Marcin Lewandowski, Ph.D.

Department of Experimental Mechanics (ZMD)
Division of Non-Destructive Testing (PBN)
Laboratory of Professional Electronics
position: assistant professor
telephone: (+48) 22 826 12 81 ext.: 407
room: 539
e-mail: mlew

Doctoral thesis
2009-06-18Ultrasonografia kodowana - transmisja i kompresja w czasie rzeczywistym 
supervisor -- Prof. Andrzej Nowicki, Ph.D., Dr. Habil., Eng., IPPT PAN
631
 
Recent publications
1.Wójcik J., Lewandowski M., Żołek N., Grating Lobes Suppression by Adding Virtual Receiving Subaperture in Synthetic Aperture Imaging, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2016.12.013, Vol.76, pp.125-135, 2017
Abstract:

A method of suppression of grating lobes is presented, analyzed, and verified. The method is based on creating a Virtual Receiving Subaperture (VRS) by adding virtual transducer elements not existing in the physical layout of the receiver. The VRS channels are filled with data based on signals from real channels. The analytical model of the synthetic aperture imaging system’s impulse response is presented to describe the properties of the VRS. The model shows a reduction of the receiving grating lobes’ amplitude (with a comparison to the main lobe’s amplitude) by a magnitude equal to the number of receiving transducer elements. It is shown that effective properties of the entire system with a VRS are similar to a system with a pitch in the receiving aperture that is twice as small. The numerical calculations of the impulse response show a doubling of the signal to noise ratio, which results in a reduction of the receiving grating lobes. For experimental validation, the generalized Plane Wave Imaging with and without the VRS is compared with a basic synthetic transmit aperture (STA) imaging. The experiment confirmed that the use of a VRS allows for visualizat ion of the objects in a medium in which they are not imaged without a VRS or are visualized with a lower contrast. The reduction of grating lobes attained using the proposed method is at the level of 15dB in the visualization of the superficial cyst.

Keywords:

Grating lobes, Image quality, Synthetic aperturę, Virtual subaperture

Affiliations:
Wójcik J.-IPPT PAN
Lewandowski M.-IPPT PAN
Żołek N.-IPPT PAN
2.Lewandowski M., Walczak M., Karwat P., Witek B., Karłowicz P., Research and Medical Transcranial Doppler System, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.1515/aoa-2016-0074, Vol.41, No.4, pp.773-781, 2016
Abstract:

A new ultrasound digital transcranial Doppler system (digiTDS) is introduced. The digiTDS enables diagnosis of intracranial vessels which are rather difficult to penetrate for standard systems. The device can display a color map of flow velocities (in time-depth domain) and a spectrogram of a Doppler signal obtained at particular depth. The system offers a multigate processing which allows to display a number of spectrograms simultaneously and to reconstruct a flow velocity profile.
The digital signal processing in digiTDS is partitioned between hardware and software parts. The hardware part (based on FPGA) executes a signal demodulation and reduces data stream. The software part (PC) performs the Doppler processing and display tasks. The hardware-software partitioning allowed to build a flexible Doppler platform at a relatively low cost.
The digiTDS design fulfills all necessary medical standards being a new useful tool in the transcranial field as well as in heart velocimetry research.

Keywords:

Doppler system, digital signal processing, hardware-software partitioning, field programmable gate arrays

Affiliations:
Lewandowski M.-IPPT PAN
Walczak M.-IPPT PAN
Karwat P.-IPPT PAN
Witek B.-IPPT PAN
Karłowicz P.-other affiliation
3.Dębowski T., Lewandowski M., Mackiewicz S., Ranachowski Z., Schabowicz K., Badania ultradźwiękowe płyt włóknisto-cementowych, PRZEGLĄD SPAWALNICTWA, ISSN: 0033-2364, Vol.88, No.10, pp.69-71, 2016
Abstract:

W artykule przedstawiona została możliwość lokalizacji delaminacji w płycie włóknisto-cementowej za pomocą specjalnie do tego celu skonstruowanego urządzenia wykorzystującego metodę ultradźwiękową i fale podłużne. Przeprowadzono badania na trzech rodzajach płyt. Stwierdzono, że proponowana metoda diagnostyczna umożliwia wykrywanie lokalnych nieciągłości, np. obszarów o obniżonej zwartości, czy delaminacji w płytach włóknisto-cementowych na obszarze średnicy wiązki metodą estymacji prędkości fali ultradźwiękowej. Zaletami metody są niewielkie wymiary urządzenia i krótki czas badania

Keywords:

płyty włóknisto-cementowe, badania nieniszczące, ultradźwięki

Affiliations:
Dębowski T.-IPPT PAN
Lewandowski M.-IPPT PAN
Mackiewicz S.-IPPT PAN
Ranachowski Z.-IPPT PAN
Schabowicz K.-other affiliation
4.Lewandowski M., Walczak M., Steifer T., Zastosowanie metody pełnej akwizycji macierzy do wizualizacji wad w technice UT Phased-Array, PRZEGLĄD SPAWALNICTWA, ISSN: 0033-2364, Vol.88, No.10, pp.43-45, 2016
Abstract:

Ultradźwiękowe systemy Phased-Array pozwalają na różne tryby skanowania i wizualizacji wad oraz zapewniają wyższą jakość inspekcji niż tradycyjne systemy jednokanałowe. Kolejnym krokiem w rozwoju tych systemów będzie metoda akwizycji pełnej macierzy oraz zaawansowane algorytmy rekonstrukcji obrazów. W artykule przedstawiono zasady działania tych technik oraz wymagania jakie stawiają one przed systemami akwizycji i przetwarzania sygnałów. Zaprezentowano także badawczy system Uniwersalnej Platformy Ultradźwiękowej, który został opracowany specjalnie do testowania i praktycznego wdrażania tych metod. Platforma posłużyła do badań i porównania dwóch metod rekonstrukcji przy wykorzystaniu akwizycji pełnej macierzy – metody STA (Synthetic Transmit Aperture) i metody PWI (Plane Wave Imaging).

Keywords:

UT Phased-Array, akwizycja pełnej macierzy, syntetyczna apertura

Affiliations:
Lewandowski M.-IPPT PAN
Walczak M.-IPPT PAN
Steifer T.-IPPT PAN
5.Nowicki A., Secomski W., Trawiński Z., Lewandowski M., Trots I., Szubielski M., Olszewski R., Estimation of radial artery reactive response using high frequency ultrasound, HYDROACOUSTICS, ISSN: 1642-1817, Vol.19, pp.297-306, 2016
Abstract:

Background:
There is a growing interest in the application of non-invasive clinical tools allowing one to assess the endothelial function, preceding atherosclerosis. The precision in estimating of the artery Flow Mediated Vasodilation (FMD) using standard 10-12 MHz linear array probes does not exceed 0.2 mm, far beyond that required.

Methods:
We have introduced a wide-band, high frequency 25-30 MHz, Golay encoded wobbling type imaging to measure dilation of the radial artery instead of the brachial one. 18 young volunteers, and 4 volunteers with cardiac events history, were examined. In the second approach 20 MHz linear scanning combined with 20 MHz pulsed Doppler attached to the linear array was used. The radial artery FMD was normalized using shear rate at the radial artery wall.

Results and Conclusions:
For the “healthy” group, the FMD resulting from reactive hyperemia response was over 20%; while in the “atherosclerotic” group, the FMD was at least twice as small, not exceeding 10%. The shear rate (SR) normalized FMDSR was in the range from 7.8 to 9.9 in arbitrary units, while in patients with minor cardiac history FMDSR was clearly lower, 6.8 to 7.6. The normalized FMDSR of radial artery RARR can be an alternative to the brachial FMD where the precision of measurements is lower and the diameter dilation does not exceed 7-10%.

Keywords:

thick film transducers, atherosclerosis, flow mediated vasodilation

Affiliations:
Nowicki A.-IPPT PAN
Secomski W.-IPPT PAN
Trawiński Z.-IPPT PAN
Lewandowski M.-IPPT PAN
Trots I.-IPPT PAN
Szubielski M.-other affiliation
Olszewski R.-other affiliation
6.Lipczyńska M., Michałowska I., Werys K., Marczak M., Lewandowski M., Lipiec P., Kasprzak J., Klisiewicz A., Szymański P., Płońska-Gościniak E., Artefakty nieinwazyjnego obrazowania serca, Kardiologia Polska, ISSN: 0022–9032, DOI: 10.5603/kp.2015.0206, Vol.73, pp.60-70, 2015
Abstract:

Nieinwazyjne metody obrazowania serca są nieodłączną częścią współczesnej diagnostyki kardiologicznej. Jakość obrazowania niezależnie od użytej techniki stanowi ważny element interpretacji wyniku. Znajomość najczęstszych artefaktów echokardiografii, tomografii rentgenowskiej (CT, X-ray computed tomography) i badania serca metodą rezonansu magnetycznego (CMRI, cardiac magnetic resonance imaging) oraz sposobu ich uniknięcia jest istotna w codziennej pracy.

Keywords:

obrazowanie medyczne, USG, CT, CMRI

Affiliations:
Lipczyńska M.-other affiliation
Michałowska I.-other affiliation
Werys K.-Warsaw University of Technology (PL)
Marczak M.-other affiliation
Lewandowski M.-IPPT PAN
Lipiec P.-other affiliation
Kasprzak J.-other affiliation
Klisiewicz A.-other affiliation
Szymański P.-other affiliation
Płońska-Gościniak E.-other affiliation
7.Ranachowski Z., Pawełek A., Drzymała P., Bonarski J., Lewandowski M., Ozgowicz W., Light alloys for application as engine parts – comparison of properties of three materials, ZESZYTY NAUKOWE / AKADEMIA MORSKA W SZCZECINIE, ISSN: 1733-8670, Vol.39, No.111, pp.128-132, 2014
Abstract:

This paper discusses the mechanical properties, microstructure and crystallographic texture of light alloys made on the base of aluminium, magnesium and lithium. An acoustic emission (AE) technique was applied to detect the moment of twinning or slip activation during compression and channel – die tests to extend the comprehension on the nature of the plastic deformation processes occurring in the investigated alloy s

Keywords:

hcp metals, aluminium and magnesium alloys, plastic deformation, mechanical twinning, crystallographic texture, acoustic emission

Affiliations:
Ranachowski Z.-IPPT PAN
Pawełek A.-other affiliation
Drzymała P.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Bonarski J.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Lewandowski M.-IPPT PAN
Ozgowicz W.-other affiliation
8.Tasinkevych Y., Klimonda Z., Lewandowski M., Nowicki A., Lewin P.A., Modified multi-element synthetic transmit aperture method for ultrasound imaging: A tissue phantom study, Ultrasonics, ISSN: 0041-624X, DOI: 10.1016/j.ultras.2012.10.001, Vol.53, pp.570-579, 2013
Abstract:

The paper presents the modified multi-element synthetic transmit aperture (MSTA) method for ultrasound imaging. It is based on coherent summation of RF echo signals with apodization weights taking into account the finite size of the transmit subaperture and of the receive element. The work presents extension of the previous study where the modified synthetic transmit aperture (STA) method was considered and verified [1]. In the case of MSTA algorithm the apodization weights were calculated for each imaging point and all combinations of the transmit subaperture and receive element using their angular directivity functions (ADFs). The ADFs were obtained from the exact solution of the corresponding mixed boundary-value problem for periodic baffle system modeling the transducer array. Performance of the developed method was tested using Field II simulated synthetic aperture data of point reflectors for 4 MHz 128-element transducer array with 0.3 mm pitch and 0.02 mm kerf to estimate the visualization depth and lateral resolution. Also experimentally determined data of the tissue-mimicking phantom (Dansk Fantom Service, model 571) obtained using 128 elements, 4 MHz, linear transducer array (model L14-5/38) and Ultrasonix SonixTOUCH Research platform were used for qualitative assessment of imaging contrast improvement. Comparison of the results obtained by the modified and conventional MSTA algorithms indicated 15 dB improvement of the noise reduction in the vicinity of transducer’s surface (1 mm depth), and concurrent increase in the visualization depth (86% augment of the scattered amplitude at the depth of 90 mm). However, this increase was achieved at the expense of minor degradation of the lateral resolution of approximately 8% at the depth of 50 mm and 5% at the depth of 90 mm.

