Research Of Signal Transmission System And Processing System Of Real-Time Phased Array Ultrasonic Endoscope

The development of science and technology promotes the continuous progress of the medical industry.Medical endoscopic ultrasonography(MEUS)combines traditional endoscopy with ultrasonography.It uses the characteristics of safety,non-invasiveness and accuracy of ultrasound imaging technology to detect diseases in patients in time,so as to achieve early detection and treatment.The common endoscopic ultrasonography system consists of a single array ultrasonic endoscopy system and a phased array endoscopic ultrasonography system.Compared with traditional single-element ultrasound system,phased array ultrasound system has higher imaging resolution and better image quality,and is widely used in domestic hospitals.The research difficulties of phased array endoscopic ultrasound system are as follows: the increase of the number of transducer elements can improve the quality of ultrasound image,but the amount of calculation data also increases,which makes the hardware architecture of endoscopic ultrasound system more complex and more difficult to develop;at present,the commonly used ultrasound imaging algorithm is synthetic aperture algorithm.But it has the disadvantages of serious side lobe noise and slow imaging speed.To solve these problems,a 64-element real-time phased-array endoscopic ultrasound imaging system is designed in this paper,which includes four parts: transmitting module,receiving module,transmitting module and ultrasonic imaging algorithm.The imaging experiments using simulation data and actual echo data show that the system built in this paper is feasible,and the proposed algorithm has real-time and high efficiency.The major work of this thesis can be summarized as these seven parts:1.The design of phased-array ultrasound imaging system at home and abroad was investigated,and 64-element medical phased-array ultrasound endoscopy system was designed.2.The project design of medical phased-array endoscopic ultrasound transmitter module is completed.The functions of high-voltage pulse generation,transducer excitation,element selection and high-precision signal delay are realized by programming with FPGA.3.The scheme design of medical phased-array endoscopic ultrasound receiving module is completed,and the pre-processing module is built with AD9272.The functions of high-voltage limiting,signal amplification,gain control,band-pass filtering and analog-to-digital conversion are realized.4.The project design of medical phased-array endoscopic ultrasound transmission module is completed,and the echo data is uploaded to the host computer at high speed through PCIe3.0 bus.5.A Coherence-Based Synthetic Aperture Beam Forming(CFSA)algorithm based on coherence coefficients is proposed.By introducing coherence coefficients,the suppression effect of synthetic aperture algorithm on sidelobe noise is improved and the quality of echo image is improved.6.Using CUDA to parallelize CFSA algorithm and GPU to accelerate the algorithm,the algorithm can meet the real-time requirements of medical endoscopic ultrasound system.7.Based on the completion of each sub module,a 64 phased array endoscope system is built.The feasibility of the system is verified by imaging the samples of iron wire and pig skin.