Wojciech Secomski

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This paper describes a novel approach to estimate broadband ultrasound attenuation (BUA) in a bone structure in human in vivo using coded excitation. BUA is an accepted indicator for assessment of osteoporosis. In the tested approach a coded acoustic signal is emitted and then the received echoes are compressed into brief, high amplitude pulses making use(More)
The pressure gradient along the ultrasonic beam results in medium streaming. Following Nyborg's analysis of the Navier-Stokes equation, Wu and Du developed an approximate solution for the streaming velocity generated by flat and weakly focused transducers. We have modified their solution of the Poisson equation by directly deriving the Dirichlet boundary(More)
This study presents the detailed construction and the principle of performance of high frequency (HF) ultrasound scanner for skin examination. The aim of this study was to show a difference between diseased and healthy skin and to evaluate the usefulness of the scanner in monitoring of therapeutic efficacy of morphea and lichen sclerosus et atrophicus(More)
A clinically applicable method for noninvasive measurement of hematocrit based on 20 MHz multigate Doppler ultrasound was developed. The ultrasound attenuation coefficient in blood is obtained by measuring the power of the signal coming from gates at different depths. A robust averaging method is introduced, which provides stable and repeatable results by(More)
In contrast to previously published papers [A. Nowicki, Z. Klimonda, M. Lewandowski, J. Litniewski, P.A. Lewin, I. Trots, Comparison of sound fields generated by different coded excitations - Experimental results, Ultrasonics 44 (1) (2006) 121-129; J. Litniewski, A. Nowicki, Z. Klimonda, M. Lewandowski, Sound fields for coded excitations in water and(More)
An approximate solution for the streaming velocity generated by flat and weakly focused transducers was derived by directly solving the Dirichlet boundary conditions for the Poisson equation, the solution of the Navier-Stokes equation for the axial components of the streaming velocity. The theoretical model was verified experimentally using a 32 MHz pulsed(More)
OBJECTIVE To develop a clinically applicable method for noninvasive acoustic determination of hematocrit values in vivo. METHODS The value of hematocrit was determined initially in vitro from the pulseecho measurements of acoustic attenuation. The testing was carried out in a laboratory setup with an ultrasonic transducer operating at 20 MHz and with the(More)
A tissue thermal conductivity (Ks) is an important parameter which knowledge is essential whenever thermal fields induced in selected organs are predicted. The main objective of this study was to develop an alternative ultrasonic method for determining Ks of tissues in vitro suitable for living tissues. First, the method involves measuring of(More)
We present a new method that uses nonlinear properties of tissue to improve contrast-to-noise ratio. In our novel method, the acoustic source is activated with two tone-bursts (2.2 and 4.4 MHz), with specially designed polarization of the individual tone-burst. This new approach is called multitone nonlinear coding (MNC) because the choice of polarization(More)
The issue of maximizing penetration depth with concurrent retaining or enhancement of image resolution constitutes one of the time invariant challenges in ultrasound imaging. Concerns about potential and undesirable side effects set limits on the possibility of overcoming the frequency dependent attenuation effects by increasing peak acoustic amplitudes of(More)