Keywords:

Synthetic aperture imaging, Ultrasound imaging, Directivity function, Beamforming

Affiliations:
Tasinkevych Y.-IPPT PAN
Klimonda Z.-IPPT PAN
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
Lewin P.A.-Drexel University (US)
9.Gawlikowski M., Lewandowski M., Nowicki A., Kustosz R., Walczak M., Karwat P., Karłowicz P., The Application of Ultrasonic Methods to Flow Measurement and Detection of Microembolus in Heart Prostheses, ACTA PHYSICA POLONICA A, ISSN: 0587-4246, DOI: 10.12693/APhysPolA.124.417, Vol.124, No.3, pp.417-420, 2013
Abstract:

For the last 20 years the world cardiosurgery has presented a considerable change of attitude to mechanical circulatory support. In spite of technological progress the main problems in ventricular assist devices are: thrombosis and low accuracy of flow measurements. In this paper the prototype of multi-gate Doppler flowmeter intended for cardiac assist system ReligaHeart EXT has been presented as well as the possibility of ultrasonic micro embolus detection.

Keywords:

artificial heart, microemboli, ultrasound Doppler

Affiliations:
Gawlikowski M.-other affiliation
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
Kustosz R.-other affiliation
Walczak M.-IPPT PAN
Karwat P.-IPPT PAN
Karłowicz P.-other affiliation
10.Ranachowski Z., Pawełek A., Jasieński Z., Piątkowski A., Kúdela Jr. S., Lewandowski M., Mazuruk P., Durability and wear of engine parts – new methods of testing of alloys and composites, ZESZYTY NAUKOWE / AKADEMIA MORSKA W SZCZECINIE, ISSN: 1733-8670, Vol.35, No.107, pp.125-131, 2013
Abstract:

The paper deals with the problems related to the diagnostics of selected parts of modern Diesel engines. The evolution of mechanical properties of four alloys of Mg-Li-Al system and four composites made on the base of the alloys mentioned above, caused by variation of its composition was presented. The Acoustic Emission (AE) method applied to monitoring of degradation of mechanical properties of the alloys and composites was described. Moreover, the results of the investigation of failures occurring in the injectors of Common Rail Diesel engines per formed with the application of AE method were also reported.

Keywords:

Diesel engines diagnostics, light alloys and composites, Common Rail fuel system, Acoustic Emission method

Affiliations:
Ranachowski Z.-IPPT PAN
Pawełek A.-other affiliation
Jasieński Z.-other affiliation
Piątkowski A.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Kúdela Jr. S.-Institute of Materials and Machine Mechanics, Slovak Academy of Sciences (SK)
Lewandowski M.-IPPT PAN
Mazuruk P.-other affiliation
11.Mlosek K., Malinowska S., Dębowska R., Lewandowski M., Nowicki A., The High Frequency (HF) Ultrasound as a Useful Imaging Technique for the Efficacy Assessment of Different Anti-Cellulite Treatments, Journal of Cosmetics, Dermatological Sciences and Applications, ISSN: 2161-4105, DOI: 10.4236/jcdsa.2013.31A013, Vol.3, pp.90-98, 2013
Abstract:

The purpose of the research was to evaluate the role of high frequency ultrasound in monitoring and efficacy assessment of anti-cellulite treatments. A group of 66 women used 3 different types of anti-cellulite treatments; additionally a placebo group (n = 18) was created. The μ-Scan ultrasound device with a 35 MHz mechanical probe was used for the examinations. The following parameters were subjected to the ultrasound evaluation: epidermis thickness, dermis thickness, dermis echogenicity, the length and area of subcutaneous tissue bands projecting into the dermis (dermis-hypodermis junction), as well as the presence/absence of edema within the dermis. As a result of anti-cellulite treatment, the length and area of dermis-hypodermis junction significantly decreased, and dermis echogenicity significantly increased. Ultrasound imaging made it possible to evaluate the efficacy of the applied treatments. The high frequency ultrasound is a useful imaging technique for the application in aesthetic dermatology and cosmetology.

Keywords:

Aesthetic Medicine, Cellulite, Anti-Cellulite Treatment, High Frequency Ultrasound, Skin Ultrasound

Affiliations:
Mlosek K.-Medical University of Warsaw (PL)
Malinowska S.-Life-Beauty (PL)
Dębowska R.-Dr. Irena Eris Scientific Research Center (PL)
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
12.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: 0885-3010, DOI: 10.1109/TUFFC.2012.2347, Vol.59, No.7, pp.1470-1477, 2012
Abstract:

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 encoder-digitizer module executing all of the transmission and reception functions is based on a single low-cost field programmable gate array (FPGA). The scanner is equipped with a mechanical sector-scan 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.

Keywords:

cancellous bone, broadband ultrasound attenuation, FPGA

Affiliations:
Litniewski J.-IPPT PAN
Cieślik L.-IPPT PAN
Lewandowski M.-IPPT PAN
Tymkiewicz R.-IPPT PAN
Zienkiewicz B.-IPPT PAN
Nowicki A.-IPPT PAN
13.Mlosek K., Woźniak W., Malinowska S., Lewandowski M., Nowicki A., The effectiveness of anticellulite treatment using tripolar radiofrequency monitored by classic and high-frequency ultrasound, JOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY AND VENEREOLOGY, ISSN: 0926-9959, DOI: 10.1111/j.1468-3083.2011.04148.x, Vol.26, pp.696-703, 2012
Abstract:

Background
Cellulite affects nearly 85% of the female population. Given the size of the phenomenon, we are continuously looking for effective ways to reduce cellulite. Reliable monitoring of anticellulite treatment remains a problem.

Objective
The main aim of the study was to evaluate the effectiveness of anticellulite treatment carried out using radiofrequency (RF), which was monitored by classical and high-frequency ultrasound.

Methods
Twenty-eight women underwent anticellulite treatment using RF, 17 women were in the placebo group. The therapy was monitored by classical and high-frequency ultrasound. The examinations evaluated the thickness of the epidermal echo, dermis thickness, dermis echogenicity, the length of the subcutaneous tissue bands growing into the dermis, the presence or absence of oedema, the thickness of subcutaneous tissue as well as thigh circumference and the stage of cellulite (according to the Nurnberger–Muller scale).

Results
Cellulite was reduced in 89.286% of the women who underwent RF treatment. After the therapy, the following observations were made: a decrease in the thickness of the dermis and subcutaneous tissue, an increase in echogenicity reflecting on the increase in the number of collagen fibres, decreased subcutaneous tissue growing into bands in the dermis, and the reduction of oedema. In the placebo group, no statistically significant changes of the above parameters were observed.

Conclusion
Radiofrequency enables cellulite reduction. A crucial aspect is proper monitoring of the progress of such therapy, which ultrasound allows.

Keywords:

anticellulite treatment, high-frequency ultrasound

Affiliations:
Mlosek K.-Medical University of Warsaw (PL)
Woźniak W.-other affiliation
Malinowska S.-Life-Beauty (PL)
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
14.Tasinkevych Y., Trots I., Nowicki A., Lewandowski M., Optimization of the Multi-element Synthetic Transmit Aperture Method for Medical Ultrasound Imaging Applications, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.37, No.1, pp.47-55, 2012
Abstract:

The paper presents the optimization problem for the multi-element synthetic transmit aperture method (MSTA) in ultrasound imaging applications. The optimal choice of the transmit aperture size is made as a trade-off between the lateral resolution, penetration depth and the frame rate. Results of the analysis obtained by a developed optimization algorithm are presented. The maximum penetration depth and lateral resolution at given depths are chosen as optimization criteria. The results of numerical experiments carried out in MATLAB using synthetic aperture data of point reflectors obtained by the FIELD II simulation program are presented. The visualization of experimental synthetic aperture data of a tissue mimicking phantom and in vitro measurements of the beef liver performed using the SonixTOUCH Research system are also shown.

Keywords:

ultrasound imaging, synthetic aperture, beamforming

Affiliations:
Tasinkevych Y.-IPPT PAN
Trots I.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
15.Lewandowski M., Nowa architektura i możliwości przetwarzania sygnałów w systemach defektoskopowych, PRZEGLĄD SPAWALNICTWA, ISSN: 0033-2364, Vol.13, pp.19-23, 2012
Abstract:

Prowadzone w IPPT PAN prace mające na celu opracowanie uniwersalnych wielokanałowych systemów ultradźwiękowych do zastosowań medycznych i przemysłowych zaowocowały zaproponowaniem nowych architektur komunikacji i przetwarzania cyfrowego sygnałów w oparciu o procesory wielordzeniowe oraz procesory graficzne (GPU). Opracowana architektura systemów jest skalowalna ze względu na liczbę kanałów i może być zastosowana do systemów jedno- i wielokanałowych. W artykule przedstawiono funkcje i metody realizacji przetwarzania w defektoskopach z analogowym i cyfrowym torem przetwarzania sygnałów. Wskazano na ograniczenia obecnych systemów oraz przedstawiono nową architekturę, która pozwala na pełną programowalność toru przetwarzania. Pokazano przykładowe metody i algorytmy przetwarzania, których implementacja może przyczynić się do znacznego zwiększenia funkcjonalności urządzeń defektoskopowych zbudowanych w oparciu o nową architekturę.

Keywords:

defektoskopia ultradźwiękowa, przetwarzanie sygnałów, procesory GPU

Affiliations:
Lewandowski M.-IPPT PAN
16.Wójcik J., Trots I., Lewandowski M., Nowicki A., Cumulative Method of the Image Reconstruction in Synthetic Aperture. Experimental Results, HYDROACOUSTICS, ISSN: 1642-1817, Vol.15, pp.195-206, 2012
Abstract:

An analytical model of imaging using synthetic aperture (SA) methods is presented. This model takes into account: fundamental features of an environment, of an electric transmission/reception path and a description of SA structure - possible schemes of transmission, reception and image formation. Then two schemes are analyzed: a proposed cumulative synthetic transmit aperture (CSTA) and for comparison of the standard STA schemes. For both methods identical basic parameters - equal sequences of transmit and receive transducers were applied. The distinctive feature of CSTA is gathering (summing up) echoes of subsequent transmissions in one acquisition mat ix sufficient for image reconstruction. In traditionally applied STA methods a separate acquisition matrix for each transmission is created. Therefore there are a dozen to several dozen more matrices and the time of image reconstruction is at least several times longer than in CSTA. The presented experimental results obtained using wire and tissue mimicking phantoms have shown the comparable imaging quality in both methods.

Keywords:

ultrasound imaging, synthetic aperture

Affiliations:
Wójcik J.-IPPT PAN
Trots I.-IPPT PAN
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
17.Tasinkevych Y., Trots I., Nowicki A., Lewandowski M., Transmit Sub-aperture Optimization in MSTA Ultrasound Imaging Method, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.65, pp.422-427, 2012
Abstract:

The paper presents the optimization problem for the multi-element synthetic transmit aperture method (MSTA) in ultrasound imaging applications. The optimal choice of the transmit aperture size is performed as a trade-off between the lateral resolution, penetration depth and the frame rate. Results of the analysis obtained by a developed optimization algorithm are presented. Maximum penetration depth and the best lateral resolution at given depths are chosen as the optimization criteria. The optimization algorithm was tested using synthetic aperture data of point reflectors simulated by Filed II program for Matlab® for the case of 5MHz 128-element linear transducer array with 0.48 mm pitch are presented. The visualization of experimentally obtained synthetic aperture data of a tissue mimicking phantom and in vitro measurements of the beef liver are also shown. The data were obtained using the SonixTOUCH Research systemequipped with a linear 4MHz 128 element transducerwith 0.3 mm element pitch, 0.28 mm element width and 70% fractional bandwidth was excited by one sine cycle pulse burst of transducer's center frequency.

