Phase-insensitive versus phase-sensitive ultrasound absorption tomography in the frequency domain

TL;DR

This paper compares phase-insensitive and phase-sensitive ultrasound absorption tomography using numerical models to evaluate their effectiveness in sparse detector configurations, highlighting the potential advantages of phase-insensitive sensors.

Contribution

It introduces measurement models for both sensor types and assesses their performance in absorption tomography with sparse detectors through numerical simulations.

Findings

Phase-insensitive sensors maintain omni-directionality at large sizes.

Phase-sensitive sensors become more directional with larger elements.

Sparse phase-insensitive sensors can produce comparable image contrast to phase-sensitive ones.

Abstract

The sensitivity of phase-sensitive detectors, such as piezoelectric detectors, becomes increasingly directional as the detector element size increases. In contrast, pyroelectric sensors, which are phase-insensitive, retain their omni-directionality even for large element sizes, although they have significantly poorer temporal resolution. This study uses numerical models to examine whether phase-insensitive detectors can be used advantageously in ultrasound tomography, specifically absorption tomography, when the number of detectors is sparse. We present measurement models for phase-sensitive and phase-insensitive sensors and compare the quality of the absorption reconstructions between these sensor types based on image contrast metrics. We perform the inversion using synthetic data with a Jacobian-based linearised matrix inversion approach.