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1

The Acoustic Field Distribution Inside the Ultrasonic Ring Array

Staszewski W., Gudra T., Opieliński K. J.

Archives of Acoustics

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2018

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Vol. 43, No. 3

455--463

EN

This paper presents and analyses the results of a simulation of the acoustic field distribution in sectors of a 1024-element ring array, intended for the diagnosis of female breast tissue with the use of ultrasonic tomography. The array was tested for the possibility to equip an ultrasonic tomograph with an additional modality - conventional ultrasonic imaging with the use of individual fragments (sections) of the ring array. To determine the acoustic field for sectors of the ring array with a varying number of activated ultrasonic transducers, a combined sum of all acoustic fields created by each elementary transducer was calculated. By the use of MATLAB software, a unique algorithm was developed, for a numerical determination of the distribution of pressure of an ultrasonic wave on any surface or area of the medium generated by the concave curvilinear structure of rectangular ultrasound transducers with a geometric focus of the beam. The analysis of the obtained results of the acoustic field distribution inside the ultrasonic ring array used in tomography allows to conclude that the optimal number of transducers in a sector enabling to obtain ultrasound images using linear echographic scanning is 32 ≤ n ≤ 128, taking into account that due to an increased temporal resolution of ultrasonic imaging, this number should be as low as possible.

2

Model of multipath propagation of ultrasonic pulses generated in soft tissue by linear arrays

Celmer M., Opieliński K. J.

Hydroacoustics

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2016

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Vol. 19

37--48

EN

Arrays of ultrasonic transducers used in medical diagnosis for safe and non-invasive visualization of the inside of a human body usually consist of many elementary piezoceramic transducers. In such an electromechanical construction of the array, while activating individual transducers, creation of crosstalk can be observed in the form of propagation of electric voltage and mechanical vibration on neighboring elements, which leads to distortion of the generated acoustical field, and in consequence reduces the quality of reconstructed medical images. Complexity of the problem rises rapidly in the case of arrays forming ultrasonic beams. In this paper, authors developed a numerical amplitude-phase model of multipath propagation of ultrasonic pulses generated in a soft tissue-like medium by such arrays. The model allowed simulation of acoustic field distributions, and to examine the influence of beam focusing in transmission mode on these distributions, taking into account electrical and mechanical crosstalk.

3

Bioacoustic range equation

Opieliński K. J., Gudra T.

Hydroacoustics

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2016

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Vol. 19

307--318

EN

In order to describe and analyze the bioacoustic link, the authors of this study used a modified range explicit equation formulated for a hydroacoustic link. The equation makes it possible to design a bioacoustic link by assuming a given study range in a biological medium, and estimating the required power ratio or power level drop, and then selecting a value for the ratio by means of ultrasonic transducer parameters. A biological medium submerged in water between a transmitting and receiving ultrasonic transducer was studied in a streamlined manner as quasi-homogeneous, or more specifically, in the form of a multilayered tissue structure with parallel border surfaces. In the paper, sample calculations of the relation between power level drop and the length of the bioacoustic link in biological media, for ultrasonic wave frequency in the range of 1 – 5 MHz were performed; using a modified range explicit equation formulated for a hydroacoustic link. The calculations were verified in an experiment.

4

Ultrasonic Mammography with Circular Transducer Array

Opieliński K. J., Pruchnicki P., Gudra T.

Archives of Acoustics

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2014

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Vol. 39, No. 4

559--568

EN

Ultrasonic projection imaging is similar to X-ray radiography. Nowadays, ultrasonic projection methods have been developed in the set-up of multi-element flat arrays with miniature transducers, where one of the array acts as a transmitter and the other one is a receiver. In the paper, a new method of the projection imaging using a 1024-element circular ultrasonic trans- ducer array is presented. It allows the choice of a projection scanning plane for any angle around a studied object submerged in water. Fast acquisition of measurement data is achieved as a result of parallel switch- ing of opposite transmitting and receiving transducers in the circular array and vertical movement of the array. The algorithm equalizing the length of measurement rays and the distances between them was elaborated for the reconstruction of projection images. Projection research results of breast phantom obtained by means of the elaborated measurement set- up and compared with mammography simulations (acquired through overlapping of X-ray tomographic images) show that ultrasonic projection method presented in this paper (so-called ultrasonic mammogra- phy) can be applied to the woman’s breast and be used as a diagnosis for an early detection of cancerous lesions. It can, most of all, be used as an alternative or complementary method to standard mammog- raphy, which is harmful because of ionizing radiation and invasive due to the mechanical compression of tissue.