Keywords:

synthetic aperture method, ultrasound imaging, beamforming

Affiliations:
Tasinkevych Y.-IPPT PAN
Trots I.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
18.Trots I., Tasinkevych Y., Nowicki A., Lewandowski M., Coded Transmission in Synthetic Transmit Aperture Ultrasound Imaging Method, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.63, pp.331-336, 2012
Abstract:

The paper presents the study of synthetic transmit aperture method applying the Golay coded transmission for medical ultrasound imaging. Longer coded excitation allows to increase the total energy of the transmitted signal without increasing the peak pressure. Signal-to-noise ratio and penetration depth are improved maintaining high ultrasound image resolution. In the work the 128-element linear transducer array with 0.3 mm inter-element spacing excited by one cycle and the 8 and 16-bit Golay coded sequences at nominal frequencies 4 MHz was used. Single element transmission aperture was used to generate a spherical wave covering the full image region and all the elements received the echo signals. The comparison of 2D ultrasound image s of the wire phantom as well as of the tissue mimicking phantom is presented to demonstrate the benefits of the coded transmission. The results were obtained using the synthetic aperture algorithm with transmit and receive signals correction based on a single element directivity function

Keywords:

Golay coded sequences, radiation pattern, synthetic aperture, ultrasound imaging

Affiliations:
Trots I.-IPPT PAN
Tasinkevych Y.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
19.Trots I., Tasinkevych Y., Nowicki A., Lewandowski M., In Vitro Study of Coded Transmission in Synthetic Aperture Ultrasound Imaging Systems, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.6, No.6, pp.82-87, 2012
Abstract:

In the paper the study of synthetic transmit aperture method applying the Golay coded transmission for medical ultrasound imaging is presented. Longer coded excitation allows to increase the total energy of the transmitted signal without increasing the peak pressure. Moreover signal-to-noise ratio and penetration depth are improved while maintaining high ultrasound image resolution. In the work the 128-element linear transducer array with 0.3 mm inter-element spacing excited by one cycle and the 8 and 16- bit Golay coded sequences at nominal frequency 4 MHz was used. To generate a spherical wave covering the full image region a single element transmission aperture was used and all the elements received the echo signals. The comparison of 2D ultrasound images of the tissue mimicking phantom and in vitro measurements of the beef liver is presented to illustrate the benefits of the coded transmission. The results were obtained using the synthetic aperture algorithm with transmit and receive signals correction based on a single element directivity function.

Keywords:

Golay coded sequences, radiation pattern, signal, processing, synthetic aperture, ultrasound imaging

Affiliations:
Trots I.-IPPT PAN
Tasinkevych Y.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
20.Mlosek K., Dębowska R.M., Lewandowski M., Malinowska S., Nowicki A., Eris I., Imaging of the skin and subcutaneous tissue using classical and high-frequency ultrasonographies in anti-cellulite therapy, SKIN RESEARCH AND TECHNOLOGY, ISSN: 0909-752X, Vol.17, pp.461-468, 2011
Abstract:

Background: The development of ultrasonography allowed for skin imaging used in dermatology and esthetic medicine. By means of classic and high-frequency ultrasonographies, changes within the dermis and subcutaneous tissue can be presented.
Objective: The aim of this study was to show the possibi­lities of applying classic and high-frequency ultrasonogra­phies in esthetic dermatology based on monitoring various types of anti-cellulite therapies.
Methods: Sixty-one women with cellulite were assigned to two smaller groups. One group was using anti-cellulite cream and the second group was a placebo group. The ultrasound examin;ition was carried out before the initiation and after the completion of the treatment and evaluated epidermal echoes, the thickness of the subcutaneous tissue and the dermis, dermis echogenicity, the length and surface rea of the subcutaneous tissue fascicles growing into the dermis, and the presence or absence of edemas.
Results: After the completion of the treatment, a statistically significant difference was observed. The most useful para­meters were as follows: the thickness of the subcutaneous tissue, echogenicity, the surface area and length of the sub­cutaneous tissue, as well as the presence of edemas. The discussed changes were not observed in the placebo group.
Conclusion: Classic and high-frequency ultrasonographies are useful methods for monitoring anti-cellulite therapies.

Keywords:

high-frequency ultrasonography - cellulite classic ultrasonography ultrasonography

Affiliations:
Mlosek K.-Medical University of Warsaw (PL)
Dębowska R.M.-Dr. Irena Eris Scientific Research Center (PL)
Lewandowski M.-IPPT PAN
Malinowska S.-Life-Beauty (PL)
Nowicki A.-IPPT PAN
Eris I.-Scientific Research Center Dr Irena Eris (PL)
21.Nowicki A., Lewandowski M., Wójcik J., Tymkiewicz R., Lou-Moller R., Wolny W., Zawada T., Thick Film Transducers for High Frequency Coded Ultrasonography, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.36, No.4, pp.945-954, 2011
Abstract:

Recently a new technology of piezoelectric transducers based on PZT thick film has been developed as a response to a call for devices working at higher frequencies suitable for production in large numbers at low cost. Eight PZT thick film based focused transducers with resonant frequency close to 40 MHz were fabricated and experimentally investigated. The PZT thick films were deposited on acoustically engineered ceramic substrates by pad printing. Considering high frequency and nonlinear propagation it has been decided to evaluate the axial pressure field emitted (and reflected by thick metal plate) by each of concave transducer differing in radius of curvature – 11 mm, 12 mm, 15 mm, 16 mm.
All transducers were activated using AVTEC AVG-3A-PS transmitter and Ritec diplexer connected directly to Agilent 54641D oscilloscope. As anticipated, in all cases the focal distance was up to 10% closer to the transducer face than the one related to the curvature radius. Axial pressure distributions were also compared to the calculated ones (with the experimentally determined boundary conditions) using the angular spectrum method including nonlinear propagation in water. The computed results are in a very good agreement with the experimental ones. The transducers were excited with Golay coded sequences at 35–40 MHz. Introducing the coded excitation allowed replacing the short-burst transmission at 20 MHz with the same peak amplitude pressure, but with almost double center frequency, resulting in considerably better axial resolution. The thick films exhibited at least 30% bandwidth broadening comparing to the standard PZ 27 transducer, resulting in an increase in matching filtering output by a factor of 1.4–1.5 and finally resulting in a SNR gain of the same order.

Keywords:

transducers, thick film, high frequency ultrasound, pulse compression, Golay codes

Affiliations:
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
Wójcik J.-IPPT PAN
Tymkiewicz R.-IPPT PAN
Lou-Moller R.-InSensor A/S (DK)
Wolny W.-InSensor A/S (DK)
Zawada T.-Ferroperm Piezoceramics A/S (DK)
22.Trots I., Tasinkevych Y., Nowicki A., Lewandowski M., Golay Coded Sequences in Synthetic Aperture Imaging Systems, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.36, No.4, pp.913-926, 2011
Abstract:

The paper presents the theoretical and experimental study of synthetic transmit aperture (STA) method combined with Golay coded transmission for medical ultrasound imaging applications. The transmission of long waveforms characterized by a particular autocorrelation function allows to increase the total energy of the transmitted signal without increasing the peak pressure. It can also improve signal-to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution.
In the work the 128-element linear transducer array with 0.3 mm pitch excited by the 8 and 16-bits Golay coded sequences as well as a one cycle at nominal frequencies 4 MHz were used. The comparison of 2D ultrasound images of the tissue mimicking phantoms is presented to demonstrate the benefits of coded transmission. The image reconstruction was performed using synthetic STA algorithm with transmit and receive signals correction based on a single element directivity function.

Keywords:

ultrasound imaging, synthetic aperture, beamforming, radiation pattern, coded sequences, Golay codes

Affiliations:
Trots I.-IPPT PAN
Tasinkevych Y.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
23.Lewandowski M., Klimonda Z., Obrazowanie ultradźwiękowe wad za pomocą metod syntetycznej apertury, PRZEGLĄD SPAWALNICTWA, ISSN: 0033-2364, Vol.13, pp.29-32, 2011
Abstract:

Ultradźwiękowe metody badań nieniszczących przechodzą obecnie metamorfozę od systemów z głowicami jednoelementowymi do systemów wielokanałowych z głowicami fazowymi (PA Phased Array). Prowadzony obecnie w Zakładzie Ultradźwięków IPPT PAN projekt ma na celu opracowanie uniwersalnej wielokanałowej platformy ultradźwiękowej oraz metod rekonstrukcji obrazów mogących znaleźć zastosowanie zarówno w medycynie, jak i w badaniach nieniszczących. Przeprowadzono wstępne badania mające na celu porównanie różnych metod rekonstrukcji obrazów wad w trybie B-mode. W tym celu dokonano akwizycji ech ultradźwiękowych od wad w szynie kolejowej przy pomocy ultrasonografu badawczego wyposażonego w 128-elementową głowicą fazową o częstotliwości 4 MHz. Uzyskane sygnały ech wysokiej częstotliwości poddano następnie obróbce cyfrowej w celu uzyskania obrazu B-mode. Zastosowano i porównano różne metody rekonstrukcji obrazu: klasyczny beamforming oraz metodę syntetycznej apertury. Wstępne wyniki wskazują na wysoką jakość rekonstrukcji metodą syntetycznej apertury, która zapewnia równomierną rozdzielczość poprzeczną w całej głębokości obrazowania. Zastosowanie alternatywnych schematów nadawczo-odbiorczych w metodzie syntetycznej apertury umożliwia dodatkowo optymalizację metody pod względem prędkości badania lub jakości obrazowania. Wyniki te potwierdzają przydatność i konkurencyjność metody syntetycznej apertury do stosowanej obecnie metody beamformingu.

Keywords:

ultradźwiękowe badania nieniszczące, głowice Phased-Array, metody syntetycznej apertury

Affiliations:
Lewandowski M.-IPPT PAN
Klimonda Z.-IPPT PAN
24.Trots I., Tasinkevych Y, Nowicki A., Lewandowski M., Multi-Element Synthetic Transmit Aperture Method in Medical Ultrasound Imaging, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.80, pp.562-567, 2011
Abstract:

The paper presents the multi-element synthetic transmit aperture (MSTA) method with a small number of elements transmitting and all elements receiving apertures in medical ultrasound imaging. Compared to other methods the MSTA allows to increase the system frame rate and provides the best compromise between penetration depth and lateral resolution.
In the experiments a 128-element linear transducer array with 0.3 mm inter-element spacing and a burst pulse of 125 ns duration were used. The comparison of 2D ultrasound images of tissue mimicking phantom obtained using the STA and the MSTA methods is presented to demonstrate the benefits of the second method. The obtained results were performed using SA algorithm with transmit and receive signals correction based on a single element directivity function.

Keywords:

beamforming, frame rate, synthetic aperture, ultrasound imaging

Affiliations:
Trots I.-IPPT PAN
Tasinkevych Y-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
25.Karwat P., Klimonda Z., Seklewski M., Lewandowski M., Nowicki A., Data reduction method for synthetic transmit aperture algorithm, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.35, No.4, pp.635-642, 2010
Abstract:

Ultrasonic methods of human body internal structures imaging are being continuously enhanced. New algorithms are created to improve certain output parameters. A synthetic aperture method (SA) is an example which allows to display images at higher frame-rate than in case of conventional beam-forming method. Higher computational complexity is a limitation of SA method and it can prevent from obtaining a desired reconstruction time. This problem can be solved by neglecting a part of data. Obviously it implies a decrease of imaging quality, however a proper data reduction technique would minimize the image degradation. A proposed way of data reduction can be used with synthetic transmit aperture method (STA) and it bases on an assumption that a signal obtained from any pair of transducers is the same, no matter which transducer transmits and which receives. According to this postulate, nearly a half of the data can be ignored without image quality decrease. The presented results of simulations and measurements with use of wire and tissue phantom prove that the proposed data reduction technique reduces the amount of data to be processed by half, while maintaining resolution and allowing only a small decrease of SNR and contrast of resulting images.

