Resrarch On Digital Endoscopic Ultrasound Color Flowing Mapping System

Medical endoscopic ultrasound diagnosis, with the advantanges of painless, harmless, non-ionizing, has been widely used in evaluation of the dynamics of peripheral arteries and veins. Endoscopic Ultrasound Color Flowing Mapping System(EUS-CFM System), combines the advantage of ultrasound in diagnosis and the sensitivity of Doppler to moving objects together. It can detect the flow of blood in organs to obtain the direction, velocity and other information of the blood.EUS-CFM System captures the weak signal scattered from tissue. An all-digital signal processing method is proposed in this paper, referring to Pulse Ultrasound Doppler System which our group has researched. The analog front-end circuits and digital signal processing board have been designed for EUS-CFM system. Field Programmable Gate Array (FPGA) is used for system timing control and digital signal processing. Also, the experiment platform based on the Doppler physical model was set up to verify the performance of the system.The main work is listed below.Firstly, all-digital signal processing method for EUS-CFM system is proposed based on FPGA. Rotated scanning imaging simulation was made with the help ofFieldⅡ, which is a dedicated ultrasound imaging simulation software. Secondly, the analog front-end circuit and digital circuit were designed for the acquisition and processing of Doppler ultrasound echo signals. The PCB of pre-amplifier circuit, anti-aliasing filter circuit and six-layer digital signal processing circuit were designed and debugged.Thirdly, program of FPGA was written and compiled in Quartus II, using Verilog HDL. System timing control and module design were implemented in FPGA, with the realization of demodulation, wall filtering and auto-correlation.Lastly, the Doppler physical experiment platform was set up, with eristaltic pump, simulated blood flow and blood vessels as main components. The experiments of blood flow velocity detection was made to verify the correctness and effectiveness of EUS-CFM system. The system design and signal processing method are proved reasonable and correct by the experiment results of blood flow velocity curve.