The initial pressure and speed of sound (SOS) distributions cannot both be stably recovered from photoacoustic computed tomography (PACT) measurements alone. Adjunct ultrasound computed tomography (USCT) measurements can be employed to estimate the SOS distribution. Under the conventional image reconstruction approach for combined PACT/USCT systems, the SOS is estimated from the USCT measurements alone and the initial pressure is estimated from the PACT measurements by use of the previously estimated SOS. This approach ignores the acoustic information in the PACT measurements and may require many USCT measurements to accurately reconstruct the SOS. In this work, a joint reconstruction method where the SOS and initial pressure distributions are simultaneously estimated from combined PACT/USCT measurements is proposed. This approach allows accurate estimation of both the initial pressure distribution and the SOS distribution while requiring few USCT measurements.

中文翻译：

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通过组合光声和超声断层扫描测量联合重建声音分布的初始压力和速度

仅通过光声计算机断层扫描 (PACT) 测量无法稳定地恢复初始压力和声速 (SOS) 分布。辅助超声计算机断层扫描 (USCT) 测量可用于估计 SOS 分布。在组合 PACT/USCT 系统的传统图像重建方法下，仅根据 USCT 测量值估计 SOS，并使用先前估计的 SOS 根据 PACT 测量值估计初始压力。这种方法忽略了 PACT 测量中的声学信息，可能需要多次 USCT 测量才能准确重建 SOS。在这项工作中，提出了一种联合重建方法，其中 SOS 和初始压力分布是根据组合的 PACT/USCT 测量同时估计的。这种方法可以准确估计初始压力分布和 SOS 分布，同时需要很少的 USCT 测量。