Keywords:

ultrasonic imaging, synthetic transmit aperture, data reduction, effective aperture, reciprocity

Affiliations:
Karwat P.-IPPT PAN
Klimonda Z.-IPPT PAN
Seklewski M.-other affiliation
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
26.Secomski W., Nowicki A., Wójcik J., Lewandowski M., Walczak M., Tymkiewicz R., Annular array transducer and matched amplifier for therapeutic ultrasound, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, DOI: 10.2478/v10168-010-0049-6, Vol.35, No.4, pp.653-660, 2010
Abstract:

The use of therapeutic ultrasound continues to grow. A focused ultrasonic wave can increase the tissue temperature locally for the non-invasive cancer treatment or other medical applications. The authors have designed a seven-element annular array transducer operating at 2.4 MHz. Each element was excited by sine burst supplied by a linear amplifier and FPGA control circuits. The acoustic field, generated by a transducer was initially numerically simulated in a computer and next compared to water tank hydrophone measurements performed at 20, 40 and 60 mm focal depth. The results showed good agreement of the measurements with theory and the possibility to focus the ultrasound in the preselected area. The total acoustic power radiated by the annular array was equal to 2.4W.

Keywords:

ultrasonic therapy, annular array transducer, ultrasonic field

Affiliations:
Secomski W.-IPPT PAN
Nowicki A.-IPPT PAN
Wójcik J.-IPPT PAN
Lewandowski M.-IPPT PAN
Walczak M.-IPPT PAN
Tymkiewicz R.-IPPT PAN
27.Trots I., Nowicki A., Lewandowski M., Tasinkevych Y., Multi-element synthetic transmit aperture in medical ultrasound imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.35, No.4, pp.687-699, 2010
Abstract:

Synthetic aperture (SA) technique is a novel approach to present day commercial systems and has previously not been used in medical ultrasound imaging. The basic idea of SA is to combine information acquired simultaneously from all directions over a number of emissions and to reconstruct the full image from these data. The paper presents the multi-element STA (MSTA) method for medical ultrasound imaging. The main difference with the STA approach is the use of a few elements in the transmit mode in contrast to a single element aperture. This allows increasing the system frame rate, decreasing the number of emissions, and provides the best compromise between the penetration depth and lateral resolution. Besides, a modified MSTA is proposed with a corresponding RF signal correction in the receive mode, which accounts for the element directivity property. In the experiments a 32-element linear transducer array with 0.48 mm interelement spacing and a burst pulse of 100 ns duration were used. Two elements wide transmission aperture was used to generate an ultrasound wave covering the full image region. The comparison of 2D ultrasound images of a tissue mimicking phantom obtained using the STA and MSTA methods is presented to demonstrate the benefits of the second one.

Keywords:

ultrasound imaging, synthetic aperture, beamforming

Affiliations:
Trots I.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
Tasinkevych Y.-IPPT PAN
28.Sęklewski M., Karwat P., Klimonda Z., Lewandowski M., Nowicki A., Preliminary results: comparison of different schemes of synthetic aperture technique in ultrasonic imaging, HYDROACOUSTICS, ISSN: 1642-1817, Vol.13, pp.243-252, 2010
Abstract:

The Synthetic Aperture (SA) methods are widespread and successfully used in radar technology, as well as in the sonar systems. The advantages of high framerate and its relatively good resolution in the whole area of scanning, make this technique an object of interest in medical imaging methods such as ultrasonography (US). This paper describes the possible usage of the SA method in ultrasound imaging. The introduction to the principles of the SA technique in ultrasonography is presented. The measurements of different SA schemes were conducted using the set-up consisting of the research ultrasonograph module, the PC and the special wire phantom. The results for different schemes of image reconstruction are presented. Particularly the Synthetic Transmit Aperture (STA) technique was concerned. Results of the STA method are discussed in this paper.

Keywords:

synthetic aperture focusing technique, ultrasonic imaging

Affiliations:
Sęklewski M.-IPPT PAN
Karwat P.-IPPT PAN
Klimonda Z.-IPPT PAN
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
29.Piotrzkowska H., Litniewski J., Szymańska E., Lewandowski M., Nowicki A., Statistics of envelope of high frequency ultrasound signal backscattered in human dermis, HYDROACOUSTICS, ISSN: 1642-1817, Vol.13, pp.205-214, 2010
Abstract:

The scattering of ultrasonic waves depends on the size, shape, acoustical properties and concentration of scatterers in tissue. In these study K distribution of the ultrasound backscatter envelope was used to assess the structural properties of the skin tissue. The custom-designed high frequency ultrasonic scanner was applied to obtain RF B-scans of the skin in vivo at the frequency of 20-30MHz.
The results are encouraging. The K distribution models the envelope statistics very well. The parameters of the K-distribution, namely, the effective number of scatterers may be useful for the skin characterization.

Keywords:

skin characterization, ultrasound, K distribution

Affiliations:
Piotrzkowska H.-IPPT PAN
Litniewski J.-IPPT PAN
Szymańska E.-other affiliation
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
30.Cieślik L., Litniewski J., Lewandowski M., Nowicki A., Evaluation of trabecular bone properties using ultrasonic scanner, HYDROACOUSTICS, ISSN: 1642-1817, Vol.13, pp.39-52, 2010
Abstract:

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.

Keywords:

bone structure, bone properties, calcaneus

Affiliations:
Cieślik L.-IPPT PAN
Litniewski J.-IPPT PAN
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
31.Trots I., Nowicki A., Lewandowski M., Synthetic transmit aperture method in medical ultrasonic imaging, World Academy of Science, Engineering and Technology, ISSN: 2010-376X, Vol.64, pp.202-205, 2010
Abstract:

The work describes the use of a synthetic transmit aperture (STA) with a single element transmitting and all elements receiving in medical ultrasound imaging. STA technique is a novel approach to today’s commercial systems, where an image is acquired sequentially one image line at a time that puts a strict limit on the frame rate and the amount of data needed for high image quality. The STA imaging allows to acquire data simultaneously from all directions over a number of emissions, and the full image can be reconstructed.
In experiments a 32-element linear transducer array with 0.48 mm inter-element spacing was used. Single element transmission aperture was used to generate a spherical wave covering the full image region. The 2D ultrasound images of wire phantom are presented obtained using the STA and commercial ultrasound scanner Antares to demonstrate the benefits of the SA imaging.

Keywords:

ultrasound imaging, synthetic aperture, frame rate, beamforming

Affiliations:
Trots I.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
32.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: 0137-5075, Vol.34, No.4, pp.471-480, 2009
Abstract:

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 non-invasively the structural and mechanical properties of tissue. We intend to apply the custom-designed high-frequency 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 B-scans 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.

Keywords:

attenuation coefficient, backscattering coefficient, dermis

Affiliations:
Piotrzkowska H.-IPPT PAN
Litniewski J.-IPPT PAN
Lewandowski M.-IPPT PAN
Szymańska E.-other affiliation
Nowicki A.-IPPT PAN
33.Karwat P., Nowicki A., Lewandowski M., Blood scattering model for pulsed doppler, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.34, No.4, pp.677-685, 2009
Abstract:

The subject of this paper is a new software simulating ultrasound signal scattered on moving blood cells during Doppler examination of blood flow velocity using pulsed technique. Generated data are used for optimization and validation of Doppler signals processing algorithms.
The algorithm is based on the finite elements method FEM. A rigorous set of postulates which simplifies physics of modeled phenomenon enables to quicken the program significantly while preserving important properties (from application point of view) of generated signal.
The paper includes description of Doppler RF signal generation algorithm. The simplifying postulates are listed together with resulting signal fidelity degradation. Finally generated raw data is presented together with its Doppler Audio and Color processed version.
The signal processing results enable to reconstruct correctly the velocity profile and its time dependence. The results clearly confirm that the data generated by the algorithm are suitable for Doppler signals processing.

Keywords:

RF signal simulation, scattering on blood cells, pulsed Doppler

Affiliations:
Karwat P.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
34.Trots I., Nowicki A., Lewandowski M., Synthetic transmit aperture in ultrasound imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.34, No.4, pp.685-695, 2009
Abstract:

The paper describes the use of synthetic transmit aperture (STA) imaging in medical ultrasound. The synthetic aperture (SA) imaging is a novel approach to today's commercial systems. In these systems the image is acquired sequentially one image line at a time that puts a strict limit on the frame rate and the possibility of acquiring a sufficient amount of data for high image quality. This limitation can be lifted by employing SA imaging where the data are acquired simultaneously from all directions over a number of emissions, and the full image can be reconstructed from those data. Due to the complete data set, it is possible to have full transmitting and receiving focusing at the entire image region to improve the contrast dynamic and spatial resolution. The paper describes the STA imaging with a single element transmitting and all elements receiving apertures. In experiments, 32-element linear transducer array with 0.48 mm inter-element spacing and a burst pulse of 100ns duration were used. The single element transmission aperture was used to generate a spherical wave covering the full image region. The 2D ultrasound images of wire phantom are presented to demonstrate the benefits of SA imaging.

Keywords:

ultrasound imaging, synthetic aperture, beamforming

Affiliations:
Trots I.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
35.Lewandowski M., Nowicki A., High frequency coded imaging system with RF software signal processing, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, ISSN: 0885-3010, DOI: 10.1109/TUFFC.2008.871, Vol.55, No.8, pp.1878-1882, 2008
Abstract:

Coded transmission is an approach to solve the inherent compromise between penetration and resolution required in ultrasound imaging. Our goal was to examine the applicability of the coded excitation to HF (20–35MHz) ultrasound imaging. A novel real-time imaging system for research and evaluation of the coded transmission was developed. The digital programmable coder-digitizer module based on the field programmable gate array (FPGA) chip supports arbitrary waveform coded transmission and RF echoes sampling up to 200MSPS, as well as real-time streaming of digitized RF data via a high speed USB interface to the PC. All RF and image data processing was implemented in the software. A novel balanced software architecture supports real-time processing and display at rates up to 30 frames/sec. The system was used to acquire quantitative data for sine burst and 16-bit Golay code excitation at 20MHz fundamental frequency. SNR gain close to 14 dB was obtained. The example of the skin scan clearly shows the extended penetration and improved contrast when 35MHz Golay code is used. The presented system is a practical and low cost implementation of coded excitation technique in HF ultrasound imaging that can be used as a research tool as well as to be introduced into production.

Keywords:

high frequency ultrasound, coded transmission, pulse compression, RF signal processing

Affiliations:
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
36.Trots I., Nowicki A., Lewandowski M., Laboratory setup for synthetic aperture ultrasound imaging, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.33, No.4, pp.573-580, 2008
Abstract:

The paper describes the synthetic transmit aperture (STA) imaging system with a single element transmitting and multi-element reception in medical ultrasound. Synthetic aperture method allows to achieve high electronic signal-to-noise ratio and good contrast resolution. A laboratory setup for acquisition of RF signals from linear transducer array was built. Simulated multichannel acquisition by multiplexing individual transducer was performed. In experiments 32-element linear transducer array with 0.48 mm inter-element spacing and a burst pulse with time duration 100 ns was used. Single element in the transducer transmitting aperture was used to generate a spherical wave covering the full image region. The echo signals were sampled independently by individual elements for each transmission. The comparison of 2D ultrasound images of wire phantom obtained using STA method and standard linear array scanning with commercial ultrasonograph is given. The results show excellent image resolution of the STA method and its robustness to refraction, attenuation and multiple reflection of ultrasound waves.

Keywords:

ultrasound imaging, synthetic aperture, contrast resolution

Affiliations:
Trots I.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
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: 0137-5075, Vol.33, No.4, pp.593-601, 2008
Abstract:

This study investigates a new composing method of double transmission of short coded sequences based on well-known Golay complementary codes, which allow to obtain the higher signal-to-noise 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 64-bits pair of Golay sequences and combined sequences consisting of two 8-, 16-, and 32-bits 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.

Keywords:

Golay complementary sequences, double pulse transmission, dead zone

Affiliations:
Trots I.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
Secomski W.-IPPT PAN
Litniewski J.-IPPT PAN
38.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: 1642-1817, Vol.11, pp.419-430, 2008
Abstract:

An influence effect of fractional bandwidth of ultrasound imaging transducer on the gain of compressed echo signal being the complementary Golay sequences (CGS) with different spectral widths is studied in this paper. Also, a new composing transmission method of CGS is discussed together with compression technique applied in order to increase the signal-to-noise ratio (SNR) and penetration.
The CGS with two different bit lengths, one-cycle and two-cycles are investigated. Two transducers with fractional bandwidth of 25% and 80% at centre frequency 6 MHz are used. The experimental results are presented, clearly proofing that increasing of the code length leads to compressed echo amplitude enhancement. The smaller the bandwidth is the larger is this effect; the pulse-echo sensitivity of the echo amplitude increases by 1.88 for 25% fractional bandwidth and 1.47 for 80% while preserving time resolution. The presented results of double transmission of short codes show the penetration and SNR improvement while maintaining dead zone.

