Research Of Signal Reception System Of Phased Array Ultrasonic Endoscope

The endoscope ultrasound system(EUS)imaging technology for medical diagnosis plays an important role in the detection of human body and other parts of the digestive tract because of its non-destructive,painless and unique ability to probe the mechanical properties of tissue.There are two commonly used ultrasound endoscopy systems,ring scan endoscopic imaging system and phased array ultrasound endoscopic imaging system respectively.Compared with ring scan endoscopic imaging system,phased array ultrasound endoscopic imaging system has three advantages.First,use electron beam focusing and scanning without the case of rotating the transducer to achieve tissue scan.Second,achieve the ultrasonic beam spatial synthesis even in the low driving voltage and get a strong sound field strength of the scanning signal.Third,control the focus size,focus depth and beam deflection direction flexibly.At present,main difficulties in the research of phased array ultrasound endoscopic imaging system is the large amount of data computation and the large amount of data storage,which makes it difficult to meet the real-time requirement.When the number of elements of transducer increases,the complexity of hardware architecture of signal receiving system increases therewith.According to problems above,a signal receiving system based on integrated analog front AD9272 is implemented.In this paper,the analog pre-treatment circuit and the signal receiving circuit are designed and the controlling programs of FPGA are completed.It has bend proved that the system is stable by experiments.Besides,a new algorithm used in phased array ultrasound endoscopic system is proposed.It can improve the SNR and resolution of ultrasound image.The main work of this paper is listed below:1.Design the signal receiving system of phased array ultrasound endoscopic based on integrated analog front AD9272.The system realizes the synchronous computation,storage and transmission of multi-channel echo signals,which satisfies the condition of real-time.2.Complete the design analog pre-treatment circuit and signal receiving circuit in signal receiving system,including FPGA and peripheral circuits,power management,SPI controller,DDR2 memories and so on;Use Verilog to complete the program of FPGA,which can realize the function of receiving and transferring echo signals.3.Set up the testing system of phased array ultrasound endoscopic and test the functions of signal receiving system successfully,which verifies the correctness and feasibility of the system.4.Propose an imaging algorithm of phase array ultrasound endoscopic based on coded excitation.The algorithm improves the SNR and resolution of ultrasound image.Use Matlab to make the simulation of algorithm and the result of simulation proves the feasibility of algorithm.