The Design And Experimental Study Of Ultrashort Pulse Thermoacoustic System

Medical image mining has been one of the fastest developments of medical technology, and it provides scientific foundation of clinical diagnostics and biomedical research, Tomography is composed of radiography, X-CT, MRI, supersonic diagnosis, nuclear medicine, and EM infrared photography. Now ultrasonic diagnosis, together with X-CT, NMR and nuclide scan, have already become the four major imaging techniques in modern image medicine. Nevertheless,these known methods all have their own limits and drawbacks. Scientists are pioneering new technologies and offering new solutions while improving the traditional medical imaging technology.Thermoacoustic imaging technology induced by ultra-short pulse of microwave,which is a new type biomedical detection and imaging technology, as non-invasiveness function imaging. Using ultra-short pulse microwave irradiate tissue samples with electromagnetic wave absorption differences, Ultrasonic signals will be operated through thermoacoustic principles;So generated ultrasonic signals carry the large amounts of information of the sample, Finally, the collected sound signal based on the tissue sample reconstruct the absorption distribution image. This imaging technology shows the high resolution of the ultrasonic image and with high perforated depth and the high contrast of microwave imaging. Compared with traditional microwave thermoacoustic imaging technology,this method further reduces microwave radiation doses, improves the image resolution and reduces the microwave thermal damage.This article focused on the theory of ultra-short pulse microwave thermal imaging technology,the system design and experimental research. Several aspects content are included in this paper as following:1、In the first part of this article, we introduce the development, current situation and application of the thermoacoustic imaging technology and the research background and tasks of this article. Describes the development and the situation of commonly used medical imaging technology. At the same time, the advantages and limitations of these technique were discussed as well. This paper mainly analyses characteristics and superiority of the ultrashort pulse thermal imaging technology, futuredevelopment and application perspective are also given.2、Analyzes the basic theory of ultra-short pulse thermal imaging technology. The thermoelastic excitation equation and the equation of TA signals from the Gaussian pulse are studied. The generation reasons and influences of the TA signals, acoustic wave energy attenuation, and electromagnetic spreading regulation have been verified by experiments and theoretical analysis. On the base of simulation, it has been testified the feasibility of ultrashort microwave thermoacoustic imaging.3、Ultra-short pulse signal simulation, The signal waveform based on different pulse duration was analyzed, and the imaging resolution are investigated based on the effect of microwave pulse width. Simulation results show, this technique has a high thermal-acoustic conversion efficiency and a high resolution.4、This paper designs a ultra-short pulse microwave antenna, Through computer simulation system design and simulation of the antenna, numerical results of analysis and optimization show that this antenna can be used in ultra-short pulsed microwave generator, and reached the design requirements.5、The design of the experimental system and research on experiments has been completed, the system hardware composition and the experimental results is presented. Through the analysis of experiment results analyze the quality of the images and the critical influences.