal envelope was used for statistical processing to compute various parameters like the mean amplitude, the amplitude MSR defined as the ratio of the mean to the standard deviation and the amplitude histogram. Results indicated that while for the welldefined trabeculae properties within the simulated bone structure the signal envelope values are Rayleigh distributed the significant departures from Rayleigh statistics may be expected as the thickness of trabeculae become random. The influence of the variation of mechanical properties of the bone tissue building the trabeculae on the bone backscattered signal parameters was not observed. Słowa kluczowe: trabecular bone, Rayleigh distribution, scattering, simulations Afiliacje autorów:
 9p.  
26.  Wójcik J., Litniewski J., Nowicki A., Example of structure modeling and analysis of ultrasound scattering for trabecular bone, ARCHIVES OF ACOUSTICS, ISSN: 01375075, Vol.35, No.4, pp.701713, 2010 Streszczenie: 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 finitelength 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 SturmLiouville equation describing a scalar wave in inhomogeneous and lossy media. For the scattered fields calculated numerically the effective crosssections 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 crosssection 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. Słowa kluczowe: multiscattering, random complex structures, trabecular bone model Afiliacje autorów:
 9p.  
27.  Klimonda Z., Litniewski J., Nowicki A., Tissue attenuation estimation from backscattered ultrasound using spatial compounding technique – preliminary results, ARCHIVES OF ACOUSTICS, ISSN: 01375075, Vol.35, No.4, pp.643652, 2010 Streszczenie: 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 develop ing 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 atten uation 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. Słowa kluczowe: ultrasound attenuation estimation, spatial compounding, parametric imaging Afiliacje autorów:
 9p.  
28.  Piotrzkowska H., Litniewski J., Szymańska E.^{♦}, Lewandowski M., Nowicki A., Statistics of envelope of high frequency ultrasound signal backscattered in human dermis, HYDROACOUSTICS, ISSN: 16421817, Vol.13, pp.205214, 2010 Streszczenie: 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 customdesigned high frequency ultrasonic scanner was applied to obtain RF Bscans of the skin in vivo at the frequency of 2030MHz. Słowa kluczowe: skin characterization, ultrasound, K distribution Afiliacje autorów:
 6p.  
29.  Klimonda Z., Litniewski J., Nowicki A., Preliminary results of attenuation estimation from tissue backscatter using commercial ultrasonic scanner, HYDROACOUSTICS, ISSN: 16421817, Vol.13, pp.127134, 2010 Streszczenie: 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. Słowa kluczowe: tissue attenuation imaging, ultrasound attenuation estimation Afiliacje autorów:
 6p.  
30.  Cieślik L., Litniewski J., Lewandowski M., Nowicki A., Evaluation of trabecular bone properties using ultrasonic scanner, HYDROACOUSTICS, ISSN: 16421817, Vol.13, pp.3952, 2010 Streszczenie: 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. Słowa kluczowe: bone structure, bone properties, calcaneus Afiliacje autorów:
 6p.  
31.  Litniewski J., Nowicki A., Wójcik J., Ultrasonic characterization of trabecular bone: Two scatterers’ population model, Physics Procedia, ISSN: 18753892, DOI: 10.1016/j.phpro.2010.01.089, Vol.3, pp.707712, 2010 Streszczenie: The paper describes the computer simulations allowing investigating the properties of the ultrasound pulseecho signal, as it is received on the transducer surface after scattering in trabecular bone. A novel computer simulation model provides better understanding of ultrasonic scattering in porous bone structure and it can be also used to yield an ideal environment in which, the effects of various parameters (scatterer mechanical and geometrical properties, scatterer’ concentration), the shape of incident wave and experimental conditions influencing the scattering of ultrasonic waves in trabecular bone structure can be examined individually. The results proved that the computer simulation has a particular relevance in studying scattering in cancellous bone which may be approximated as a collection of two populations of scatterers, cylindrical and spherical that imitate thick and thin trabeculae respectively. Słowa kluczowe: bone modeling, scattering simulation, osteoporosis, trabecular bone Afiliacje autorów:
 
32.  Litniewski J., Nowicki A., Lewin P.A.^{♦}, Semiempirical bone model for determination of trabecular structure properties from backscattered ultrasound, Ultrasonics, ISSN: 0041624X, Vol.49, pp.505513, 2009  27p.  
33.  Klimonda Z., Litniewski J., Nowicki A., Spatial resolution of attenuation imaging, ARCHIVES OF ACOUSTICS, ISSN: 01375075, Vol.34, No.4, pp.461470, 2009 Streszczenie: The attenuating properties of biological tissue are of great importance in ultrasonic examination even though its anatomical variability limits diagnostics effectiveness. We are currently developing a technique for parametric imaging of attenuation and we intend to apply it for in vivo characterization of tissue. The diagnostic usefulness of the proposed technique crucially depends on the precision of the attenuation estimate and the resolution of the parametric image. These two parameters are highly correlated, since the resolution is reduced whenever averaging is used to minimize the errors introduced by the random character of the backscatter. Here we report on the results of numerical processing of both, simulated and recorded from a tissuemimicking phantom echoes. We have analyzed the parameters of the estimation technique and examined their influence on the precision of the attenuation estimate and on the parametric image resolution. The optimal selection of attenuation image parameters depending on its intended diagnostic use, was also considered. Słowa kluczowe: ultrasound attenuation, spatial resolution, parametric imaging Afiliacje autorów:
 9p.  
34.  Piotrzkowska H., Litniewski J., Lewandowski M., Szymańska E.^{♦}, Nowicki A., Use of quantitative ultrasound to measure acoustic properties of human skin, ARCHIVES OF ACOUSTICS, ISSN: 01375075, Vol.34, No.4, pp.471480, 2009 Streszczenie: The scattering of ultrasonic waves depends on the size, shape, acoustical properties and concentration of scatterers in the tissue. The spectrum of the ultrasonic backscatter can be used to characterize noninvasively the structural and mechanical properties of tissue. We intend to apply the customdesigned highfrequency ultrasonic scanner for the skin and cutaneous lesions characterization by evaluating their attenuating and scattering properties. In this pilot study, we have explored the possibility of extracting the human skin backscattering coeﬃcient (BC) from the ultrasonic Bscans obtained in vivo at 20–30 MHz. The measured BC values of normal skin (dermis) agree well with the published data. We have found also that the spatial resolution of the BC determination using our scanner is suﬃcient (aprox. 1 mm2) to characterize small skin lesions and assess their penetration depth. Słowa kluczowe: attenuation coefficient, backscattering coefficient, dermis Afiliacje autorów:
 9p.  
35.  Wójcik J., Litniewski J., Nowicki A., Multiple scattering contribution to trabecular bone backscatter, HYDROACOUSTICS, ISSN: 16421817, Vol.12, pp.227236, 2009 Streszczenie: Integral equations that describe scattering on the structure with step like abruptly changing physical 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  first second and third of scattering has been presented. Słowa kluczowe: Multiple scattering in absorbing medium, Complex random structure, Back scatter coefficients Afiliacje autorów:
 6p.  
36.  Dynowski K.^{♦}, Litniewski J., Nowicki A., Scanning acoustic microscope for 3D imaging, ARCHIVES OF ACOUSTICS, ISSN: 01375075, Vol.33, No.3, pp.293302, 2008 Streszczenie: A new Acoustic Microscope operating at the frequency up to 200 MHz and allowing for visualization of the internal structures of materials was developed. The system was built basing on the commercially available components and the selfdesigned acoustic lenses. The dedicated software was developed to control the process of 3D RFdata acquisition, processing and presenting in 2D crosssections or 3D surface rendering mode. This article describes the technical principles of the constructed microscope and presents the reconstructed images of the designed testprobe and of the integrated circuit. Słowa kluczowe: Acoustic Microscopy, SAM, 3D imaging, rendering, subsurface imaging Afiliacje autorów:
 
