The Research On Focal Region Of Multifocus In Hifu

Focused Ultrasound Surgery (focused ultrasound surgery, FUS) technology as a non-invasive treatment way is increasingly used in clinical treatment. Focused ultrasound technology will make the ultrasound gather at the goal target and under the thermal effects,cavitation effects,mechanical effects of ultrasound the lesions could be coagulated acutely .Spherical shell are often used to design focused ultrasound treatment head because of its high-profile and simple design features, so ultrasound technology developed rapidly. However, when this transducer widely used in clinical many problems presented. For example: high intensity focused ultrasound (HIFU) produced by shell ultrasonic transducer could not be focused through the ribs and on the treatment of large volume tumor need a long time. These problems have seriously slowed the pace of ultrasound treatment technology. The key to solve the above problems is to improve the control power of focused sound beam to produce a variety of forms of acoustic focal region. Ultrasound transducer as the core of the ultrasonic technologies in order to sove these probolems we must start from the transducers. The traditional self-focused transducer could only produce a single focus and the shape of focal region could not be changed, these faults greatly limits the application of this transducer in the ultrasonic treatment.The focused methods of ultrasounic phased array is very flexible, the phased-array could form different intensity and distribution patterns of focus depend on the shape and location of diseased tissue . Through researching on phase and amplitude control methods and analysising the sound field distribution in the direction of sound propagation of the ultrasonic phased array could achieve a good multi-focus mode , this is great significance to the develop of FUS.This paper analysis the multi-foucs sound field distribution in sound propagation direction under the previous studies of phased array multi-focus model . Through reasonable change the number of focus and arrange the position of focus ,the multi-focus of acoustic field distribution could be improved.Finally,we found set up another focus in the center of four focus model and changing its location , the characteristics of sound field distribution of this five foucs output model could be more greatly improved than two or four focus of the phased-array sound field distribution.