Patch Based Transformation for Minimum Variance Beamformer Image Approximation Using Delay and Sum Pipeline

TL;DR

This paper introduces a patch-based U-Net neural network approach to approximate minimum variance beamforming images from delay and sum data, aiming for real-time performance with less data.

Contribution

It proposes a novel patch-level neural network method that models the beamforming process as a non-linear image transformation, reducing data requirements and improving efficiency.

Findings

Effective approximation of MVDR images using patch-based U-Net.

Reduced dataset needs compared to image-level learning methods.

Potential for real-time beamforming in practical applications.

Abstract

In the recent past, there have been several efforts in accelerating computationally heavy beamforming algorithms such as minimum variance distortionless response (MVDR) beamforming to achieve real-time performance comparable to the popular delay and sum (DAS) beamforming. This has been achieved using a variety of neural network architectures ranging from fully connected neural networks (FCNNs), convolutional neural networks (CNNs) and general adversarial networks (GANs). However most of these approaches are working with optimizations considering image level losses and hence require a significant amount of dataset to ensure that the process of beamforming is learned. In this work, a patch level U-Net based neural network is proposed, where the delay compensated radio frequency (RF) patch for a fixed region in space (e.g. 32x32) is transformed through a U-Net architecture and multiplied with DAS apodization weights and optimized for similarity with MVDR image of the patch. Instead of framing the beamforming problem as a regression problem to estimate the apodization weights, the proposed approach treats the non-linear transformation of the RF data space that can account for the data driven weight adaptation done by the MVDR approach in the parameters of the network. In this way, it is also observed that by restricting the input to a patch the model will learn the beamforming pipeline as an image non-linear transformation problem.