37.  Trots I., Nowicki A., Lewandowski M., Secomski W., Litniewski J., Double pulse transmission  signal to noise ratio improvement in ultrasound imaging, ARCHIVES OF ACOUSTICS, ISSN: 01375075, Vol.33, No.4, pp.593601, 2008 Streszczenie: This study investigates a new composing method of double transmission of short coded sequences based on wellknown Golay complementary codes, which allow to obtain the higher signaltonoise ratio (SNR) and increase penetration depth. The proposed method can potentially find application in small parts ultrasonography and play important role in examination of superficial structures, e.g. in dermatology, ophthalmology, etc., where using longer coded sequences leads to increase of a dead zone and single pulse transmission of short sequences does not assure sufficient SNR. This paper discusses the comparison of results obtained during the examination of four different lengths pairs of Golay coded sequences excited at 3.7 MHz: the single 64bits pair of Golay sequences and combined sequences consisting of two 8, 16, and 32bits Golay codes separated in time. The experimental results have shown that using the double pulse transmission allows to suppress considerably the noise level, the SNR increases by 5.7 dB in comparison with the single pulse transmission of Golay sequences of the same length. The results of this work indicate that double pulse transmission enhances SNR while maintaining the dead zone short. Słowa kluczowe: Golay complementary sequences, double pulse transmission, dead zone Afiliacje autorów:
 
38.  Litniewski J., Statistical properties of pulseecho signal backscattered in trabecular bone, HYDROACOUSTICS, ISSN: 16421817, Vol.11, pp.253264, 2008  
39.  Trots I., Nowicki A., Lewandowski M., Secomski W., Litniewski J., The influence of the transducer bandwidth and double pulse transmission on the encoded imaging ultrasound, HYDROACOUSTICS, ISSN: 16421817, Vol.11, pp.419430, 2008 Streszczenie: 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 signaltonoise ratio (SNR) and penetration. Słowa kluczowe: ultrasound, transducer, bandwidth, Golay code Afiliacje autorów:
 
40.  Litniewski J., Nowicki A., Klimonda Z., Lewandowski M., Sound fields for coded excitations in water and tissue, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 03015629, Vol.33, No.4, pp.601607, 2007 Streszczenie: Coded ultrasonography is intensively studied in many laboratories due to its remarkable properties, particularly increased penetration depth and signaltonoise ratio (SNR). However, no data on the spatial behavior of the pressure field generated by coded bursts transmissions in the tissue were yet reported. This paper reports the results of investigations of the field structure in water, in degassed beef liver and in pork tissue using four different excitations signals, two and 16 periods sine bursts and sinusoidal sequences with phase modulation using 13bits Barker code and 16bits Golay complementary codes. The results of measured pressure field distributions before and after compression were compared with those recorded using short pulse excitation. Słowa kluczowe: Coded excitation, Ultrasound field distribution, Matching filtering Afiliacje autorów:
 
41.  Dynowski K.^{♦}, Litniewski J., Nowicki A., Threedimensional imaging in ultrasonic microscopy, ARCHIVES OF ACOUSTICS, ISSN: 01375075, Vol.32, No.4, pp.7177, 2007 Streszczenie: Advances in modern technology increases requirements for nondestructive characterization of material and biological properties in the μm range. The acoustic microscope presented in this paper combines Cscan and Bscan modes. The data collected during single XY scan allow to present transversal and horizontal crosssections of the sample as well as real threedimensional images of the sample interior. The system consist of several components: step motor driven mechanical scanner, transmitter/ receiver device, ADC 1 GHz board, ultrasonic heads, PCclass computer and image processing and visualization software. Image processing software is used for initial 3D image analysis of the whole image or its fragments, and for preparing it this way for vectorization. To achieve vectorization we used VTK (Visualization Tool Kit) library from Kitware Inc., which is the open source software, designed for 3D graphics and image processing. Finally isosurface is constructed and presented as 3D scene in interactive GUI (Graphical User Interface). Słowa kluczowe: 3D visualization, microscope, ultrasound Afiliacje autorów:
 
42.  Nowicki A., Klimonda Z., Lewandowski M., Litniewski J., Lewin P.A.^{♦}, Trots I., Comparison of sound fields generated by different coded excitations experimental results, Ultrasonics, ISSN: 0041624X, Vol.44, pp.121129, 2006 Streszczenie: This work reports the results of measurements of spatial distributions of ultrasound fields obtained from five energizing schemes. Three different codes, namely, chirp signal and two sinusoidal sequences were investigated. The sequences were phase modulated with 13 bits Barker code and 16 bits Golay complementary codes. Moreover, two reference signals generated as two and sixteen cycle sine tone bursts were examined. Planar, 50% (fractional) bandwidth, 15 mm diameter source transducer operating at 2 MHz center frequency was used in all measurements. The experimental data were collected using computerized scanning system and recorded using wideband, PVDF membrane hydrophone (Sonora 804). The measured echoes were compressed, so the complete pressure field in the investigated location before and after compression could be compared. In addition to a priori anticipated increase in the signal to noise ratio (SNR) for the decoded pressure fields, the results indicated differences in the pressure amplitude levels, directivity patterns, and the axial distance at which the maximum pressure amplitude was recorded. It was found that the directivity patterns of noncompressed fields exhibited shapes similar to the patterns characteristic for sinusoidal excitation having relatively long time duration. In contrast, the patterns corresponding to compressed fields resembled those produced by brief, wideband pulses. This was particularly visible in the case of binary sequences. The location of the maximum pressure amplitude measured in the 2 MHz field shifted towards the source by 15 mm and 25 mm for Barker code and Golay code, respectively. The results of this work may be applicable in the development of new coded excitation schemes. They could also be helpful in optimizing the design of imaging transducers employed in ultrasound systems designed for coded excitation. Finally, they could shed additional light on the relationship between the spatial field distribution and achievable image quality and in this way facilitate optimization of the images obtained using coded systems. Słowa kluczowe: coded excitation, sound fields Afiliacje autorów:
 
43.  Pong M.^{♦}, Umchid S.^{♦}, Guarino A.J.^{♦}, Lewin P.A.^{♦}, Litniewski J., Nowicki A., Wrenn S.P.^{♦}, In vitro ultrasoundmediated leakage from phospholipid vesicles, Ultrasonics, ISSN: 0041624X, DOI: 10.1016/j.ultras.2006.07.021, Vol.45, pp.133145, 2006 Słowa kluczowe: ultrasound exposure, therapcutic ultrasound, membraue pcrmeability, giant vesicles Afiliacje autorów:
 