5

Ultrasound Transmission Tomography Imaging of Structure of Breast Elastography Phantom Compared to US, CT and MRI

Opieliński K. J., Pruchnicki P., Gudra T., Podgórski P., Kraśnicki T., Kurcz J., Sąsiadek M.

Archives of Acoustics

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2013

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Vol. 38, No. 3

321--334

EN

The paper presents an analysis of the results of ultrasound transmission tomography (UTT) imaging of the internal structure of a breast elastography phantom used for biopsy training, and compares them with the results of CT, MRI and, conventional US imaging; the results of the phantom examination were the basis for the analysis of UTT method resolution. The obtained UTT, CT and MRI images of the CIRS Model 059 breast phantom structure show comparable (in the context of size and location) heterogeneities inside it. The UTT image of distribution of the ultrasound velocity clearly demonstrates continuous changes of density. The UTT image of derivative of attenuation coefficient in relation to frequency is better for visualising sharp edges, and the UTT image of the distribution of attenuation coefficient visualises continuous and stepped changes in an indirect way. The inclusions visualized by CT have sharply delineated edges but are hardly distinguishable from the phantom gel background even with increased image contrast. MRI images of the studied phantom relatively clearly show inclusions in the structure. Ultrasonography images do not show any diversification of the structure of the phantom. The obtained examination results indicate that, if the scanning process is accelerated, ultrasound transmission tomography method can be successfully used to detect and diagnose early breast malignant lesions. Ultrasonic transmission tomography imaging can be applied in medicine for diagnostic examination of women’s breasts and similarly for X-ray computed tomography, while eliminating the need to expose patients to the harmful ionising radiation.

6

Narrow Beam Ultrasonic Transducer Matrix Model for Projection Imaging of Biological Media

Opieliński K. J., Gudra T., Pruchnicki P.

Archives of Acoustics

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2010

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Vol. 35, No. 1

91-109

EN

The following paper presents an idea of minimising the number of connections of individual piezoelectric transducers in a row-column multielement passive matrix system used for imaging of biological media structure by means of ultrasonic projection. It allows to achieve significant directivity with acceptable input impedance decrease. This concept was verified by designing a model of a passive ultrasonic matrix consisting of 16 elementary piezoceramic transducers, with electrode attachments optimised by means of electronic switches in rows and columns. Distributions of acoustic field generated by the constructed matrix model in water and results of the calculations conformed well.

7

A Digitally Controlled Model of an Active Ultrasonic Transducer Matrix for Projection Imaging of Biological Media

Opieliński K. J., Gudra T., Pruchnicki P.

Archives of Acoustics

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2010

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Vol. 35, No. 1

75-90

EN

The following work presents the idea of constructing a digitally controlled active piezoceramic transducer matrix for ultrasonic projection imaging of biological media in a similar way as in case of roentgenography (RTG). Multielement ultrasonic probes in the form of flat matrices of elementary piezoceramic transducers require attaching a large number of electrodes in order to activate the individual transducers. This paper presents the idea of minimising the number of transducer connections in an active row-column matrix system. This idea was verified by designing a model of a matrix consisting of 16 ultrasonic transducers with electrode attachments optimised by means of electronic switches in rows and columns and miniature transistor switches in the nodes of the matrix allowing to activate selected transducers. The results of measurements and simulations of parameters of the designed matrix show that it is suitable to be used in projection imaging of biological media as a sending probe. In to use the matrix as a universal sending or receiving probe, it was suggested to add further switches that would eliminate the undesired effect of crosstalks in case of switches used for toggling the transducers in the nodes of the matrix.

8

Non-contacting examination of materials using airborne ultrasonic transducer

Gudra T., Opieliński K. J., Kozłowski P. P.

