Research And Application Of Ultrasonic Harmonic Imaging Based On Pulse Flip

In the field of ultrasonic medical, harmonic imaging solved the imaging problems caused by obesity, rib space narrowing, abdominal wall thickness of patients. It greatly improved the accuracy of clinical diagnosis. Compared with the traditional ultrasonic imaging, the imaging effect of harmonic imaging is better on abdominal viscera, cardiovascular tissue and improved the accuracy to check of such tissues. At present, the harmonic imaging as one of the advanced imaging models of ultrasound image diagnosis, its research is lacking, its imaging quality is still restricted to the shortage of the equipment system performance and the related technology is not mature.In this paper, on the basis of in-depth study of ultrasonic harmonic imaging technology, we use the method of pulse flip to weaken the tissue fundamental wave signal, and enhance the harmonic signal of ultrasound contrast agents micro-bubble to suppress the residual fundamental wave signal of tissue. It can improve harmonic and tissue signal power ratio(STR) to improve the image resolution. On the basis of pulse flip superposition method, through analysis and verification, it uses the sequence pulse flip superposition method, which makes up the defect of the former accuracy. It’s effect to eliminate the tissue fundamental wave signal is more obvious. Images through the experiment results show that the sequence pulse flip superposition method could get the higher resolution of the image than regular pulse flip superposition method.The design of high frequency ultrasound harmonic imaging system, uses C yclone V series of 5CGXFC7D7F31C8 N model FPGA chip as its core article to realize the digital signal processing. In order to improve the stability and reliability of the system circuit, it adopts the design concept of miniaturization, integration, low noise. The high-speed parallel digital signal processing characteristic of FPGA makes the system real-time performance improved. System structure according to the function is divided into signal transmitting circuit, echo signal receiving and converting circuit, signal acquisition and processing circuit, data transmission module. In order to meet the different needs, software algorithm adopts modular design to be easy to upgrade and system expansion. Software is written in VHDL language, embedded into the FPGA. The software system includes the signal driving module, echo signal processing module and the data transmission module.This study has set up an experimental platform for the simulation of intravascular blood flow. Experiments are operated with the high-frequency ultrasonic harmonic imaging system, whose design is based on FPGA. Through the harmonic image in blood vessels, it can prove pulse flip superposition method in eliminating the tissue fundamental wave signal has a very good result, which gets the better image resolution than ever before. At the same time, it also verifies the sequence pulse flip superposition method can get the better STR and signal-to-noise ratio, the image resolution has improved further.