44.  Trots I., Nowicki A., Lewandowski M., Litniewski J., Secomski W., Golay complementary codes, double pulse repetition frequency transmission, ARCHIVES OF ACOUSTICS, ISSN: 01375075, Vol.31, pp.3540, 2006 Streszczenie: This study concerns the development and investigation of a new composing method of short coded sequences and their transmission based on wellknown Golay complementary codes and applied compression technique allowing to increase the signaltonoise ratio (SNR) and penetration. This new method can potentially play important role in examination of superficial structures, e.g. dermatology, ophthalmology, etc. This paper reports the results of examination of the two pairs 3.5 MHz coded sequences of the same duration: the single 32bits pair Golay sequences and combined sequences consisting of two 16bits Golay codes separated in time. The results clearly demonstrate the potential of the combined coded transmission obtaining the SNR = 22.6 dB that is 2.6 dB higher than for the traditional Golay sequences and it is in case when coded length is two times shorter. For obtaining the same SNR using traditional method the code length should be at least 64 bits long, resulting in the increased dead zone up to 1.4 cm. Słowa kluczowe: Golay complementary sequences, double transmission, dead zone Afiliacje autorów:
 
45.  Litniewski J., Determination of the elasticity coefficient for a trabecula of a cancellous bone: Scanning Acoustic Microscopy approach, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 03015629, Vol.31, No.10, pp.13611366, 2005 Streszczenie: Scanning acoustic microscope techniques enable determination of mechanical properties of small samples. These techniques can be applied to a single trabecula of the cancellous bone. This paper describes nondestructive methods for assessing the bone tissue elasticity for samples accessible from one side only. Two methods are applied in the same area of a trabecula. The first one allows determination of the tissue impedance,based on the correlation between the grey levels of the scanning acoustic microscope images and of the reference material of a known impedance. The second newlydeveloped technique enables measurement of the velocity of surface waves with a spatial resolution less than 100 m, using theoretical and experimental analysis of the position of the first interference of the V(z) curve. These two experimentallyderived parameters were used to calculate the density and elasticity coefficient for trabecular bone samples of patients who suffered from metabolic bone diseases, such as osteoporosis, osteomalacia and osteoidosis. Medical descriptions of these diseases explain the differences in mechanical properties of trabecular bone tissue found experimentally. Słowa kluczowe: SAM, Trabecular bone, Elasticity, Density, Impedance, Surface wave velocity, Osteoporosis Afiliacje autorów:
 
46.  Nowicki A., Litniewski J., Secomski W., Trots I., Lewandowski M., Tymkiewicz R., Coded ultrasonography, Annual Report  Polish Academy of Sciences, ISSN: 16403754, pp.5657, 2005 
Lista ostatnich monografii
1. 123  Litniewski J., Wykorzystanie fal ultradźwiękowych do oceny zmian struktury kości gąbczastej, Rozprawa habilitacyjna, IPPT Reports on Fundamental Technological Research, 2, pp.1186, 2006 
Lista rozdziałów w ostatnich monografiach
1. 573  Gambin B., Kruglenko E., Litniewski J., Tymkiewicz R., Aktualności Inżynierii Akustycznej i Biomedycznej, rozdział: Dynamic elasticity, acoustical impedance and attenuation of special tissuelike phantoms, Polskie Towarzystwo Akustyczne, Oddział w Krakowie, I, pp.8996, 2018 
2. 494  Klimonda Z., DobruchSobczak K., PiotrzkowskaWróblewska H., Tymkiewicz R., Litniewski J., Postępy Akustyki 2016, rozdział: Obrazowanie tłumienia ultradźwięków w tkance nowotworowej, Polskie Towarzystwo Akustyczne, Oddział Warszawski, Warszawa, Poland, pp.3948, 2016 
3. 495  Litniewski J., Klimonda Z., Karwat P., PiotrzkowskaWróblewska H., DobruchSobczak K., Tymkiewicz R., Gambin B., Postępy Akustyki 2016, rozdział: Cancer malignancy sonic markers, Polskie Towarzystwo Akustyczne, Oddział Warszawski, Warszawa, Poland, pp.4960, 2016 
4. 496  PiotrzkowskaWróblewska H., Litniewski J., Postępy Akustyki 2016, rozdział: Wpływ własności rozproszeniowych ośrodka na wartości efektywnej liczby rozpraszaczy, Polskie Towarzystwo Akustyczne, Oddział Warszawski, Warszawa, Poland, Instytut Podstawowych Problemów Techniki PAN, pp.6172, 2016 
5. 326  Nowicki A., Litniewski J., Trots I., Lewandowski M., Hydroacoustics of shallow water, rozdział: Encoded Ultrasound, Wydawnictwo Instytutu Podstawowych Problemów Techniki PAN, Warszawa, pp.181208, 2013 
6. 248  Piotrzkowska H., Litniewski J., Nowicki A., Szymańska E.^{♦}, Acoustical Imaging, rozdział: STATISTICAL PROPERTIES OF ECHOSIGNAL OBTAINED FROM HUMAN DERMIS IN VIVO, Springer, Nowicki A., Litniewski J., Kujawska T. (Eds.), 31, pp.123133, 2012 
7. 261  Klimonda Z., Litniewski J., Nowicki A., Acoustical Imaging, rozdział: Enhancing tissue attenuation estimation from backscattered ultrasound using spatial compounding and synthetic aperture techniques, Springer, Nowicki A., Litniewski J., Kujawska T. (Eds.), 31, pp.181190, 2012 
8. 264  Cieślik L., Litniewski J., Acoustical Imaging, rozdział: ULTRASONIC EVALUATION OF DEEPLY LOCATED TRABECULAR BONES – PRELIMINARY RESULTS, Springer, Nowicki A., Litniewski J., Kujawska T. (Eds.), 31, pp.4552, 2012 
9. 265  Cieślik L., Litniewski J., Acoustical Imaging, rozdział: Ultrasonic Evaluation of Deeply Located Trabecular BonesPreliminary ResultsAco, Springer, Nowicki A., Litniewski J., Kujawska T. (Eds.), 31, pp.4553, 2012 
10. 307  Wójcik J., Litniewski J., Nowicki A., Acoustical Imaging, rozdział: Multiple Scattering Contribution to Trabecular Bone Backscatter, Springer, 30, pp.6977, 2011 
11. 311  Litniewski J., Klimonda Z., Nowicki A., Acoustical Imaging, rozdział: Applying Echoes Mean Frequency Shift for Attenuation Imaging in Tissue, Springer, 30, pp.97103, 2011 
12. 126  Nowicki A., Klimonda Z., Lewandowski M., Litniewski J., Lewin P.A.^{♦}, Trots I., Acoustical imaging, rozdział: Direct and postcompressed sound fields for different coded excitations, Springer, André M.P. et al (Eds.), 28, pp.399407, 2007 
13. 207  Litniewski J., Nowicki A., Dynowski K.^{♦}, Secomski W., Tissue remodelling, ABIOMED Lecture Notes 3, rozdział: Assessment of a trabecular bone status with high and low frequency ultrasounds, IPPT PAN, ABIOMED (Warszawa), Piekarski J. (Ed.), pp.173188, 2005 
Redaktor monografii
1. 266  Nowicki A., Litniewski J., Kujawska T., Acoustical Imaging, Springer, 31, pp.1400, 2012 
Prace konferencyjne
1.  Litniewski J., Tasinkevych Y., Podhajecki J., Falińska K., Combined estimation of thickness and velocity of cortical shell using reflected waves: study on bone phantoms and samples, IUS 2015, IEEE International Ultrasonics Symposium, 20151021/1024, Taipei (TW), DOI: 10.1109/ULTSYM.2015.0512, pp.14, 2015 Streszczenie: Estimation of the thickness and sound velocity of cortical bone is important per se as well as for correcting measurements of cancellous bone properties. We propose a method that allows the thickness of a compact bone layer and longitudinal wave velocity in the bone to be determined simultaneously with the use of the reflected waves, with particular emphasis on the 1mm  3mm thick bone layers corresponding to the thickness of the cortex of the human femur. The method was tested using ultrasonic data obtained from cortical bone phantoms and a fresh calf bone specimen. The results show that the method seems to be well suited to be employed for the determination of the thickness and acoustic wave velocity of the cortical bone layer. Słowa kluczowe: Cortical bone, trabecular bone, thickness and velocities of cortical shell, reflected waves, BUA Afiliacje autorów:
 
