Research Of Tissue Harmonic Imaging Based On Pulse Inversion Technique

Harmonic imaging technology was originally developed for ultrasound contrast imagingwith the rapid development of computer,electronic technology and other high-tech technology.It was found that the organization of the human body can produce the harmonic signal and the signal can beused for imaging.So tissue harmonic imaging is proposed.This technology applied in imaging can obtain higher resolution and contrast,improve the quality of ultrasound images.At present,the most advanced ultrasound diagnostic instrument has the functions of tissue harmonic imaging.However,there are two factors affect the quality of the harmonic imaging.First,the control of fundamental wave bandwidth may cause fundamental wave and harmonic bandwidth over lap.Harmonic signal will be swamped by high intensity of fundamental wave and it will cause the quality loss of harmonic image;Secondly,harmonic intensity is relatively low wave.Its low signal-to-noise ratio will be harmful to imaging.So in recent years how to further improve the quality of harmonic imaging and its application of clinical diagnosis become important subjects.This paper mainly studied the application and advantages of the pulse reverse phase technique in tissue harmonic.First application of acoustic simulation based on MATLAB toolkit k-wave.It will built entire system simulation on harmonic imaging theory,gets the RP simulation data,and do signal processing.Extracting harmonic signal with the method of band filter and the method of pulse reverse phase to get the signal with second harmonic frequency.After filtering,the signal will be managed by enevlope detection,log compression and digital scan conversion.Then the final images will be displayed on the screen.Quality of different images are judged by resolution and contrast ratio.The next step is the treatment and observation the real data of ultrasound probes,which is collected in the ultrasound laboratory of Neusoft Medical.The last is the hardware of preliminary design for launch of ultrasonic and pulse filter demodulation of echo signal,using Xilinx System generator toolbox.By comparing three images of different ways,it prove the advantageof pulse reverse phase method.