Investigation Of Acostic Field And Lesion In Tissue In Vitro For Dual-Frequency Focused Concave Spherical Transducer

High intensity focused ultrasound(HIFU) treatment have been used in sorts of tumor and non-tumor disease.The tissues of target region would absorb the energy of the supersonic wave and be destroyed,while the tissues out of the target region would not be destroyed.But during the tumor therapy especially those deeply located in body or with a large volume, HIFU was a time-consuming therapeutic method and the curative effect was far from ideal.It was researched that how to enhancement the therapeutic efficiency of HIFU by a variety of ways in international.One of the effective ways is developing new transducer.Traditional HIFU transducer works as the mode of single frequency. Some researches show that harmonic and difference frequency coherent superposition of these two methods,at both organizational efficiency injury with good results,are worthy of further study.Take in account,it was very flexible to choose fundamental frequency and difference frequency in the mode of interference of difference frequency.The effect of partition areas proportion of transducer surface,difference frequency,attenuation and non-linear to dual-frequency acoustic field based on Rayleigh integral were discussed in this paper.The results show that with the proper choosing of partition area proportion and frequency difference,the injury sound focal region of dual-frequency acoustic field is larger than that of a single frequency significantly,and the distribution of sound pressure in acoustic focus region(AFR) was uniformity.The AFR change from ellipsoid to tadpole with the strengthen of attenuation and non-linear;The spatial and temporal characteristics of dual-frequency focused acoustic field of the differential frequency coherence mode were investigated too.Last,we did some experiments to detection the acoustic field and lesion in tissue in vitro for dual-frequency focused transducer.