2.  Byra M., Nowicki A., Piotrzkowska H., DobruchSobczak K., Litniewski J., Correcting the influence of tissue attenuation on Nakagami distribution shape parameter estimation, IUS 2015, IEEE International Ultrasonics Symposium, 20151021/1024, Taipei (TW), DOI: 10.1109/ULTSYM.2015.0408, pp.P1B634, 2015 Streszczenie: Nakagami distribution is used to model the statistical properties of backscattered echoes in tissue. The proper estimate requires the compensation of attenuation along each scanning line. Attenuation of the wave results in decreasing of the envelope mean intensity with depth what modifies the Nakagami scale parameter. This phenomenon violates the assumption that envelope samples within region of interest are identically distributed and disrupts estimation. Here, we investigate the influence of wave attenuation on Nakagami shape parameter estimators for various scattering scenarios, attenuation coefficients and region of interest size. Three methods are proposed to solve this issue. Scans of a thyroid and of a breast lesion are analyzed. It was found that proposed methods improved the estimation, especially when larger regions were used to collect envelope samples. Słowa kluczowe: ultrasound, breast cancer, Nakagami distribution Afiliacje autorów:
 
3.  Nowicki A., Piotrzkowska H., DobruchSobczak K., Litniewski J., Byra M., Gambin B., Kruglenko E., Differentiation of normal tissue and tissue lesions using statistical properties of backscattered ultrasound in breast, IUS 2015, IEEE International Ultrasonics Symposium, 20151021/1024, Taipei (TW), DOI: 10.1109/ULTSYM.2015.0417, pp.P1B6154, 2015 Streszczenie: The aim of the study was finding the relationship between BIRADS classification combined with envelope K and Nakagami statistics of the echoes backscattered in the breast tissue in vivo and the histological data. 107 breast lesions were examined. Both, the RF echosignal and Bmode images from the lesions and surrounding tissue were recorded. The analysis method was based on the combining data from BIRADS classifications and both distributions parameters. 107 breasts lesions  32 malignant and 75 benign  were examined. When only BIRADS classification was used all malignant lesions were diagnosed correctly, however 34 benign lesions were sent for the biopsy unnecessarily. For K distribution the sensitivity and specificity were 78.13%, and 86.67% while for Nakagami statistics the sensitivity and specificity were 62.50% and 93.33%, respectively. Combined K and BIRADS resulted in sensitivity of 96.67% and specificity 60%. Combined BIRADS (3/4a cutoff) plus Nakagami statistics showed 100% of sensitivity with specificity equal 57.33%, decreasing the number of lesions which were biopsied from 34 to 28. Słowa kluczowe: breast cancer, quantitative ultrasound, BIRADS Afiliacje autorów:
 
4.  Litniewski J., Piotrzkowska H., Nowicki A., Szymańska E.^{♦}, Statistics of envelope of Ultrasonic Backscatter from Basal Cell Carcinoma and Actinic Keratosis lesion, IUS 15, IEEE International Ultrasonics Symposium, 20140903/0906, Chicago (US), DOI: 10.1109/ULTSYM.2014.0474, pp.19081911, 2014 Streszczenie: Basal cell carcinoma is the most common cutaneous malignancy, representing 80% of all skin cancer cases. The quantitative ultrasound can provide information potentially helpful in diagnosing. The goal of this study was to find the quantitative measure of the skin tissue backscattering properties that could be used for differentiating the changes of tissue structure induced by Basal Cell Carcinoma (BCC) and precancerous lesions  Actinic Keratosis (AK). The study presents the results concerning the statistical properties of ultrasonic echoes scattered in cancer lesions and attenuation coefficient determined from the backscatter. Słowa kluczowe: tissue characterization, quantitative ultrasound,skin lesions, statistical distribution, attenuation coefficient Afiliacje autorów:
 
5.  Nowicki A., Byra M., Litniewski J., Wójcik J., Two Frequencies PushPull Differential Imaging, IUS 15, IEEE International Ultrasonics Symposium, 20140903/0906, Chicago (US), DOI: 10.1109/ULTSYM.2014.0175, pp.710713, 2014 Streszczenie: Nowadays there are new modalities in ultrasound imaging allowing better characterization of tissue regions with different stiffness. We are proposing an approach based on simultaneous propagation of two waves being a combination of two pulses differing in pressure and frequency: 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 bandpass 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. Afiliacje autorów:
 
6.  Klimonda Z., Litniewski J., Nowicki A., Compounded plane wave technique applied to imaging attenuation of ultrasound in tissue structures, FA2014, 7th FORUM ACUSTICUM 2014, 20140907/0912, Kraków (PL), No.SS27_1, pp.15, 2014 Streszczenie: The parametric imaging can enhance ultrasonic examinations that are widely used in medical diagnostics. Attenuation of the wave propagating through the soft tissue reflects the state of the tissue, what is clearly demonstrated in literature. The visualization of the spatial distribution of attenuation may support the diagnosis by accurate discrimination of the lesions from normal tissue at the early stage of the disease. This research is focused on the developing of the method of attenuation estimation from ultrasonic backscatter. It would allow to produce the parametric images from the same data as the standard Bmode images. The attenuation estimation method bases on the spectral mean frequency (fm) downshift of the propagating pulse, that results from the frequency dependence of attenuation. The fm was determined (using fm correlation estimator and trend extraction with Single Spectrum Analysis algorithm) from the ultrasonic echoes scattered in the tissue mimicking phantom which contained a cylinder with the attenuation coefficient higher than in the background. The data acquisition were performed using ultrasonic scanner. The earlier research indicated the effectiveness of attenuation estimation method using the synthetic aperture technique to collect the data. The use of the synthetic transmit aperture scheme to acquire the data results in better attenuation imaging comparing to standard beamforming, however it lower the penetration depth. In this research the compounded plane wave transmitreceiving scheme was used, to improve the penetration range. Compensation for the diffraction effects was included in the data processing. The results indicate suitability of this approach for attenuation imaging. We can measure attenuation in the tissue mimicking materials with the spatial resolution of approximately 10mm and accuracy of 0.2dB/(MHz·cm). In the presentation, the attenuation images of tissue mimicking phantoms and the images of human liver, obtained in vivo, will be presented. Słowa kluczowe: attenuation imaging, plane wave imaging Afiliacje autorów:
 
