Rearch On Pulsed Doppler Ultrasonic Endoscope System

Medical Doppler diagnosis has attracted much attention during these years due tothe rapid development of digital signal processing, hardware and software design,micro electronics, mechanics and material science. As an aid to vascular diseasediagnosis, Doppler Ultrasound has been widely used in evaluation of the dynamics ofperipheral arteries and veins. Medical Doppler ultrasonic endoscope is designed basedon ultrasonic endoscope system, combining the advantage of ultrasound in diagnosisand the sensitivity of Doppler to moving objects together. As the distance between theprobe head and organ was shorter, thus limiting the effect of body cavity gas and fat,so it can get much more detailed information than the image obtained from thescanning on the surface of body. As a result, the capacity of early diagnosis can beenhanced, and also the operation is convenient.The main work of this paper is listed below:Firstly, different methods of analyzing and distilling Doppler frequency shiftinformation were investigated. Single sideband separation, demodulation andquadrature demodulation were compared, and then quadrature demodulation wasselected to attain the information of blood direction and rate.Secondly, based on the original B ultrasound endoscope system designed in ourlaboratory, new Doppler system was designed with the adding of echo signalquadrature demodulation, wall filtering and spectrum analysis module, all achievedfrom FPGA.Thirdly, several different kinds of Doppler blood echo data access methods wereanalyzed. Utilizing the echo signal from computer software simulation, progress ondealing with echo signals was debugged, and the satisfactory result was obtained, thefitting water model was used to debug the Doppler ultrasonic endoscope system.Lastly, through debugging circuit, the satisfactory result was input into acomputer through the USB, Doppler dynamic power spectrum was got and thepurposes of pulse Doppler detection was realized.