Plane wave beamforming with adaptively weighted frequency compound using bandpass filtering

Abstract

We previously proposed the frequency and plane-wave compounding minimum variance distortion-free response (FPWC-MVDR) beamformer for ultrasonic reception beamforming, which weights the transmission angle and frequency band adaptively. This method required multiple subband transmissions and receptions for each transmission angle, reducing the frame rate. Here, we propose a filtered-FPWC-MVDR method that extracts and uses subband components via signal processing from the echo received after a single wideband pulse transmission. After confirming that this method provides the same performance as the original FPWC-MVDR, we experimentally investigate the subband conditions required, i.e. the bandwidth and number of subbands, when using this method. As a result, to improve the point target resolution, we find that there is an appropriate subbandwidth condition involving a trade-off between ensuring echo localization and increasing the degrees of freedom for frequency weight determination. Additionally, for improved contrast, the subbands were arranged appropriately to cover the entire usable frequency band.

Evaluating a 3D Ultrasound Imaging Resolution of Single Transmitter/Receiver with Coding Mask by Extracting Phase Information

“…After applying the IQ detector, the solution- x was computed numerically for each subband and angle of rotation, resulting in -images (tensor data X ). The weighted frequency subband compound was applied to the second-order tensor data X by following the minimum-variance distortion-free response (MVDR) method [ 31 ]. The details of MVDR can be clearly seen in Appendix A .…”

“… where denotes the pixel value at subband- i and angle- j . Following [ 31 ], the frequency subbands compound is started by computing the variance covariance matrix- R that requires the following vector , and matrix R is given by where H indicates Hermitian transpose, is diagonal loading parameter, and I represents an identify matrix. The number of rotation angles N is required for averaging matrix- R as well as for averaging the frequency subbands.…”

One-shot beam-forming with adaptively weighted compound of multiple transmission angles and subbands

“…In the original FPWC-MVDR, 25) subband transmission and reception are performed L times for each angle. In filtered FPWC-MVDR, 26) to improve the frame rate, the transmission and reception of all bands are performed at once for each angle, and the subband echo is extracted from the obtained echo using signal processing. In the following, filtered FPWC-MVDR is simply called FPWC-MVDR, and its improvements are described.…”

“…Thus, to improve the frame rate, we developed a filtered FPWC-MVDR beamformer that transmits a wideband plane wave only once at each angle and divides the received echo into multiple subbands for processing. 26) We can mitigate the drawback of adaptive beamforming complexity by further reducing the number of transmissions and receptions. In this study, we propose a new beamformer that requires only one transmission and reception, while suppressing the deterioration of image quality.…”

Subband compound with fundamental wave and harmonics in focus wave beamforming

“…[15][16][17][18] Concurrently, for fundamental imaging, we proposed filtered frequency and plane-wave compounding minimumvariance distortion-free response (MVDR) beamforming, which transmits and receives the entire effective band all at once, and then extracts multiple narrow subbands by frequency filtering. 19) Next, from the MVDR, the adaptive frequency weight of each subband is calculated. Furthermore, for each angle of the subbands and its adaptive frequency weight, the adaptive angle weights are calculated.…”