7.  Piotrzkowska H., Nowicki A., Litniewski J., Gambin B., DobruchSobczak K.^{♦}, Breast carcinoma tissues characterization using statistics of ultrasonic backscatter, FA2014, 7th FORUM ACUSTICUM 2014, 20140907/0912, Kraków (PL), No.SS27_7, pp.19, 2014 Streszczenie: The Ultrasonix SonixTouch scanner with the special RF block was used to collect Bmode images together with appropriate RF echoes from the pathological and healthy breasts regions of patients with diagnosed malignant and benign breast lesions. The RF data were processed for the statistics of the backscattered echo signals assessment (K distribution and effective density of scatterers – M and Nakagami distribution and its shape parameter m). The comparison of signals recorded from malignant and healthy tissues showed, that in 80% of examined cases the values of the statistical parameters M were higher for carcinomas tissues than for healthy tissue. Beside of that in the case of benign lesions obtained results was able to distinguish the fibroadenoma from the other with probability of 75%. Słowa kluczowe: quantitative ultrasound, breast cancer, statistics Afiliacje autorów:
 
8.  Doubrovina O.^{♦}, Litniewski J., Gambin B., Wavelet approximations and statistical approach to random fluctuations of amplitude in backscattered ultrasonic signal, FA2014, 7th FORUM ACUSTICUM 2014, 20140907/0912, Kraków (PL), No.SS27_2, pp.16, 2014 Streszczenie: The goal of this study was to find the macroscopic characteristics of the random nature of ultrasonic backscattering signals which would be sensitive to the temperature changes. The sample made of Polyvinyl Alcohol – Cryogel (PVAC, the prefreezing in one cycle aqueous solution of PVA) was heated in a water bath starting from the room temperature up to the temperature below the soft tissue ablation temperature. The RF signals were collected during the heating/cooling process and the signals envelopes had been calculated. The wavelet approximation of subsequent level worked as a lowpass filter what qualitatively improved the temperature estimating. The latter was realized by observing the variations of the shape parameter of Kdistribution. The trend of the shape parameter variation with temperature was calculated including the wavelet decomposition and was compared with the real temperature changes measured by the thermometer. We have found that tracking changes in echoes envelope statistics allows to distinguish between heating and cooling process, and determine the time required to reach maximum temperature. Słowa kluczowe: random signals, Polyvinyl Alcohol – Cryogel, wavelet approximation, temperaturę monitoring Afiliacje autorów:
 
9.  Piotrzkowska H., Litniewski J., Nowicki A., Szymańska E.^{♦}, Basal Cell Carcinoma Lesions Characterization With Ultrasound, IUS 2012, IEEE International Ultrasonics Symposium, 20121007/1010, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0596, pp.16, 2012 Streszczenie: Quantitative ultrasounds were applied for the detection and assessment of skin lesions. 30MHz ultrasonic scanner was used to collect Bscan images together with appropriate RF echoes from the pathological and healthy skin regions of skin of patients with diagnosed Basal Cell Carcinoma and precancerous states. The RF data were processed for the attenuation coefficient and statistics assessment (K distribution and effective number of scatterers – M). For patients with BCC the attenuation coefficient was significantly higher than for the healthy skin ones. Also, precancerous skin lesions revealed increased attenuation. The averaged M parameter for cancer lesions was significantly lower than for precancerous states and healthy skin. Similar results were obtained from numerical simulations of the ultrasonic echoes scattered in skin and skin lesions. Słowa kluczowe: skin cancer, K distribution, effective number of scatterers, high frequency ultrasound Afiliacje autorów:
 
10.  Litniewski J., Wójcik J., Nowicki A., Contribution of multiple scattering to the trabecular bone backscatter  dependence on porosity and frequency, IUS 2012, IEEE International Ultrasonics Symposium, 20121007/1010, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0650, pp.14, 2012 Streszczenie: Scatteringbased ultrasonic methods potentially enable assessment of microscopic structure of bone. In our previous study we have shown how to account the higher orders of scattering in the backscatter evaluation. Here, the role of multiple scattering in bone backscatter is assessed for the varying bone porosity. The set of integral equations corresponding to the singular Sturm–Liouville equation was solved numerically allowing for the calculation of the field scattered forward and backward in the bone model. The results indicate that for the porosities below 85% the approximation of the first order scattering is not valid for all considered frequencies. The Laue’s equations were applied to explain considerable increase of the scattering at some frequencies. It was shown that the deformation of trabecular mesh results in flattening of the scattering peaks Słowa kluczowe: trabecular bone, ultrasounds scattering, multiple scattering Afiliacje autorów:
 
11.  Klimonda Z., Litniewski J., Nowicki A., Correcting for bounded bandwidth when estimating tissue attenuation from mean frequency downshift, IUS 2012, IEEE International Ultrasonics Symposium, 20121007/1010, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0413, pp.16471650, 2012 Streszczenie: The attenuation of tissue can be estimated utilizing the downshift of the center frequency of a propagating pulse. In general it is assumed that the shape of the emitted pulse can be approximated by a Gaussian function and attenuation is assumed to change linearly with frequency. At this conditions the downshift of the mean frequency of pulse spectrum depends linearly on attenuation coefficient, pulse bandwidth and propagation distance. This is a good approximation for relatively narrowband pulses and small penetration depth. But for short pulses and deep penetration the frequency downshift is large and the ultrasonic pulse is no more Gaussian, thus the previous assumption is no longer correct. The closer is the mean frequency of the pulse to the lower frequency bound of the receiving system the bigger deformation of the pulse spectrum occurs and consequently the attenuation is determined with bigger error. The following paper presents how to correct the experimentally determined mean frequency and to obtain reliable results when investigating tissue attenuation with wideband pulses. We propose a new formula for the dependence between pulse mean frequency, tissue attenuation, pulse bandwidth and traveled distance. The formula was derived from the mean frequency of Gaussian pulse spectrum determined in the limited frequency band. The formula was applied to simulate variation of mean frequency MF of the pulse propagating in the medium with attenuation coefficient corresponding to the attenuation in the tissue mimicking phantom. The MF was also determined (using the correlation estimator of MF and next trend extraction using Single Spectrum Analysis) from the simulated ultrasonic echoes and echoes scattered in the tissue phantom. The corrected nonlinear formula describes well MF variation along the pulse propagation path. The departure from the linear dependence increases with large MF shift, thus it is well pronounced for highly attenuating tissue, the wideband pulses and deep penetration. Słowa kluczowe: attenuation estimation, frequency downshift Afiliacje autorów:
 