Keywords:

ultrasound, transducer, bandwidth, Golay code

Affiliations:
Trots I.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
Secomski W.-IPPT PAN
Litniewski J.-IPPT PAN
39.Litniewski J., Nowicki A., Klimonda Z., Lewandowski M., Sound fields for coded excitations in water and tissue, ULTRASOUND IN MEDICINE AND BIOLOGY, ISSN: 0301-5629, Vol.33, No.4, pp.601-607, 2007
Abstract:

Coded ultrasonography is intensively studied in many laboratories due to its remarkable properties, particularly increased penetration depth and signal-to-noise 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 13-bits Barker code and 16-bits Golay complementary codes. The results of measured pressure field distributions before and after compression were compared with those recorded using short pulse excitation.

Keywords:

Coded excitation, Ultrasound field distribution, Matching filtering

Affiliations:
Litniewski J.-IPPT PAN
Nowicki A.-IPPT PAN
Klimonda Z.-IPPT PAN
Lewandowski M.-IPPT PAN
40.Lewandowski M., Nowicki A., Universal coded ultrasound imaging system with software processing, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.32, No.4, pp.81-86, 2007
Abstract:

Coded transmission is a technique to solve the inherent compromise between penetration and resolution required in ultrasound imaging. Our aim was to examine the performance of the coded excitation in HF (20–35 MHz) ultrasound imaging. For this purpose a novel realtime imaging system has been developed. The digital programmable coder-digitizer module supports arbitrary coded waveform generation and RF echoes sampling up to 200 MSPS. All digital RF and image processing was implemented in software. The system performance was evaluated with a single thick-film transducer (focused 25 MHz, 75% bandwidth) scanning head. The RF echoes were acquired from a perfect reflector located with 1 cm of tissue mimicking material. Single sinus burst and 16-bits Golay codes excitations were evaluated. SNR gain for the Golay codes (referenced to single burst) of 15 dB for 20 MHz and 16 dB for 35 MHz were obtained. The axial resolution measured at half maximum was 35 ns for 20 MHz and 25 ns for 35 MHz for both single burst and the Golay codes. It clearly shows that the Golay codes can perfectly restore the resolution while giving respectable SNR gain.

Keywords:

medical imaging, coded excitation, high frequency ultrasound, digital signal processing

Affiliations:
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
41.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: 0041-624X, Vol.44, pp.121-129, 2006
Abstract:

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 non-compressed 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.

Keywords:

coded excitation, sound fields

Affiliations:
Nowicki A.-IPPT PAN
Klimonda Z.-IPPT PAN
Lewandowski M.-IPPT PAN
Litniewski J.-IPPT PAN
Lewin P.A.-Drexel University (US)
Trots I.-IPPT PAN
42.Trots I., Nowicki A., Lewandowski M., Litniewski J., Secomski W., Golay complementary codes, double pulse repetition frequency transmission, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.31, pp.35-40, 2006
Abstract:

This study concerns the development and investigation of a new composing method of short coded sequences and their transmission based on well-known Golay complementary codes and applied compression technique allowing to increase the signal-to-noise 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 32-bits pair Golay sequences and combined sequences consisting of two 16-bits 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.

Keywords:

Golay complementary sequences, double transmission, dead zone

Affiliations:
Trots I.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
Litniewski J.-IPPT PAN
Secomski W.-IPPT PAN
43.Klimonda Z., Lewandowski M., Nowicki A., Trots I., Lewin P.A., Direct and post-compressed sound fields for different coded excitations - experimental results, ARCHIVES OF ACOUSTICS, ISSN: 0137-5075, Vol.30, No.4, pp.507-514, 2005
Abstract:

Coded ultrasonography is intensively studied in many laboratories due to its remarkable properties: increased depth penetration, signal-to-noise ratio (SNR) gain and improved axial resolution. However, no data concerning the spatial behavior of the pressure field generated by coded bursts transmissions were reported so far. Five different excitation schemes were investigated. Flat, circular transducer with 15 mm diameter, 2 MHz center frequency and 50% bandwidth was used. The experimental data was recorded using the PVDF membrane hydrophone and collected with computerized scanning system developed in our laboratory. The results of measured pressure fields before and after compression were then compared to those recorded using standard ultrasonographic short-pulse excitation. The increase in the SNR of the decoded pressure fields is observed. The modification of the spatial pressure field distribution, especially in the intensity and shape of the sidelobes is apparent. Coded sequences are relatively long and, intuitively, the beam shape could be expected to be very similar to the sound field of long-period sine burst. This is true for non-compressed distributions of examined signals. However, as will be shown, the compressed sound fields, especially for the measured binary sequences, are similar rather to field distributions of short, wideband bursts.

Keywords:

coded excitation, ultrasonic field distribution, pulse compression, matched filtration, medical imaging

Affiliations:
Klimonda Z.-IPPT PAN
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
Trots I.-IPPT PAN
Lewin P.A.-Drexel University (US)
44.Nowicki A., Litniewski J., Secomski W., Trots I., Lewandowski M., Tymkiewicz R., Coded ultrasonography, Annual Report - Polish Academy of Sciences, ISSN: 1640-3754, pp.56-57, 2005
45.Wójcik J., Trots I., Lewandowski M., Nowicki A., Formulation of anisotropic failure criteria incorporating a microstructure tensor, COMPUTERS AND GEOTECHNICS, ISSN: 0266-352X, DOI: 10.1016/S0266-352X(99)00034-8, Vol.26, No.2, pp.105-112, 2000
Abstract:

Anisotropy is inherently related to microstructural arrangement within a representative volume of material. The microstructure can be represented by a second order tensor whose eigenvectors specify the orientation of the axes of material symmetry. In this paper, failure criteria for geomaterials are formulated in terms of the stress state and a microstructure tensor. The classical criteria for isotropic materials are generalized for the case of orthotropy as well as transverse isotropy. The proposed approach is illustrated by a simple example demonstrating the sensitivity of the uniaxial strength of the material to the orientation of the sample relative to the loading direction.

Affiliations:
Wójcik J.-IPPT PAN
Trots I.-IPPT PAN
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN

List of recent monographs
1.
503
Lewandowski M., Ultrasonografia kodowana: transmisja i kompresja w czasie rzeczywistym, Prace IPPT-IFTR REPORTS - Instytut Podstawowych Problemów Techniki PAN, 3, pp.1-183, 2009
List of chapters in recent monographs
1.
501
Wójcik J., Żołek N., Lewandowski M., Advances in Acoustics 2016, rozdział: Influence of transmission-reception characteristics of ultrasound transducers on statistics of echoesfrom nonhomogeneous media, Polish Acoustical Society, Warsaw Division, Institute of Fundamental Technological Research PAS, pp.627-633, 2016
2.
502
Lewandowski M., Computer Vision in Medical Imaging, World Scientific, rozdział: Medical Ultrasound Digital Signal Processing in the GPU Computing Era, C.H. Chen, 2, pp.229-244, 2014
3.
328
Lewandowski M., Walczak M., Karwat P., Nowicki A., Karłowicz P., Polskie protezy serca, opracowanie konstrukcji, badania kwalifikacyjne, przedkliniczne i kliniczne., rozdział: Wykonanie modelu i implementacja oprogramowania do ultradźwiękowego pomiaru przepływu krwi, FRK, Zabrze. Praca zbiorowa pod redakcją: Kustosz R., Gonsior M., Jarosz A., pp.3-21, 2013
4.
326
Nowicki A., Litniewski J., Trots I., Lewandowski M., Hydroacoustics of shallow water, rozdział: Encoded Ultrasound, Wydawnictwo Instytutu Podstawowych Problemów Techniki PAN, Warszawa, pp.181-208, 2013
5.
306
Tasinkevych Y., Klimonda Z., Lewandowski M., Nowicki A., Acoustical Imaging, rozdział: Sound Field Directivity Correction in Synthetic Aperture Algorithm for Medical Ultrasound, Springer, Nowicki A., Litniewski J., Kujawska T. (Eds.), 31, pp.169-179, 2012
6.
253
Lewandowski M., Ultrasound Imaging, rozdział: Hardware-Software Partitioning of Digital Signal Processing in Ultrasound Medical Devices a Case Study, Masayuki Tanabe, pp.1-16, 2011
7.
254
Trots I., Nowicki A., Lewandowski M., Tasinkevych Y., Ultrasound Imaging, rozdział: Synthetic Aperture Method in Ultrasound Imaging, Masayuki Tanabe, pp.37-56, 2011
8.
126
Nowicki A., Klimonda Z., Lewandowski M., Litniewski J., Lewin P.A., Trots I., Acoustical imaging, rozdział: Direct and post-compressed sound fields for different coded excitations, Springer, André M.P. et al (Eds.), 28, pp.399-407, 2007

Conference papers
1.Lewandowski M., Walczak M., Witek B., Steifer T., A GPU-based Ultrasound Phased-Array Research System for Non-destructive Testing, IUS 2016, IEEE International Ultrasonics Symposium, 2016-09-18/09-21, Tours (FR), DOI: 10.1109/ULTSYM.2016.7728843, pp.1-4, 2016
Abstract:

Ultrasound Phased-Array (PA) systems for nondestructive testing (NDT) use standard beamforming for line-byline image creation. New methods utilizing full-matrix capture (FMC) enable the application of advance processing algorithms, such as the total focusing method and multi-pass adaptive techniques for enhanced flaw visualization. The effective FMC data acquisition and its real-time processing require a very high data throughput and powerful computational resources. Most commercial PA systems support some form of FMC acquisition, but the limited external data bandwidth prevents this mode of operation from being useful. We have developed a fully programmable ultrasound research system capable of performing FMC data acquisition and image reconstruction with a high framerate. The ultrasound platform is supporting up to 192 parallel TX/RX electronics channels integrated with an embedded control PC and a GPU cluster for parallel processing. The implemented software libraries give the end-user control over TX/RX schemes, the acquisition process and signal processing algorithms. This all-in-one system is a fully flexible tool for the research and evaluation of novel Phased-Array FMC imaging methods and complex signal processing algorithms.

Keywords:

GPU, ultrasound, Phased-Array

Affiliations:
Lewandowski M.-IPPT PAN
Walczak M.-IPPT PAN
Witek B.-IPPT PAN
Steifer T.-IPPT PAN
2.Kustroń P., Korzeniowski M., Lewandowski M., Witek B., Rozbicki J., A High Frequency Ultrasonic Imaging of Welded Joints, IUS 2016, IEEE International Ultrasonics Symposium, 2016-09-18/09-21, Tours (FR), DOI: 10.1109/ULTSYM.2016.7728848, pp.1-4, 2016
Abstract:

The paper presents chosen results obtained during the investigation of welded joints (laser, spot and friction) tested using acoustic microscopy method. Detection of welds properties and the defects strongly depends on ultrasonic transducer’s parameters. For the purpose of this research a prototype hardware setup was built – enabling evaluation of various types of ultrasonic probes. The system can be easily adjusted to the geometry of an object and is well equipped with appropriate software for the analysis and processing of images such as B-scan or C-scan. The setup enables determination of welds geometry, in particular the depth of the weld penetration in some cases.

Keywords:

spot welds, high frequency ultrasonic imaging

Affiliations:
Kustroń P.-other affiliation
Korzeniowski M.-other affiliation
Lewandowski M.-IPPT PAN
Witek B.-IPPT PAN
Rozbicki J.-IPPT PAN
3.Steifer T., Klimonda Z., Lewandowski M., Multiply and Sum Spatial Compounding in Plane Wave Imaging, IUS 2016, IEEE International Ultrasonics Symposium, 2016-09-18/09-21, Tours (FR), DOI: 10.1109/ULTSYM.2016.7728887, pp.1-3, 2016
Abstract:

This paper is a part of the IUS 2016 Planewave Imaging Challenge submission. Spatial compounding of several low-resolution images taken from different angles is a well-established practice in ultrasound imaging. The usual procedure relies on averaging several images using arithmetic mean. An alternative approach is presented, which relies on multiplication of the low-resolution images.

