open-UST: An Open-Source Ultrasound Tomography Transducer Array System

TL;DR

This paper introduces open-UST, an affordable, open-source ultrasound tomography transducer array system with comparable performance to commercial systems, enabling broader research and development in UST imaging.

Contribution

The work presents a novel, low-cost, open-source 256-element transducer array for UST, manufactured with rapid prototyping and validated through performance measurements and phantom imaging.

Findings

Achieved a mean beam axis skew of 1.17° and element position error of 104 μm.

System demonstrated 61.2 dB SNR and 55.4° opening angle, similar to existing systems.

Successfully reconstructed phantom data, confirming system usability.

Abstract

Fast imaging methods are needed to promote widespread clinical adoption of Ultrasound Tomography (UST), and more widely available UST hardware could support the experimental validation of new measurement configurations. In this work, an open-source 256-element transducer ring array was developed (morganjroberts.github.io/open-UST) and manufactured using rapid prototyping, for only {\pounds}2k. Novel manufacturing techniques were used, resulting in a 1.17$^{\circ}$ mean beam axis skew angle, a 104 $\mu$m mean element position error, and a $\pm$13.6 $\mu$m deviation in matching layer thickness. The nominal acoustic performance was measured using hydrophone scans and watershot data, and the 61.2 dB SNR, 55.4$^{\circ}$ opening angle, 16.3 mm beamwidth and 54% transmit-receive bandwidth (-12 dB), were found to be similar to existing systems, and compatible with full waveform inversion reconstruction methods. The inter-element variation in acoustic performance was typically <10% without using normalisation, meaning that the elements can be modelled identically during image reconstruction, removing the need for individual source definitions based on hydrophone measurements. Finally, data from a phantom experiment was successfully reconstructed. These results demonstrate that the open-UST system is accessible for users, and suitable for UST imaging research.