Photoacoustic computed tomography by using a multi-angle scanning fiber-laser ultrasound sensor

Photoacoustic computed tomography (PACT) can ultrasonically image optical absorbers in biological tissues by using a linear piezoelectric transducer array, but some features can not be visualized as a result of the limited acceptance angle. The optical ultrasound sensors for photoacoustic imaging have received great interests, because of their compact sizes, comparable sensitivities to their electric counterparts, as well as the extended field/angle-of-view. In this work, we have developed a PACT system based on a fiber-laser based ultrasound sensor. Two-dimensional imaging was performed by horizontally scanning the sensor and image reconstruction via back projection, and three-dimensional imaging was further achieved by repeating such scanning process at multiple angles, based on inverse Radon transform. The axial and lateral resolutions are 93 and 220 μm in three-dimensional imaging. Taking advantage of the dual-60-degree vision angles, more features, especially horizontal structures, can be resolved.