Keywords:

ultrasound, plane wave imaging

Affiliations:
Steifer T.-IPPT PAN
Klimonda Z.-IPPT PAN
Lewandowski M.-IPPT PAN
4.Lewandowski M., Nowe metody syntetycznej apertury dla systemów Phased-Array, XXII Seminarium NIENISZCZĄCE BADANIA MATERIAŁÓW, 2016-03-16/03-18, Zakopane (PL), pp.83-92, 2016
Abstract:

Systemy UT z głowicami wieloelementowymi Phased-Array (PA) zapewniają wyższą jakość inspekcji i prędkość badania oraz różne mody skanowania i wizualizacji wad. Dostępne na rynku przenośne systemy PA zapewniają skanowanie i rekonstrukcję obrazów 2D w czasie rzeczywistym w oparciu o wyliczone i zaprogramowane prawa ogniskowania (ang. focal laws). Ta klasyczna metoda rekonstrukcji linii A-scan, z których następnie tworzony jest obraz 2D, nosi nazwę beamformingu. Metoda beamformingu podlega tym samym zasadom i ograniczeniom co badanie za pomocą równoważnej głowicy jednoelementowej (tj. o tej same aperturze, kącie i ogniskowaniu).
W referacie postaram się przedstawić zasadę działania metod syntetycznej apertury w sposób intuicyjny oraz zaprezentuję przykłady nowych aplikacji tej metody. Zainteresowanych odsyłam także do moich prezentacji zakopiańskich z lat ubiegłych, które dotyczyły podstaw fizycznych i metod rekonstrukcji w technice Phased-Array.

Keywords:

badania nieniszczące, technika ultradźwiękowa, systemy Phased-Array

Affiliations:
Lewandowski M.-IPPT PAN
5.Witek B., Walczak M., Lewandowski M., Characterization of the STHV748 Integrated Pulser for Generating Push Sequences, IUS 2015, IEEE International Ultrasonics Symposium, 2015-10-21/10-24, Taipei (TW), DOI: 10.1109/ULTSYM.2015.0522, pp.1-4, 2015
Abstract:

Ultrasound transmit push sequences put a high stress on a pulser IC due to power dissipation that could result in overheating. The aim of this work was to determine the safe range of parameters of push sequences for a high-voltage, high-speed, 4-channel pulser STHV748 (STMicroelectronics). The impact of using ceramic capacitors and electrolytic capacitors on the HV supply was also examined. The reaction of the pulser was measured with three output loading conditions. A safe range of values of pulser voltage for a given transmit frequency and sequence length were determined by monitoring chip temperature. Additionally, maximum pulse repetition frequency was evaluated in function of the maximum supply voltage. The STHV748 pulser is capable of generating push sequences. The duty-cycle is a key parameter that determines the safe operating conditions of the pulser. Limiting the amplitude of the HV supply enables us to increase push burst duration or decrease the frequency of the transmit signal.

Keywords:

acoustic radiation force, shear wave imaging, push sequences, HV pulser

Affiliations:
Witek B.-IPPT PAN
Walczak M.-IPPT PAN
Lewandowski M.-IPPT PAN
6.Nowicki A., Secomski W., Trawiński Z., Lewandowski M., Olszewski R., Estimation of Flow Mediated Vasodilation of the Radial Artery, IUS 2015, IEEE International Ultrasonics Symposium, 2015-10-21/10-24, Taipei (TW), DOI: 10.1109/ULTSYM.2015.0392, pp.1-4, 2015
Abstract:

Preceding atherosclerosis is endothelial dysfunction. There is therefore interest in the application of non-invasive clinical tools to assess endothelial function. There are commercially available ultrasound scanners to measure flow-mediated vasodilatation (FMD) of the brachial artery using 10-12 MHz linear array probes, however the attainable precision in estimating the changes in artery dilation does not exceeds 0.2 mm, far beyond the required one. We have introduced a high frequency scanning schemes 25-35MHz encoded (Golay) wobbling type imaging without Doppler (uScan developed in our lab, thick film wide bandwidth transducer, 50 microns axial resolution) and 20 MHz ultrasound (Ultrasonix) with 20 MHz pulsed Doppler attached to the linear array. The FMD results were normalized using AUC of shear rate at the radial artery wall.

Keywords:

thick-film transducers, flow-mediated vasolidation, radial artery, shear rate

Affiliations:
Nowicki A.-IPPT PAN
Secomski W.-IPPT PAN
Trawiński Z.-IPPT PAN
Lewandowski M.-IPPT PAN
Olszewski R.-other affiliation
7.Steifer T., Lewandowski M., Karwat P., Gawlikowski M., Automatic emboli detection system for the artificial heart, Physics Procedia, ISSN: 1875-3892, DOI: 10.1016/j.phpro.2015.08.254, Vol.70, pp.1181-1184, 2015
Abstract:

In spite of the progress in material engineering and ventricular assist devices construction, thromboembolism remains the most crucial problem in mechanical heart supporting systems. Therefore, the ability to monitor the patient’s blood for clot formation should be considered an important factor in development of heart supporting systems. The well-known methods for automatic embolus detection are based on the monitoring of the ultrasound Doppler signal. A working system utilizing ultrasound Doppler is being developed for the purpose of flow estimation and emboli detection in the clinical artificial heart ReligaHeart EXT. The system will be based on the existing dual channel multi-gate Doppler device with RF digital processing. A specially developed clamp-on cannula probe, equipped with 2 − 4MHz piezoceramic transducers, enables easy system setup. We present the issues related to the development of automatic emboli detection via Doppler measurements. We consider several algorithms for the flow estimation and emboli detection. We discuss their efficiency and confront them with the requirements of our experimental setup. Theoretical considerations are then met with preliminary experimental findings from a) flow studies with blood mimicking fluid and b) in-vitro flow studies with animal blood. Finally, we discuss some more methodological issues - we consider several possible approaches to the problem of verification of the accuracy of the detection system.

Keywords:

microemboli, embolism, Doppler ultrasound, ventricular assist device

Affiliations:
Steifer T.-IPPT PAN
Lewandowski M.-IPPT PAN
Karwat P.-IPPT PAN
Gawlikowski M.-other affiliation
8.Lewandowski M., Nowe metody i zastosowania ultradźwiękowych systemów Phased-Array, XXI Seminarium NIENISZCZĄCE BADANIA MATERIAŁÓW, 2015-03-18/03-20, Zakopane (PL), pp.135-143, 2015
Keywords:

ultradźwiękowe badania nieniszczące, głowice Phased-Array

Affiliations:
Lewandowski M.-IPPT PAN
9.Wójcik J., Trots I., Nowicki A., Lewandowski M., Cumulative method of image reconstruction in synthetic aperture - theory and experimental results, IUS 2013, IEEE International Ultrasonics Symposium, 2013-07-21/07-25, Praga (CZ), DOI: 10.1109/ULTSYM.2013.0528, Vol.1, pp.2068-2071, 2013
Abstract:

The Synthetic Aperture (SA) method provides a new solution in ultrasound diagnostics. It has particular importance in applications where frame rate and image resolution are crucial. Our new approach named Cumulative Synthetic Transmit Aperture (CSTA) allows optimizing SA in terms of memory size and computational power. The proposed CSTA algorithm requires 25 times less memory than a reference STA method for 64 elements transducer. This makes feasible implementation of CSTA on a low-power embedded GPU.

Keywords:

ultrasonic imaging, synthetic aperture, GPU

Affiliations:
Wójcik J.-IPPT PAN
Trots I.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
10.Walczak M., Lewandowski M., Żołek N., Optimization of real-time ultrasound PCIe data streaming and OpenCL processing for SAFT imaging, IUS 2013, IEEE International Ultrasonics Symposium, 2013-07-21/07-25, Praga (CZ), DOI: 10.1109/ULTSYM.2013.0527, Vol.1, pp.2064-2067, 2013
Abstract:

Our goal is to develop a complete ultrasound platform based on real-time SAFT (Synthetic Aperture Focusing Technique) GPU processing. We are planning to integrate all the ultrasound modules and processing resources (GPU) in a single rack enclosure with the PCIe switch fabric backplane. The first developed module (RX64) provides acquisition and streaming of 64 ultrasound channels. We implemented and benchmarked data streaming from the RX64 to the GPU memory and the SAFT image reconstruction on the GPU. A high system performance was achieved using hardware assisted direct memory transfers and pipelined processing workflow. The complete system throughput, including 128 channel data transfer at 16kS per line and low-resolution 256×256 pixel image SAFT reconstruction on a single Nvidia K5000 GPU, reached 450 fps. The obtained results proved the feasibility of the ultrasound real-time imaging system with GPU SAFT processing.

Keywords:

ultrasonic imaging, synthetic aperture, GPGPU, FPGA

Affiliations:
Walczak M.-IPPT PAN
Lewandowski M.-IPPT PAN
Żołek N.-IPPT PAN
11.Tasinkevych Y., Klimonda Z., Lewandowski M., Trots I., Nowicki A., Sound field directivity in multi-element synthetic transmit aperture method for ultrasound imaging, Conference on Medical Imaging - Physics of Medical Imaging, 2012-02-05/02-08, San Diego (US), DOI: 10.1117/12.910584, Vol.8313, pp.831369-1, 2012
Abstract:

A modified multi-element synthetic transmit aperture (MSTA) method for ultrasound imaging with RF echoes correction taking into account the influence of the element directivity is presented. The property is significant as the element width becomes commensurable with the wavelength of the emitted signal. The angular dependence of the radiation efficiency of the transmit/receive aperture is obtained from exact solution of the corresponding mixed boundary-value problem for periodic baffle system, modeling the transducer array. It is evaluated at the nominal frequency of the excitation signal and is implemented in the developed MSTA algorithm as apodization weights calculated for each imaging point and all combinations of the transmit/receive apertures. The performance of developed method is tested using FIELDII simulated synthetic aperture data of the point reflectors to estimate the visualization depth and lateral resolution. Besides, a FIELDII simulated and measurement data of cyst phantom are used for qualitative assessment of the imaging contrast. Comparison of the results obtained by the modified and conventional MSTA algorithms is given which reveals considerable improvement of the image quality in the area neighboring to the transducer’s aperture, and increase of the visualization depth at the cost of slight degradation of lateral resolution near the transducer face.

Keywords:

synthetic aperture, ultrasound imaging, beamforming

Affiliations:
Tasinkevych Y.-IPPT PAN
Klimonda Z.-IPPT PAN
Lewandowski M.-IPPT PAN
Trots I.-IPPT PAN
Nowicki A.-IPPT PAN
12.Karwat P., Klimonda Z., Lewandowski M., Nowicki A., Imaging Quality of the Classical Beamforming, SAFT and Plane Wave Imaging – Experimental Results, IUS 2012, IEEE International Ultrasonics Symposium, 2012-10-07/10-10, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0320, pp.1283-1286, 2012
Abstract:

The synthetic aperture focusing techniques (SAFT) are well known and widely deployed in radar techniques. Increasing processing power of modern computers allows effective implementation of various SAFT schemes in medical ultrasound systems with multi-element probes. The advance of the SAFT over the classical beamforming (BFR) is dynamic focusing in receive and transmit as well, which brings high resolution on every imaging point. We intend to develop the ultrasound imaging platform with some of the SAFT schemes implemented. The choice of the scheme must be preceded by examination of the imaging quality parameters. The results of the comparison of different SAFT schemes with conventional beamforming are presented in the paper. The results indicate that SAFT schemes can work better than BFR scheme. For example, for some point located near the center of the image the full width at half maximum (FWHM) was equal approximately 0.5, 0.4 and 0.3 mm, while the contrast-to-noise ratio (CNR) was equal 18, 19, and 19 dB for BFR, STA and PWI respectively.

