Spherical Design And Implementation Of Focused Ultrasound High-precision Phase Control Signal

High-precision phased signals play an important role in spherical focused HIFU (high intensity focused ultrasound, HIFU) therapy, its accuracy directly affects the sound field and the sound field gain of HIFU focal area. The larger its error is, the smaller the sound field gain is, and the greater the bias of corresponding sound field strength, thus affecting the final treatment of the HIFU therapy.The design difficulties of the phased signals of spherical focused HIFU mainly include its high precision and excessive output channels. The accuracy of the normal clock count method is determined by the clock frequency, the higher accuracy we need, the higher the clock frequency we must take, and high clock frequency will lead to too much power consumption; besides, in order to get higher accuracy, selectors are needed to trigger the output by selecting the different phased clocks, and the uncorrelated delay paths of its input signals would affect the stability of output phased signals.The digital cursor measurement is usually used to improve the measure accuracy of the cycle and time interval, whose measure accuracy is determined by the difference of cycles between the standard clock pulse and the cursor clock pulse, the smaller the difference is, the higher the accuracy will be, so it not only increases the measure accuracy, but also reduce the clock frequency. Base on the digital cursor measurement, this thesis proposed a method, the digital cursor phased method.The FPGA becomes the ideal chip in the process of designing phased signals because of its rich clock resources and GPIO resources. Base on FPGA and the method we proposed, we can design and realize the phased signals of the spherical focused HIFU. For practical applications of spherical phased array focused ultrasound transducer (SPAFUT), we expanded the relevant communication and control module and signals driver module, finally we built a high-precision phase control system of SPAFUT.After circuit design, PCB layout, software design and other steps, the prototype of the high-precision phase control system was constructed based on the designed different modules. The test results of the prototype show that the proposed methods and techniques in this thesis can be used in the SPAFUT. The test results also show that the works of this thesis are of important signification for the further study of the SPAFUT.