12.  Klimonda Z., Litniewski J., Karwat P., Secomski W., Nowicki A., Tissue attenuation imaging  Synthetic Aperture Focusing versus Spatial Compounding, IUS 2012, IEEE International Ultrasonics Symposium, 20121007/1010, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0590, pp.23612363, 2012 Streszczenie: The long term goal of this research is to develop the system enabling the imaging and quantitative measure of ultrasonic attenuation in tissue. It may support the diagnosis by accurate discrimination of the lesions from normal tissue at the early stage of the disease. The attenuation is estimated from the stochastic ultrasonic backscatter and time/spatial averaging is necessary to achieve reasonable accuracy. However the averaging worsens the spatial resolution. Two techniques of ultrasonic imaging, the Synthetic Aperture Focusing technique (SAFT) and Spatial Compounding (SC), were applied and compared with respect to the quality of attenuation estimation. The ultrasonic RF data were collected from a tissue mimicking phantom using ultrasonic scanner (Ultrasonix SonixTOUCH). Both acquired echoessets were processed in the same way in order to calculate the downshift in a mean frequency fm of the backscatter signal and resulting spatial distribution of attenuation coefficient. Compensation for the diffraction effects was included in the data processing. The RF data obtained with use of the SAFT proved to be more suitable for attenuation estimation. Słowa kluczowe: tissue attenuation imaging, synthetic aperture, spatial compounding Afiliacje autorów:
 
13.  Karwat P., Litniewski J., Secomski W., Kujawska T., Krawczyk K., Kruglenko E., Gambin B., Nowicki A., Nieinwazyjne obrazowanie temperatury tkanki miękkiej in vitro metodą analizy przemieszczenia ech ultradźwiękowych, 59th Open Seminar on Acoustics, 20120910/0914, Boszkowo (PL), pp.101104, 2012 Streszczenie: Terapeutyczne i chirurgiczne zastosowania ogniskowych ultradźwięków wymagają monitorowania lokalnych zmian temperatury w tkance. Najkorzystniejsze z punktu widzenia użytkowego i ekonomicznego byłoby zastosowanie do tych celów technik ultradźwiękowych. Słowa kluczowe: obrazowanie temperatury, prędkość akustyczna Afiliacje autorów:
 
14.  Kruglenko E., Mizera A., Gambin B., Tymkiewicz R., Zienkiewicz B., Litniewski J., Nagrzewanie ultradźwiękami tkanek miękkich in vitro i własności akustyczne wytworzonych wzorców tkanek miękkich, 59th Open Seminar on Acoustics, 20120910/0914, Boszkowo (PL), pp.129132, 2012 Streszczenie: W pracy przedstawiono wstępne wyniki pomiaru pola temperatury wewnątrz tkanki in vitro w czasie procesu nagrzewania wiązką ultradźwiękową o słabej mocy oraz pomiaru właściwości akustycznych wzorców tkanek miękkich. Wzorce te zbudowano w celu dalszych badań nad powiązaniem wzrostu temperatury z właściwościami akustycznymi, gdyż próbki tkankowe in vitro okazały się niepowtarzalne i nietrwałe. Na wykonanych 3 wzorcach tkankowych dokonano pomiaru sygnału przejścia i wyznaczono prędkość propagacji impulsu, współczynnik tłumienia oraz zbadano statystykę rozproszenia. Przedyskutowano wpływ liczby elementów rozpraszających na te wielkości. Słowa kluczowe: wzorce tkanek, sygnał ultradźwiękowy, prędkość dźwięku, tłumienie, statystyka rozproszenia Afiliacje autorów:
 
15.  Klimonda Z., Litniewski J., Nowicki A., Zastosowanie uśredniania częstotliwościowego i przestrzennego przy estymacji tłumienia w tkance miękkiej, 59th Open Seminar on Acoustics, 20120910/0914, Boszkowo (PL), Vol.1, pp.14, 2012 Streszczenie: Standardowe obrazy ultrasonograficzne przestawiają rozkład zmian impedancji akustycznej wewnątrz tkanki. Możliwe jest jednak obrazowanie innych parametrów akustycznych. Takie parametryczne obrazy dostarczałyby dodatkowych informacji o stanie tkanki, przydatnych w diagnostyce. Zmiany wartości współczynnika tłumienia fali ultradźwiękowej często towarzyszą patologicznym zmianom struktury tkanki, np. nowotworom. Jedną z metod estymacji tłumienia jest metoda bazująca na przesunięciu częstotliwości średniej widma sygnału w czasie jego propagacji w tkance. Główną niedogodnością metody jest duża wariancja otrzymywanych estymat. W niniejszej pracy przedstawiono rezultaty zastosowania metod uśredniania przestrzennego i częstotliwościowego w celu polepszenia jakości otrzymywanych obrazów rozkładu tłumienia. Weryfikacje metod przeprowadzono w oparciu o dane symulacyjne i dane z fantomu tkankowego o stałej echogeniczności i zmiennym tłumieniu. Słowa kluczowe: estymacja tłumienia, uśrednianie przestrzenne, uśrednianie częstotliwościowe Afiliacje autorów:
 
16.  Karwat P., Litniewski J., Secomski W., Kujawska T., Krawczyk K., Kruglenko E., Gambin B., Noninvasive imaging of thermal fields induced in soft tissues in vitro by focused ultrasound using analysis of ultrasonic echoes displacement, International Conference Biomedical Engineering, 20121025/1026, Kaunas (LT), pp.6672, 2012 Streszczenie: Therapeutic and surgical applications of focused ultrasound require monitoring of local temperature rises induced inside tissues. From an economic and practical point of view ultrasonic imaging techniques seem to be the best for a temperature control. In this work an attempt to apply the method of the ultrasonic echoes displacement estimation for monitoring local temperature rises in tissues during their heating by focused ultrasound is presented. The estimated temperature rise was compared with this measured by a thermocouple. The obtained results enable to evaluate the temperature fields induced in tissues by pulsed focused ultrasonic beams using noninvasive imaging ultrasound technique. Słowa kluczowe: HIFU, therapeutic ultrasound, ultrasonic imaging, echo strain estimation Afiliacje autorów:
 
17.  Piotrzkowska H., Litniewski J., Szymańska E.^{♦}, Nowicki A., Skin lesions assessment using attenuating and statistical properties of the backscattered ultrasound, IUS 2011, IEEE International Ultrasonics Symposium, 20111018/1021, Orlando (US), DOI: 10.1109/ULTSYM.2011.0338, pp.13681371, 2011 Streszczenie: While the needles biopsy is still the gold standard in skin cancer diagnosis there is a growing interest in application of the high frequency ultrasound for the skin lesions detection and their thickness assessment. The quantitative ultrasound can provide additional information, potentially helpful in diagnosis. The purpose of this study was to assess the usefulness of the attenuating and statistical properties of the backscattered ultrasounds for the skin tissues characterization. The paper presents the classification of the healthy skin and skin lesions (BCCbasal cell carcinoma and AKactinic keratosis). For patients with BCC the attenuation coefficient was significantly higher than for the healthy ones. Also, precancerous skin lesions revealed increased attenuation. The statistical properties were different for BCC comparing to AK lesions and healthy skin. Słowa kluczowe: basal cell carcinoma, actinic keratosis, attenuation coefficient, statistical properties, high frequency ultrasound Afiliacje autorów:
 