Keywords:

Ultrasonic imaging, SAFT, Plane Wave Imaging

Affiliations:
Karwat P.-IPPT PAN
Klimonda Z.-IPPT PAN
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
13.Lewandowski M., Walczak M., Witek B., Kulesza P., Sielewicz K., Modular & Scalable Ultrasound Platform with GPU Processing, IUS 2012, IEEE International Ultrasonics Symposium, 2012-10-07/10-10, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0518, pp.2071-2074, 2012
Abstract:

The objective of our project is to develop a complete ultrasound platform with real-time GPU processing. The platform is designed to be modular and scalable both in number of ultrasound channels (64-256), as well as in communication bandwidth and processing power. By standardizing on the PCIe switch fabric, we are planning to integrate all the ultrasound modules and processing resources (GPU) in a single rack enclosure. Using PCIe direct peer-to-peer communication for transferring the data from the ultrasound acquisition modules to the GPUs, we maximize the system bandwidth and minimize CPU usage. The first developed module of our platform is RX64 - a 64-channel ultrasound acquisition PCIe card. The RX64 contains a high-end FPGA Altera Stratix IV 70 GX interfaced to: two 32-channels mixed-signal front-end ultrasound modules and two 64-bit 8GB DDR3 SO-DIMM memories for data buffering. We also develop GPU kernels for SAFT based ultrasound imaging, as well as GPU Framework for building complete signal processing pipeline.

Keywords:

ultrasonic imaging, synthetic aperture, GPU, FPGA

Affiliations:
Lewandowski M.-IPPT PAN
Walczak M.-IPPT PAN
Witek B.-IPPT PAN
Kulesza P.-IPPT PAN
Sielewicz K.-IPPT PAN
14.Lewandowski M., Sielewicz K., Walczak M., A Low-cost 32-channel Module with High-speed Digital Interfaces for Portable Ultrasound Systems, IUS 2012, IEEE International Ultrasonics Symposium, 2012-10-07/10-10, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0159, pp.639-642, 2012
Abstract:

There is a continuous trend towards small and portable ultrasound systems with multichannel processing. The objective of the work was to develop a modular acquisition and processing platform based on the following architecture principles: limited hardware processing, external high-speed data communication and software based on SAFT processing using embedded graphics processing unit (GPU). The acquisition module connected via PCIe or USB 3.0 interface can stream either raw RF data or demodulated ones. A low-power embedded PC with embedded GPU will implement ultrasound signal processing, as well as control and visualization functions. The performed feasibility study showed that AMD APU G-Series embedded x86 CPU+GPU is capable of real-time SAFT image reconstruction at limited resolution.

Keywords:

ultrasonic imaging, synthetic aperture, medical electronics, GPU, FPGA

Affiliations:
Lewandowski M.-IPPT PAN
Sielewicz K.-IPPT PAN
Walczak M.-IPPT PAN
15.Lewandowski M., Karwat P., Kudelka J., Kleczek T., GPU Implementation of the STA Algorithm on I/Q Data, IUS 2012, IEEE International Ultrasonics Symposium, 2012-10-07/10-10, Dresden (DE), DOI: 10.1109/ULTSYM.2012.0564, pp.2258-2261, 2012
Abstract:

GPU computing is a new paradigm in high performance signal and image processing. Massive parallel processing offered by the GPUs provides high acceleration of computations when they are properly implemented. Ultrasound image reconstruction is one of these highly parallel classes of algorithms. Massive amount of multichannel input data and deterministic order of execution makes US applications good candidates for high performance GPU implementation. Our goal is to design a versatile ultrasound platform with GPU real-time processing. The project is based on a new system architecture allowing for bandwidth and scalability of processing power. We implemented and optimized SAFT image reconstruction algorithms on CUDA. The study shows that a single GTX-580 GPU card is capable of reconstructing the 128-channel I/Q data into 256×256 High Resolution Images (HRI) at a frame-rate of 44.64 fps which is an equivalent of 5700 Low Resolution Images (LRI) per second.

Keywords:

ultrasonic imaging, synthetic aperture, GPU, CUDA

Affiliations:
Lewandowski M.-IPPT PAN
Karwat P.-IPPT PAN
Kudelka J.-other affiliation
Kleczek T.-other affiliation
16.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, 2011-10-18/10-21, Orlando (US), DOI: 10.1109/ULTSYM.2011.0117, pp.486-489, 2011
Abstract:

The paper presents a new yield criterion for the transversal isotropy of metal sheets under plane-stress 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 3-4, s. l85-2l5). 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 Newton-Raphson 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 Huber-Mises-Hencky yield condition and the proposed yield condition is presented.

Keywords:

bone scanner, trabecular bone, osteoporosis

Affiliations:
Litniewski J.-IPPT PAN
Cieślik L.-IPPT PAN
Lewandowski M.-IPPT PAN
Tymkiewicz R.-IPPT PAN
Zienkiewicz B.-IPPT PAN
Nowicki A.-IPPT PAN
17.Trots I., Tasinkevych Y., Nowicki A., Lewandowski M., Golay coded sequences in synthetic aperture imaging systems, 58 Otwarte Seminarium z Akustyki, 2011-08-13/08-16, Jurata (PL), pp.347-357, 2011
Abstract:

The paper presents the theoretical and experimental study of synthetic transmit aperture (STA) method combined with Golay coded transmission for medical ultrasound imaging applications. The transmission of long waveforms characterized by a particular autocorrelation function allows to increase the total energy of the transmitted signal without increasing the peak pressure. It can also improve signal-to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution.
In the work the 128-element linear transducer array with 0.3 mm pitch excited by the 8 and 16-bits Golay coded sequences as well as a one cycle at nominal frequencies 4 MHz were used. The comparison of 2D ultrasound images of the tissue mimicking phantoms is presented to demonstrate the benefits of coded transmission. The image reconstruction was performed using synthetic STA algorithm with transmit and receive signals correction based on a single element directivity function.

Keywords:

Golay codes, coded sequences, synthetic aperture, ultrasound imaging

Affiliations:
Trots I.-IPPT PAN
Tasinkevych Y.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
18.Tasinkevych Y., Trots I., Nowicki A., Lewandowski M., Optimal aperture in MSTA method for medical ultrasound imaging applications, 58 Otwarte Seminarium z Akustyki, 2011-08-13/08-16, Jurata (PL), pp.323-334, 2011
19.Cieślik L., Litniewski J., Lewandowski M., Nowicki A., Bone ultrasonic scanner, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.49-52, 2010
Abstract:

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.

Keywords:

trabecular bone, bone scanner, osteoporosis

Affiliations:
Cieślik L.-IPPT PAN
Litniewski J.-IPPT PAN
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
20.Trots I., Nowicki A., Lewandowski M., Tasinkevych Y., Multielement synthetic transmit aperture in medical ultrasound imaging, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.205-208, 2010
Abstract:

Synthetic aperture (SA) technique is a novel approach to today's commercial systems and has previously not been used in medical ultrasound imaging. The basic idea of SA is to combine information acquired simultaneously from all directions over a number of emissions and to reconstruct the full image from these data.
The paper describes the multielement STA method in medical ultrasound imaging with a small number of elements transmitting and all elements receiving apertures. Compared to other methods the multielement STA allows to increase the system frame rate and provides the best compromise between penetration depth and lateral resolution. In the experiments a 32-element linear transducer array with 0.48 mm inter-element spacing and a burst pulse of 100 ns duration were used. Two elements wide transmission aperture was used to generate an ultrasound wave covering the full image region. The comparison of 2D ultrasound images of tissue mimicking phantom obtained using STA and multielement STA methods are presented to demonstrate the benefits of the second method.

Keywords:

synthetic aperture, ultrasound imaging

Affiliations:
Trots I.-IPPT PAN
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
Tasinkevych Y.-IPPT PAN
21.Karwat P., Klimonda Z., Sęklewski M., Lewandowski M., Nowicki A., Metoda przerzedzania danych dla algorytmu syntetycznej apertury nadawczej, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.91-94, 2010
Abstract:

Metody ultradźwiękowego obrazowania struktur wewnętrznych człowieka są nieustannie ulepszane. Opracowywane są nowe algorytmy umożliwiające poprawę niektórych parametrów wynikowych. Przykładem jest metoda syntetycznej apertury (SA), która pozwala wyświetlać obrazy o wysokiej rozdzielczości z większą częstotliwością niż standardowa metoda formowania wiązki.
Ograniczeniem metody SA jest większa złożoność obliczeniowa, która przy znacznej ilości danych może uniemożliwić osiągnięcie pożądanej szybkości rekonstrukcji. Problem ten można ominąć rezygnując z części zarejestrowanych sygnałów. Wiąże się to oczywiście z pogorszeniem jakości obrazowania, jednak przy odpowiedniej technice przerzedzania danych degradacja obrazu jest niewielka. Proponowany sposób przerzedzania ma zastosowanie w metodzie syntetycznej apertury nadawczej (STA) i opiera się na założeniu, że sygnał uzyskany za pomocą dowolnej pary przetworników jest taki sam niezależnie od tego, który z przetworników nadawał, a który odbierał. W tej sytuacji można pominąć blisko połowę zapisanych danych i wciąż
możliwe będzie zrekonstruowanie obrazu w poprzedniej jakości. Na podstawie prezentowanych wyników symulacji oraz pomiarów na fantomach nitkowym i tkankowym wykazano, że stosując opisaną technikę przerzedzania można zmniejszyć o połowę ilość danych przy zachowaniu rozdzielczości i nieznacznym spadku parametru SNR oraz kontrastu rekonstruowanych obrazów.

Keywords:

metody syntetycznej apertury, przerzedzanie danych

Affiliations:
Karwat P.-IPPT PAN
Klimonda Z.-IPPT PAN
Sęklewski M.-IPPT PAN
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
22.Sęklewski M., Karwat P., Klimonda Z., Lewandowski M., Nowicki A., Preliminary results: analysis of Synthetic Transmit Aperture technique in ultrasonic imaging, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.173-176, 2010
Abstract:

The Synthetic Aperture (SA) methods are widespread and successfully used in radar technology, as well as in the sonar systems. The advantages of relatively good resolution in the whole area of scanning without decrease of framerate, make this technique an object of interest in medical imaging methods such as ultrasonography (US).This paper describes the possible usage of the SA method in ultrasound imaging. The measurements of different SA schemes were conducted using the set-up consisting of the research ultrasonograph module, the PC and the special wire phantom. The results for different schemes of image reconstruction are presented. Particularly the Synthetic Transmit Aperture (STA) technique was concerned. Results of the STA method are discussed in this paper.

Keywords:

ultrasonic imaging, synthetic aperture focusing technique

Affiliations:
Sęklewski M.-IPPT PAN
Karwat P.-IPPT PAN
Klimonda Z.-IPPT PAN
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
23.Walczak M., Kulesza P., Lewandowski M., Karwat P., Witek B., Implementacja w układzie FPGA wybranego filtru ech stałych dla wielobramkowego systemu Dopplera przezczaszkowego, 57 Otwarte Seminarium z Akustyki, 2010-09-20/09-24, Gliwice (PL), pp.209-212, 2010
Abstract:

W artykule opisano wybór i implementację filtrów ech stałych w programowalnych układach logicznych (FPGA) dla ultradźwiękowego wielobramkowego systemu przezczaszkowego przepływomierza krwi opracowywanego w Zakładzie Ultradźwięków IPPT PAN. Implementacja filtrów w FPGA miała na celu redukcję obciążenia softwarowego przetwarzania sygnałów dopplerowskich. W pracy przedstawiono badania modelowe i porównanie filtrów ech stałych o skończonej odpowiedzi impulsowej (SOI) oraz nieskończonej odpowiedzi impulsowej (NOI). Przeanalizowany został zakres stabilnej pracy filtru NOI. Wyselekcjonowany filtr górnoprzepustowy typu SOI został następnie zaimplementowany i zoptymalizowany do architektury układów FPGA oraz zastosowania w przepływomierzu. Zastosowano ekonomiczny układ FPGA Altera Cyclone III EP3C25F324C8. Opracowany filtr ech stałych realizuje 100 identycznych górnoprzepustowych filtrów typu SOI, co zapewnia filtrowanie sygnału dopplerowskiego w 100 bramkach jednocześnie. Filtry operują na 16 bitowych próbkach sygnału, a ich charakterystyka jest programowalna przez 65 16-bitowych współczynników. Zweryfikowano poprawność przetwarzania na komputerze PC w środowisku Altera Quartus II 9.1 oraz ModelSim 6.5b poprzez symulacje i porównanie odpowiedzi impulsowej oraz skokowej filtrów. W wyniku opisanych prac powstała struktura logiczna filtru ech stałych przeznaczona do implementacji w układzie FPGA Cyclone III, zajmująca 5% zasobów logicznych układu oraz 34% zasobów pamięciowych.

