Large depth focus-tunable photoacoustic tomography based on clinical ultrasound array transducer

• Published in: Applied physics letters 2018-10, Vol.113 (14)
• Main Authors: Liu, Ruian, Xiang, Liangzhong, Xing, Da, Li, Jiandong, Qin, Huan, Zhang, Weicheng, Yang, Sihua
• Format: Article
• Language: English
• Subjects: Applied physics; Carbon; Depth of field; Image resolution; Laser arrays; Laser beams; Medical imaging; Nanoparticles; Photoacoustic effect; Signal processing; Tomography; Ultrasonic imaging
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.5040565

Multi-element photoacoustic tomography systems have either a non-movable focus or a non-uniform light field distribution over the region of interest, significantly limiting the depth-of-field and resolution of images. In this study, focus-tunable photoacoustic tomography (FT-PAT) based on a clinical ultrasound array transducer with uniform laser excitation was developed to achieve high-resolution imaging in deep tissue. An adjustable line-focusing structure was used to condense the laser beam, and the excited photoacoustic signal was processed via a synthetic-aperture focusing technique. Carbon rods at different depths were used to evaluate the focus-tunable ability in a tissue phantom. In vivo focus-tunable imaging performance was demonstrated by an experiment involving imaging of carbon nanoparticle-labeled living nude mouse covered by chicken breast. The signal-to-noise ratio of targets at different depths was changed by focus adjustment, which demonstrates that the FT-PAT system has potential clinical applications in deep tumor imaging and subsequent diagnoses.