Model-Based Reconstruction for Collimated Beam Ultrasound Systems

TL;DR

This paper introduces a physics-based, model-driven iterative reconstruction algorithm for collimated beam ultrasound systems, significantly improving image accuracy in complex multi-layered media over traditional methods.

Contribution

It presents a novel multi-layer, model-based iterative reconstruction method that accurately models ultrasonic propagation and reduces artifacts in collimated beam ultrasound imaging.

Findings

Fewer artifacts compared to delay-and-sum methods

Achieves near real-time performance with commodity hardware

Validated with simulated and experimental data

Abstract

Collimated beam ultrasound systems are a novel technology for imaging inside multi-layered structures such as geothermal wells. Such systems include a transmitter and multiple receivers to capture reflected signals. Common algorithms for ultrasound reconstruction use delay-and-sum (DAS) approaches; these have low computational complexity but produce inaccurate images in the presence of complex structures and specialized geometries such as collimated beams. In this paper, we propose a multi-layer, ultrasonic, model-based iterative reconstruction algorithm designed for collimated beam systems. We introduce a physics-based forward model to accurately account for the propagation of a collimated ultrasonic beam in multi-layer media and describe an efficient implementation using binary search. We model direct arrival signals, detector noise, and a spatially varying image prior, then cast the reconstruction as a maximum a posteriori estimation problem. Using simulated and experimental data we obtain significantly fewer artifacts relative to DAS while running in near real time using commodity compute resources.