Fast Photoacoustic Imaging System Based On Multi-element Transducer Array

First, an USB high-speed data acquisition card based on the LabVIEW platform was designed. Conformed to USB 1.1 protocol, it can support high-speed data transfer up to 12Mb/s. The card was characteristic with anolog digit converting with high sample rate of 24MS/S and high-speed counter, belong to this, it can implement as common IO. Hardware and software of the card are mainly discussed, and the method to call DLL in LabVIEW and the way to design an USB driver are given in this paper. The card has been applied in our single photon counter cell function analyzer for automatic detection. This analyzer can detect the ultra-weak luminescence sensitively and comparably.Then, a multi-element linear transducer array system based on the high-speed data acquisition card was designed and realized photoacoustic imaging by it firstly. Compared to other existing technology and algorithm, the PA imaging based on transducer array was characterize by speediness and convenience. It can provide a new approach for tissue functional imaging in vivo, and may have potential in developing into an appliance for clinic diagnosis.Finally, a fast photoacoustic (PA) imaging system setting based on multi-element linear transducer array system was developed and tested on tissue phantoms. A Q switched Nd:YAG laser operating at 532nm was used in our experiment as thermal source. The multi-element linear transducer array consists of 320 elements. By phase-controlled method, 64 signals, one of which gathered by 11 -group element, make up of an image. Phantom experiment results mapped the distribution of the optical absorption correctly. A makeup of the multi-element linear transducer array system and Experimental setup were described in detail, besides the application of phase-controlled algorithm in multi-element transducer array. The transducer array also can produce conventional ultrasound images. In addition, photoacoustic imaging combining ultrasonic imaging was developed and tested, which provided more information for biological tissue functional imaging. In addition, affection for imagingof different frequency band PA was discussed. When the frequency range of transducers accords to that of absorbers, almost whole frequency component of photoacoustic pressure can be detected. That results in good reconstructed images. So the ultrasonic transducers used to detect photoacoustic pressures should be designed and selected according to the frequency ranges of absorbers.In conclusion, fast acquisition for anolog and digital signals was realized by USB interface technology, and was applied in experimental instruments. The cell function analyzer based on the USB data acquisition card will apply in the detection of the cell luminescence and some correlated clinical assay widely, and the multi-element transducer array system based on the same card has the same potential application approach in the biological tissue photoacoustic imaging and noninvasive detector.