18.  Litniewski J., Cieślik L., Lewandowski M., Tymkiewicz R., Zienkiewicz B., Nowicki A., Bone scanner for examination of deeply located trabecular bones, IUS 2011, IEEE International Ultrasonics Symposium, 20111018/1021, Orlando (US), DOI: 10.1109/ULTSYM.2011.0117, pp.486489, 2011 Streszczenie: The paper presents a new yield criterion for the transversal isotropy of metal sheets under planestress conditions which is an extension of the isotropic yield function proposed by Burzynski (Burzynski W. l928). Studium nad hipotezami Burzynski's doctoral dissertation "Study on material effort hypotheses”, Engng. Trans., 2009, t. 57, nr 34, s. l852l5). Two additional coefficients have been introduced in order to allow a better representation of plastic behavior of metal sheets. The proposed yield condition includes the influence of first invariant of the stress tensor and also the strength differential effect. The system of equations describing the sheet metal forming process is solved by algorithm using the return mapping procedure. PIane stress constraint is incorporated into the NewtonRaphson iteration loop. The proposed algorithm is verified by performing a numerical test using shell elements in commercial FEM software ABAQUS/EXPLICIT with a developed VUMAT subroutine. It is shown that the proposed approach provides the satisfactory prediction of material behavior, at least in the cases when anisotropy effects are not advanced. To perform FE simulations of cup deep drawing processes, three independent yield stresses are required. Those yield stresses can be obtained from: directional uniaxial tensile test, directional uniaxial compression test and equibiaxial compression tests. In the paper the formability of two metal sheets are analysed. First the influence of strength differential effect on the cup height profile is shown. Then the comparison between the HuberMisesHencky yield condition and the proposed yield condition is presented. Słowa kluczowe: bone scanner, trabecular bone, osteoporosis Afiliacje autorów:
 
19.  Litniewski J., Cieslik L.^{♦}, Wójcik J., Nowicki A., Statistical properties of trabecular bone backscatter: experimental and simulations results, IUS 2010, IEEE International Ultrasonics Symposium, 20101011/1014, San Diego (US), DOI: 10.1109/ULTSYM.2010.5935557, Vol.1, pp.21552158, 2010 Streszczenie: The presented investigations were intended to compare the experimental results obtained from the heel bones in vivo with the results of simulations. Ultrasonic RF echoes were collected using two bone scanners operating at 0.58 MHz and 1.3 MHz. The simulations of the backscattered RF echoes were performed using the scattering model of the trabecular bone that consisted of cylindrical and spherical elements uniformly distributed in water. For each measured or simulated RF backscatter statistical properties of the signal envelope was determined. Experimental results suggest deviations from the Rayleigh distribution. Simulation results suggest that deviations from Rayleigh distribution depend on the variation of trabeculae diameters and the number of thin trabeculae. Experimentally determined deviations corresponded well with the deviations calculated from simulated echoes assuming trabeculae thickness variation equal to published histomorphometric study results. Słowa kluczowe: trabecular bone, scattering, statistical properties Afiliacje autorów:
 
20.  Wójcik J., Litniewski J., Nowicki A., Multiple Scattering Contribution to Trabecular Bone Backscatter, 10ème Congrès Français d'Acoustique, 20100412/0416, Lyon (FR), Vol.1, No.CD file: 000361.pdf, pp.16, 2010 Streszczenie: Trabecular bone consists of trabeculae which mechanical properties differ significantly from the surrounding marrow and therefore the ultrasonic wave is strongly scattered within the bone structure. The aim of the presented paper was the evaluation of the contribution of the first, second and higher order scattering (multiple scattering) into total scattering of ultrasounds in the trabecular bone. The scattering due to interconnections between thick trabeculae, usually neglected in trabecular bone models, has been also studied. The basic element in our model of trabecular bone was an elastic cylinder with finitelength and varying diameter and orientation. The applied model was taking into account variation of elements size and spatial configuration. The field scattered on the bone model was evaluated by solving numerically the integral form of the SturmLiouville equation that describes scalar wave in inhomogeneous media. For the calculated scattered fields the effective crosssections as well as the Broadband Ultrasonic Backscatter (BUB) were determined. The influence of the absorption on scattering coefficients was demonstrate. The results allowed to conclude that within the frequency range from 0.5 to 1.5 MHz the contribution of the second order scattering to the effective backscattering crosssection is at least 500 times lower than the one due to the first order scattering. BUB, calculated under the same assumptions, is 20 times lower. Above the 1.5 MHz the fast growth of the BUB, calculated for the second order scattering, occurs. Słowa kluczowe: Complex media, Modeling, Multiple scattering, Trabecular bone,Ultrasound Afiliacje autorów:
 
21.  Litniewski J., Nowicki A., Wójcik J., Ultrasonic characterization of cancellous bone using three models of trabecular structure, 159th Meeting of the Acoustical Society of America and NOISECON 2010, 20100419/0423, Baltimore (US), Vol.9, No.020002, pp.19, 2010 Streszczenie: The semiempirical scattering models of trabecular bone were developed and examined for their abilities to mimic the frequency dependent backscattering coefficient measured in the cancellous bone. In the simulation of the bone RF echoes the real properties of the bone and experimental conditions were taken into account. Three types of trabeculae mimicking scatterers were considered. First, the bone consisted of cylinders with varying thickness (Gamma distributed) within the population, was assumed. The next two cases accounted for the contribution of thick and thin trabeculae to the total backscattered signal. The second model assumed existence of two populations of the cylindrical scatterers significantly differing in the average value of Gamma distributed diameters. Finally, the mixed model composed of thick and thin trabeculae modeled respectively by cylindrical and spherical scatterers was examined. The last selection resulted from the similarity found between scattering on small sphere and finite cylinder. Calculated echoes demonstrated the usefulness of the mixed model. Frequency dependence of backscattering coefficient agreed well with the experimentally determined dependences. The study showed also that the amplitude histograms calculated using demodulated RF echoes deviate from the Rayleigh distribution when the variation of scatterers’ diameters increases. Słowa kluczowe: trabecular bone structure, modeling, backscatter Afiliacje autorów:
 
22.  Litniewski J., Wójcik J., Nowicki A., Scattering model of trabecular bone, 57 Otwarte Seminarium z Akustyki, 20100920/0924, Gliwice (PL), pp.117120, 2010 Streszczenie: In our previous study we have developed the simulation technique that enables determination of the ultrasound signal received at the pulseecho transducer surface after interrogation of cancellous bone. The simulation can be applied for different scattering models of a trabecular structure. In this study we examined newly developed scattering models of the trabecular bone for their abilities to mimic the frequency dependent backscattering coefficient measured in the cancellous bone. Three types of trabeculae mimicking scatterers were considered. First the bone consisted of cylinders with varying thickness (Gamma distributed) within the population, was assumed. The next two cases accounted for the contribution of thick and thin trabeculae to the total backscattered signal. The second model assumed existence of two populations of the cylindrical scatterers significantly differing in the average value of Gamma distributed diameters. Finally, the mixed model composed of thick and thin trabeculae modeled respectively by cylindrical and spherical scatterers was examined. The last selection resulted from the similarity found between scattering on small sphere and finite cylinder. Calculated echoes demonstrated the usefulness of the mixed model. Frequency dependence of backscattering coefficient agreed well with the experimentally determined dependences. Słowa kluczowe: trabecular bone, scattering, bone model Afiliacje autorów:
 