Molecular and Quantum Acoustics

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2008

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Vol. 29

93-108

EN

In the paper a non-contacting ultrasonic examination of materials is presented. This method is based on the use of air or another gas as a transmission medium for ultrasonic waves between probes and the examined material. This paper concentrates on examination of three materials: polyurethane foam, balsa wood along and across fibres and porous ceramics. It was shown that quality assessment of different material is possible on the basis of spectral analysis of ultrasonic signal transmitted through a sample.

9

Ultrasonic parameters of hen's egg

Opieliński K. J.

Molecular and Quantum Acoustics

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2007

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Vol. 28

203-216

EN

Hen’s egg is an easily accessible biomolecular model for ultrasonic study. It is a perfect object, allowing testing of the visualization possibilities by means of ultrasound transmission tomography. The aim of paper is showing complex characteristics of the ultrasonic parameters of hen’s egg in the frequency range 1–10 MHz.

10

Symulacja akustyki środowisk i pomieszczeń za pomocą komputerowych systemów edycji dźwięku

Opieliński K. J., Rychlicki J. J.

Prace Naukowe Instytutu Telekomunikacji i Akustyki Politechniki Wrocławskiej. Konferencje

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2004

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Vol. 85, nr 29

135-142

PL

W pracy dokonano przeglądu metod modelowania akustyki s'rodowisk i pomieszczeń (metoda geometryczna, filtracja grzebieniowa, odpowiedź impulsowa) implementowanych w profesjonalnych, komputerowych systemach edycji dźwięku (DAW). Narzędzia efektowe wielu programów wykorzystywanych w studiach nagraniowych zbadano pod kątem możliwości symulowania akustyki określonych plenerów i wnętrz.

EN

In the paper, the methods of media and rooms acoustics modelling (geometrical method, comb filtering, pulse response) implemented in professional digital audio workstations (DAW), were discussed. The effect tools of software used in many recording studios were examined with regard to ambient simulation possibilities of specific open spaces and closed interiors.

11

Problem opóźnień w komputerowych systemach edycji dźwięku

Opieliński K.J.

Prace Naukowe Instytutu Telekomunikacji i Akustyki Politechniki Wrocławskiej. Konferencje

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2003

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Vol. 84, nr 28

9-16

EN

In the paper, the kinds of delays and the reasons why its appear in the modern sound recording techniques by means of digital audio workstations, were discussed; the way and the range of delay influence on sound was determined on the basis of experimental research as well as the appriopriate methods of its compensation and removing were presented.

12

Synchronizacja fal mózgowych za pomocą dźwięku

Opieliński K.J., Doros G.

Prace Naukowe Instytutu Telekomunikacji i Akustyki Politechniki Wrocławskiej. Konferencje

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2001

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Vol. 83, nr 27

347-354

EN

In the paper, the problem of creation and listening of sound making possible to synchronize various brainwave forms is presented. It is the way to induce different states of consciousness as well as physical and emotional states. In order to test the effectiveness of this method, binaural beat influence mental slates and its affect memorizing efficiency was examined for small group of listeners using suitably prepared sound stimulation.

13

Adaptation of image reconstruction algorithm for purposes of ultrasound transmission tomography (UTT)

Dobrucki A. B., Opieliński K. J.

Archives of Acoustics

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2000

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Vol. 25, no. 4

395-422

EN

In this research, the convolution and backprojection method has been adapted for the purposes of image reconstruction in ultrasound transmission tomography (UTT). In particular, a complete computer algorithm enabling the use of different convolving and interpolation functions has been developed. A technique of reducing and scaling the tomographic measuring data to minimize the reconstruction errors is proposed. The convolution and backprojection method was optimized through a choice of a versatile convolving function and a simple interpolation function, and it was tested using simulated and actual tomographic measuring data. After reconstruction, good-quality images were obtained. It has been found that the number of measuring rays determines the resolution of an image, the accuracy with which the size of structures is imaged and the accuracy with which the image point values are reconstructed, whereas the number of measuring projections determines the dynamics and distortion of an image. Because of computation time and image blur, an optimum reconstruction grid size, according to the visualization quality criterion, should be chosen. The convolution and backprojection algorithm optimized in this research can be applied directly to the UTT visualization of the internal structure of objects as a distribution of local sound velocities in this structure, reconstructed on the basis of measurements of mean times of the passage of an ultrasonic wave through a cross-section of an object immersed in water, in a parallel ray projection geometry.