Joint reconstruction of the sound speed and initial pressure distributions for ultrasound computed tomography and photoacoustic computed tomography

Abstract

Accurate reconstruction of the initial pressure distribution in photoacoustic computed tomography (PACT), in general, requires knowledge of the sound speed distribution of the medium. However, the sound speed distri- bution is often unknown, and estimating both the sound speed and initial pressure from PACT measurements alone is unstable. An alternative is to estimate the sound speed from ultrasound computed tomography (USCT) measurements. This approach fails to exploit the acoustic information in the PACT measurements and may require many USCT measurements to accurately reconstruct the sound speed. Here, we propose a joint recon- struction method where the sound speed and initial pressure distributions are simultaneously estimated from combined PACT/USCT measurements. This approach effectively overcomes the instability of the PACT joint reconstruction problem while requiring few USCT measurements.