Keywords:

ultradźwiękowy Doppler przezczaszkowy, filtry ech stałych, cyfrowe przetwarzanie, FPGA

Affiliations:
Walczak M.-IPPT PAN
Kulesza P.-IPPT PAN
Lewandowski M.-IPPT PAN
Karwat P.-IPPT PAN
Witek B.-IPPT PAN
24.Lewandowski M., Klimonda Z., Karwat P., Sęklewski M., Nowicki A., Bassi L., Tortoli P., Comparison of different schemes of synthetic transmit aperture using an ultrasound advanced open platform (ULA-OP), IUS 2010, IEEE International Ultrasonics Symposium, 2010-10-11/10-14, San Diego (US), DOI: 10.1109/ULTSYM.2010.5935656, pp.1988-1991, 2010
Abstract:

Increasing efforts are currently dedicated to incorporate the Synthetic Transmit Aperture (STA) method in ultrasound imaging systems. The STA technique can provide a pixel-like focusing (dynamic focusing at both transmit and receive) without impairment of the frame rate. This goal can only be achieved by a careful design of the transmission and reception schemes. In this paper, the preliminary results of resolution, Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR) measurements for a specific SA scheme with different transmit apertures are presented. The measurements were made using a novel ultrasound advanced open platform (ULA-OP) developed at the University of Florence. The ULA-OP is fully programmable and enables access to the RF echo-data from each transducer element.

Keywords:

synthetic aperture, ultrasound open platform

Affiliations:
Lewandowski M.-IPPT PAN
Klimonda Z.-IPPT PAN
Karwat P.-IPPT PAN
Sęklewski M.-IPPT PAN
Nowicki A.-IPPT PAN
Bassi L.-other affiliation
Tortoli P.-other affiliation
25.Nowicki A., Wójcik J., Lewandowski M., Tymkiewicz R., Lou-Moller R., Wolny W., Zawada T., Thick film transducers for high frequency coded ultrasonography, 9th International Conference on Information Technology and Applications in Biomedicine, 2009-11-04/11-07, Larnaka (CY), DOI: 10.1109/ITAB.2009.5394411, pp.1-4, 2009
Abstract:

Recently a new technology of piezoelectric transducers based on PZT thick film has been developed as a response to a call for devices working at higher frequencies suitable for production in large numbers at low cost. Eight PZT thick film based focused transducers with resonant frequency close to 40 MHz were fabricated and experimentally investigated. The PZT thick films were deposited on acoustically engineered ceramic substrates by pad printing. Considering high frequency and nonlinear propagation it has been decided to evaluate the axial pressure field emitted (and reflected by thick metal plate) by each of concave transducer differing in radius of curvature - 11 mm, 12 mm, 15 mm, 16 mm.
All transducers were activated using AVTEC AVG-3A-PS transmitter and Ritec diplexer connected directly to Agilent 54641D oscilloscope. As anticipated, in all cases the focal distance was up to 10% closer to the transducer face than the one related to the curvature radius. Axial pressure distributions were also compared to the calculated ones (with the experimentally determined boundary conditions) using the angular spectrum method including nonlinear propagation in water. The computed results are in a very good agreement with the experimental ones. The transducers were excited with Golay coded sequences at 35-40 MHz. Introducing the coded excitation allowed replacing the short-burst transmission at 20 MHz with the same peak amplitude pressure, but with almost double center frequency, resulting in considerably better axial resolution. The thick films exhibited at least 30% bandwidth broadening comparing to the standard PZ 27 transducer, resulting in an increase in matching filtering output by a factor of 1.4-1.5 and finally resulting in a SNR gain of the same order. Examples of skin scans obtained with the new thick-film transducers are presented.

Keywords:

transducers, thick film, high frequency ultrasound, pulse compression, Golay code

Affiliations:
Nowicki A.-IPPT PAN
Wójcik J.-IPPT PAN
Lewandowski M.-IPPT PAN
Tymkiewicz R.-IPPT PAN
Lou-Moller R.-InSensor A/S (DK)
Wolny W.-InSensor A/S (DK)
Zawada T.-Ferroperm Piezoceramics A/S (DK)
26.Lewandowski M., Walczak M., Nowicki A., Compact modular Doppler system with digital RF processing, IUS 2009, IEEE International Ultrasonics Symposium, 2009-09-20/09-23, Rzym (IT), DOI: 10.1109/ULTSYM.2009.5441933, pp.1848-1851, 2009
Abstract:

Doppler instruments are widely used for evaluation of the hemodynamic of vascular circulation. The objective of the work was to develop a modular acquisition and processing system to enable the construction of various ultrasound instruments. The developed system consists of two electronic boards with dimensions of 130x82mm in sandwich configuration. Digital signal processing was based on an efficient DSP (Blackfin BF537, Analog Devices, USA) with 128MB RAM and an FPGA (Cyclone III EP3C25, Altera, USA). The system can work as a standalone device with the limited user interface or as a PC peripheral under the control of the application software. The dual channel transcranial PW Doppler flowmeter with multigate processing has been the first application of the developed platform. The acquisition module provides the A/D sampling at 64 MSPS rate with 14-bits resolution and supports ultrasonic transducers within the range of 1–16 MHz. The PC software performs signal processing and visualization of color Doppler, spectrum, flow profile and audio. The developed system is a modern technical solution which enables to build portable Doppler instruments of different classes. The developed prototype of transcranial Doppler will be introduced into production soon.

Keywords:

ultrasound Doppler systems, transcranial aplications, digital RF processing, DSP, FPGA

Affiliations:
Lewandowski M.-IPPT PAN
Walczak M.-IPPT PAN
Nowicki A.-IPPT PAN
27.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, 2009-09-20/09-23, Rzym (IT), DOI: 10.1109/ULTSYM.2009.5441930, pp.2383-2385, 2009
Abstract:

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 focusing-induced mean frequency
shift (MFS) of the propagating pulse. The method corrects mean frequency estimates derived from echo pulses propagating in attenuating tissue with locally varying attenuation coefficient. The FC algorithm applies the diffraction correcting coefficients obtained experimentally from the probing pulses focused in water for assessing the expected values of MFS of pulses focused in attenuating tissue. The calculations involves the pulse ‘history’ that due to overall attenuation along the traveled path downshifts the pulse spectrum resulting in variation of the focusinginduced MFS obtained in water.

Keywords:

attenuation estimation, difraction correction, parametric imaging

Affiliations:
Litniewski J.-IPPT PAN
Klimonda Z.-IPPT PAN
Lewandowski M.-IPPT PAN
Nowicki A.-IPPT PAN
Szymańska E.-other affiliation
28.Trots I., Nowicki A., Secomski W., Litniewski J., Lewandowski M., Transducer Bandwidth Influence on the Golay Encoded Ultrasound Echoes, IUS, IEEE Ultrasonics Symposium, 2007-10-28/10-31, New York (US), DOI: 10.1109/ULTSYM.2007.320, pp.1274-1277, 2007
Abstract:

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 pulse-echo 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 signal-to-noise-ratio (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 wide-band, composite ones.

Keywords:

ultrasound imaging, coded transmission, transducer badnwidth, Golay codes

Affiliations:
Trots I.-IPPT PAN
Nowicki A.-IPPT PAN
Secomski W.-IPPT PAN
Litniewski J.-IPPT PAN
Lewandowski M.-IPPT PAN

Conference abstracts
1.Nowicki A., Lewandowski M., Trots I., Olszewski R., High Frequency Thick Film Ultrasonic Transducers Used for Estimation of Flow-Mediated Vasodilation of the Radial Artery, SENSORDEVICES 2015, 6th International Conference on Sensor Device Technologies and Applications, 2015-08-23/08-28, Wenecja (IT), pp.99-100, 2015
Abstract:

Preceding atherosclerosis is an endothelial dysfunction. Therefore there is a growing interest in the application of non - invasive clinical tools to assess endothelial function. Commercially available ultrasound machines can measure flow - mediated vasodilatation of the brachial artery using maximum 10-12 MH z linear probes. The higher the probe frequency, the better the axial resolution. Recently, a new technology of piezoelectric transducers based on PZT thick film technology has been developed in Meggitt (Denmark) as a response to a call for devices working at higher frequencies. The thick films exhibited at least 30% bandwidth broadening comparing to the standard PZ 27 transducers, resulting in an increase in match filtering encoding output by a factor of 1.4 - 1.5 and finally resulting in a signal to noise gain of the same order. The introduction of a high frequency 25 - 30 MHz ultrasound scanner to measure radial artery diameter after reactive hyperemia open s a new window for more precise imaging of endothelial function.

Keywords:

thick film transducers, atherosclerosis, flow mediated vaso dilation

Affiliations:
Nowicki A.-IPPT PAN
Lewandowski M.-IPPT PAN
Trots I.-IPPT PAN
Olszewski R.-other affiliation
2.Walczak M., Lewandowski M., Żołek N., A real-time streaming DAQ for Ultrasonix Research scanner, IUS 14, IEEE International Ultrasonics Symposium, 2014-09-03/09-06, Chicago (US), DOI: 10.1109/ULTSYM.2014.0310, pp.1257-1260, 2014
Abstract:

A new 128 channel parallel acquisition module for the Ultrasonix SonixTouch ultrasound scanner was developed. Although the module provides similar functionality to the original SonixDAQ system, it presents new possibilities of real-time data streaming and processing on GPU, thanks to a fast PCIe communication interface. Direct access and processing of pre-beamformed channel data with fully programmable transmit schemes enables the research implementation of new advanced imaging modalities (eg. plane wave imaging, vector Doppler, shear wave elastography). The presented RX-DAQ system is enriched with a GPU software framework, for Python and Matlab, enabling the integration of user processing functions.

Keywords:

ultrasonic imaging, pre-beamformed data, real-time processing, GPU, FPGA

Affiliations:
Walczak M.-IPPT PAN
Lewandowski M.-IPPT PAN
Żołek N.-IPPT PAN
3.Lewandowski M., Walczak M., Karwat P., Witek B., Nowicki A., Karłowicz P., Research & Medical Doppler platform, 11th Congrès Français d'Acoustique, 2012 IOA annual meeting, 2012-04-23/04-27, Nantes (FR), pp.x1-x6, 2012
Abstract:

A new ultrasound digital transcranial Doppler system (digiTDS) is introduced. The digiTDS enables diagnosis of intracranial vessels which are difficult to penetrate for standard systems. The device can display a color map of flow velocities in time-depth domain and a spectrogram of a Doppler signal received from a particular depth. The system offers a multigate processing that allows to display simultaneously a number of spectrograms and to reconstruct a flow velocity profile. The digital signal processing in digiTDS is partitioned between hardware and software parts. The hardware part (based on FPGA) executes a signal demodulation and reduces data stream. The software part (PC) performs the Doppler processing and display tasks. The hardware-software partitioning allowed to build a flexible Doppler platform at a relatively low cost. The digiTDS design fulfills all necessary medical standards being a new useful tool in transcranial field as well as in heart velocimetry research.

Keywords:

ultrasound transcranial Doppler, RF signal processing, DSP, FPGA

Affiliations:
Lewandowski M.-IPPT PAN
Walczak M.-IPPT PAN
Karwat P.-IPPT PAN
Witek B.-IPPT PAN
Nowicki A.-IPPT PAN
Karłowicz P.-other affiliation

Patents
Numer/data zgłoszenia patentowego
Ogłoszenie o zgłoszeniu patentowym
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pdf
417777
2016-06-30
BUP 2/2017
2017-01-16
Dębowski T., Lewandowski M., Mackiewicz S., Ranachowski Z., Hoła J., Schabowicz K.
Sposób wykrywania delaminacji w płytach włókno-cementowych i urządzenie do wykrywania delaminacji w płytach włókno-cementowych
PL, Politechnika Wrocławska, Instytut Podstawowych Problemów Techniki PAN
227043
WUP 10/2017
2017-10-31