Wave Generation by a Finite Baffle Array in Application to Beam-Forming Analysis

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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 signalto-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.

Section: Resultsmentioning

confidence: 99%

Golay Coded Sequences in Synthetic Aperture Imaging Systems

Trots¹,

Tasinkevych²,

Nowicki³

et al. 2011

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“…In order to account for the multi-element transmit aperture the proper modification of the MSTA method is required. To this end the results of the full-wave analysis of the radiation and scattering problem for a periodic (Tasinkevych, Danicki, 2010; Tasinkevych, Danicki, 2011) or a finite (Tasinkevych, 2010) baffle system can be applied for the purpose of modelling the directivity properties of the transmit aperture comprising several elements. The method is based on the BIS-expansion (Bloteker et al, 1973), which was successfully applied to solving electrostatic problems in the theory of surface acoustic wave transducers (Danicki, Tasinkevych, 2006), in the theory of elastic wave scattering by periodic cracks (Danicki, 2002) and in the theory of EM scattering by periodic structures (Tasinkevych, 2008;2009;2011).…”

Section: Discussionmentioning

confidence: 99%

Optimization of the Multi-element Synthetic Transmit Aperture Method for Medical Ultrasound Imaging Applications

Tasinkevych¹,

Trots²,

Nowicki³

et al. 2012

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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.

“…In (Mechel, 1995) the effect of absorption in the near-field and reflection directivity in the far field were described. Sound pressure distribution of the reflected wave can also be computed by the inverse Fourier transform from their spatial spectra on the diffuser's plane, using a method developed in electrostatics (Tasinkevych, 2010).…”

Section: Effect Of Materials and Construction On The Sound Absorption mentioning

confidence: 99%

The Effect of Geometrical and Material Modification of Sound Diffusers on Their Acoustic Parameters

Pilch¹,

Kamisiński²

2011

Sound diffusers, in particular those based on changes in the phase of the reflected wave (Schroeder diffusers), have recently gained greatly in popularity in acoustics as an effective means to eliminate defects and improve the acoustic performance of interiors. This paper draws attention to a possibility of shaping acoustic parameters of sound diffusers and fundamental errors made in applying diffusers. Also, an often neglected issue of sound absorption by diffusers has been tackled. The presented results of laboratory measurements indicate a great significance of the diffusers' rigidity and geometry on their absorption coefficient at low frequencies. The effect of arrangement of elements on the diffusion coefficient was analysed for two types of elements based on the prime number N = 7.