High resolution ultrasonic imaging based on frequency sweep in both of transducer element domain and imaging line domain

Abstract

We developed the super resolution FM-chirp correlation method (SCM) and its high frame rate version called synthetic aperture-SCM (SA-SCM) based on frequency sweep in order to improve the range resolution in ultrasound imaging. However, in these methods, discontinuities in the lateral direction tend to occur, because the SCM processing is performed line by line in the image. In addition, in array transducers, grating lobes are more likely to occur when the spatial resolution is increased using high-frequencies. Therefore, another version called SCM-weighted SA was proposed. In the SCM-weighted SA, in order to avoid the lateral discontinuities, first the SCM processing is performed on each echo received by each transducer element, and then the obtained SCM result is used as a weight for SA processing. The SCM-weighted SA can generate multiple B-mode images each of which corresponds to each carrier frequency, and the appropriate low frequency images among them have no grating lobes. While this plurality of B-mode images can be used as multi-frequency images, it can also be integrated as one high SNR image. In the present study, we propose a method to generate the integrated one B-mode image by applying SCM again in the line direction of the obtained multi-frequency images, which is called SCM-weighted SA-SCM. This method can further improve the range resolution.

Plane wave beamforming with adaptively weighted frequency compound using bandpass filtering

“…In addition, although the filtered-FPWC-MVDR method was constructed in the time domain in this paper, efficiency consideration are currently driving reconstruction of this method in the frequency domain with reference to the method in the literature. 14) Previously, we have studied methods to detect the positions of a small number of reflectors with high resolution [24][25][26][27][28] and these methods were suitable for use in anomaly detection applications such as tumor imaging. The technical feature of these methods involved realizing the required resolution at the wavelength level of the carrier by using various frequencies for both transmission and reception.…”

Subband compound with fundamental wave and harmonics in focus wave beamforming

“…[1][2][3] With the latter, the use of high frequencies is still inevitable. 4,5) With the higher frequencies that are transmitted and received, a problem arises in designing the ultrasound equipment because they also become very complicated. [6][7][8] Early ultrasound imaging techniques are based on the linear theory of acoustics.…”

Acoustic sensing method for an occlusion area with super-directional sound sources and multiple modulation signal

“…Sensing systems have been developed to exploit these physical characteristics. [7][8][9][10][11][12][13] This study focuses on diffraction phenomena. Sound waves in the audible range have a relatively longer wavelength in comparison to ultrasound waves.…”