Research Of Photoacoustic Imaging Technology And Its Experiment

Computed tomography(CT), ultrasonic imaging, positron emission tomography(PET) and Magnetic resonance imaging（MRI）, as four of medical imaging technologyhas been national concern and has been rapid development. But they all have their ownadvantages and disadvantages. In recent years, there has been a high sensitivity ofnondestructive testing technology, Called Photoacoustic Tomography (PAT). PATcombines advantages of both ultrasound and optical imaging, can provide highultrasonic resolution and high optical cantrast tissue images. So it can serve as animportant means to study the structure and function information of the biological tissue.In recent years, this technology has been the attention of the world and has been therapid development. Many people have gat better results that use PAT for brain imaging,breast cancer detection, osteoarthritis detection and oxygen saturation of the bloodvessel detection. In this paper, we mainly research the selection and the design of thehardware in the ring photoacoustic scanning system, the impact factors of thereconstructed image quality, the technologies of PAT and the experiments. It mainlyconsists of the following parts.(1) Described the technical principles and the selection of the main devices of theannular scanning photoacoustic imaging system; Designed a small-signal amplifier forthis system and by doing experiments to verify its practicality; Discussed severalphotoacoustic imaging reconstruction algorithms and selected delay-sum algorithm forour photoacoustic imaging system.(2) The frequency of the signal generated by the different dimensions of absorbentbody has been studied; the effects on reconstructed image by the transducer apertureangle and its center frequency has been studied; The scanning step of the transducereffects on the quality of the reconstructed images has been studied; The relationshipbetween the scanning path and the orientation of the absorber effects on the quality ofthe reconstructed images for the limited-view scanning have been studied. We obtainedthat the corresponding center frequency of the transducer should be selected accordingto the absorbent body; we obtained that the scanning Angle of transducer is larger and the step size is smaller, the resulting image is more clear.(3) The CT image reconstruction has been discussed, and we used it in the ringscanning photoacoustic imaging system. We used experimental to verify its feasibility.Compressed sensing and total variation denoising model have been discussed, and weused it in the ring scanning photoacoustic imaging system. Simulation results arepresented to demonstrate that this method can realize the detection of a single point ofthe sample.(4) We analyzed the relationship between the shape of the photoacoustic signalwaveform and the absorbent body. We compared the reconstruction images ofphotoacoustic and thermoacoustic tomography, which laid the foundation for futuremulti-modal imaging and image fusion.