23.  Cieślik L., Litniewski J., Lewandowski M., Nowicki A., Bone ultrasonic scanner, 57 Otwarte Seminarium z Akustyki, 20100920/0924, Gliwice (PL), pp.4952, 2010 Streszczenie: Acoustical waves scattered in trabecular bone contain information about its microstructural properties. These properties may change on course of a disease. Standard ultrasonic examinations of bone (densitometry) are performed in transmission and does not provide complete information about bone strength. We have developed the bone ultrasonic scanner that enables measurements of the physical properties of trabecular bone microstructure. Thus the evaluation of bone properties using ultrasonic scanner may be essential for bone diseases diagnosis and treatment monitoring. This study presents application of the scanner operating at 1,5 MHz frequency for examination of trabecular bone (calcaneus) . Backscattered data were collected and processed in order to obtain power backscattering coefficient (PBSC). Calculated values were compared to these published by several authors in order to verify ultrasonic scanner application as a tool for trabecular bone examination. This study is an approach towards developing a method for the investigation of scattering in trabecular bone that can potentially provide clinically useful information about bone strength and condition. Słowa kluczowe: trabecular bone, bone scanner, osteoporosis Afiliacje autorów:
 
24.  Klimonda Z., Litniewski J., Nowicki A., Tissue attenuation estimation from backscattered ultrasound using spatial compounding technique  preliminary results, 57 Otwarte Seminarium z Akustyki, 20100920/0924, Gliwice (PL), pp.9598, 2010 Streszczenie: The pathological states of biological tissues are often connected with 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 hanges 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 mean frequency trends extraction. 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 with uniform echogenicity but varying attenuation coefficient (DFS, Denmark). Słowa kluczowe: tissue attenuation estimation, spatial compounding Afiliacje autorów:
 
25.  Litniewski J., Klimonda Z., Lewandowski M., Nowicki A., Szymańska E.^{♦}, Correcting for focusing when estimating tissue attenuation from mean frequency shift, IUS 2009, IEEE International Ultrasonics Symposium, 20090920/0923, Rzym (IT), DOI: 10.1109/ULTSYM.2009.5441930, pp.23832385, 2009 Streszczenie: Determination of attenuating properties of the tissue from the echoes of waves emitted by the focused transducer requires to compensate the echo signal for the effects of focusing. We propose the diffraction/focusing effects correcting (FC) technique that compensates focusinginduced mean frequency Słowa kluczowe: attenuation estimation, difraction correction, parametric imaging Afiliacje autorów:
 
26.  Trots I., Nowicki A., Secomski W., Litniewski J., Lewandowski M., Transducer Bandwidth Influence on the Golay Encoded Ultrasound Echoes, IUS, IEEE Ultrasonics Symposium, 20071028/1031, New York (US), DOI: 10.1109/ULTSYM.2007.320, pp.12741277, 2007 Streszczenie: This paper investigates the effect of ultrasound imaging transducer’s fractional bandwidth on the gain of the compressed echo signal for different spectral widths of the complementary Golay sequences (CGS). Two different bit lengths were investigated, specifically one and two cycles. Three transducers having fractional bandwidth of 25%, 58% and 80% and operating at frequencies 6 MHz, 4.4 MHz and 6 MHz, respectively were examined (one of the 6 MHz sources was made of composite material). The experimental results have shown that by increasing the code length, i.e. decreasing the bandwidth, the compressed echo amplitude could be enhanced. The smaller the bandwidth was the larger was the gain; the pulseecho sensitivity of the echo amplitude increased by 1.88, 1.62 and 1.47, for 25%, 58% and 80% bandwidths, respectively. These results indicate that two cycles bit length excitation is more suitable for use with bandwidth limited commercially available imaging transducers. Further, the time resolution is retained for transducers with two cycles excitation providing the fractional bandwidth is lower than approximately 90%. The results of this work indicate that adjusting the code length allows signaltonoiseratio (SNR) to be enhanced while using limited (less that 80%) bandwidth imaging transducers. Also, for such transducers two cycles excitation would not decrease the time resolution, obtained with ’conventional’ spike excitation. These results also indicate that CGS excitation could be successfully implemented with the existing, relatively narrow band imaging transducers without the need to use usually more expensive wideband, composite ones. Słowa kluczowe: ultrasound imaging, coded transmission, transducer badnwidth, Golay codes Afiliacje autorów:

Abstrakty konferencyjne
1.  Klimonda Z., DobruchSobczak K., PiotrzkowskaWróblewska H., Tymkiewicz R., Litniewski J., Ultrasound attenuation imaging of tumor tissue, OSA 16, LXIII Otwarte Seminarium z Akustyki, 20160913/0916, Białowieża (PL), DOI: 10.1515/aoa20160059, pp.619620, 2016 Słowa kluczowe: attenuation estimation, parametric imaging Afiliacje autorów:
 
2.  PiotrzkowskaWróblewska H., Litniewski J., Influece of Scattering Conditions of the Medium on the Value of the Effective Number of Scatters, OSA 16, LXIII Otwarte Seminarium z Akustyki, 20160913/0916, Białowieża (PL), DOI: 10.1515/aoa20160059, No.3, pp.625, 2016  
3.  Litniewski J., Klimonda Z., Karwat P., PiotrzkowskaWróblewska H., DobruchSobczak K., Tymkiewicz R., Gambin B., Cancer Malignancy Sonic Markers, OSA 16, LXIII Otwarte Seminarium z Akustyki, 20160913/0916, Białowieża (PL), DOI: 10.1515/aoa20160059, No.3, pp.622, 2016  
4.  Nowicki A., DobruchSobczak K., Piotrzkowska H., Litniewski J., Gambin B., Roszkowska K.^{♦}, Chrapowicki E.^{♦}, Clinical Validation of the Statistical Analysis of US RF Signals in Differentiation of the Breast Lesions, AIUM 2015, Ultrasound in Medicine and Biology Annual Convention, 20150321/0325, Lake Buena Vista (US), DOI: 10.1016/j.ultrasmedbio.2014.12.403, Vol.41, No.4S, Special issue: 2015 AIUM Annual Convention and Preconvention Program Hosting WFUMB Congress, ABSTRACT 2088809, pp.S98S99, 2015 Streszczenie: The scattering is the fundamental phenomena used for US imaging of specific organs. In this study the method searching for best fitted statistical distribution of the acquired echoes from the breast tissue is discussed, especially addressing the ‘‘effective’’ number of scatterers. The aim of the study was finding the relationship between the specific properties of statistics of envelope of the ultrasonic echoes backscattered in the breast tissue in vivo, and its morphological properties for normal tissue and the pathological lesions. Słowa kluczowe: breast cancer, ultrasound, RF echosignal Afiliacje autorów:

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392950 20101115 BUP 11/12 20120521  Litniewski J. Ultradźwiękowy sposób diagnostyki osteoporozy oraz urządzenie do realizacji tego sposobu PL, Instytut Podstawowych Problemów Techniki PAN     