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The Research on Focal Region of Multifocus in HIFU

Author: XiangJun
Tutor: WangZhiBiao；WangHua
School: Chongqing Medical University
Course: Biomedical Engineering
Keywords: HIFU Ultrasonic Phased Array Genetic Algorithms Multifocal
CLC: R454.3
Type: Master's thesis
Year: 2010
Downloads: 23
Quote: 0
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Abstract

Focused Ultrasound Surgery (focused ultrasound surgery, FUS) surgery as a non-invasive, non-invasive treatment is increasingly being used in clinical treatment has also been recognized by more and more patients. Focused ultrasound surgery (FUS) technology vitro ultrasonic converge on the target target ultrasound thermal effects, cavitation, mechanical effects, such as the role of the lesions occurred irreversible acute coagulation necrosis. In the course of the study, found that the self-focusing of the the spherical shell ultrasound transducer its high focus and simple design features, it is often used to design focused ultrasound therapy for head and end up with a very good therapeutic effect, and thus early focused ultrasound The technology has been rapid development. Of HIFU technology is widely used in clinical, there have been many problems to be solved. For example: shell ultrasonic transducer generates high Focused Ultrasound (HIFU) through the ribs can not focus; larger volume of tumor treatment time is too long. These issues seriously slow down the pace of the ultrasound treatment technology. The key to solving the above problems is how to improve the ability to produce a variety of forms of acoustic focal field control on the focus of the acoustic beam. The transducer is the core part of the ultrasound treatment technology to solve the above problems must start from the change can sound field algorithm. The traditional unit self-focused transducer can only produce a single focus, and the shape of the focal region can not change greatly limits its application in ultrasound treatment. The focus of the ultrasonic phased array is very flexible, and can be based on the shape and location of the lesions, and a different focus intensity and distribution pattern of the focal region. Study ultrasonic phased bursts symbol phase, the amplitude of the control method, and Analysis in the distribution characteristic of the sound field of the acoustic propagation direction (axial direction), in order to achieve good sound field multi-focus mode, and this to the technical development of the ultrasound treatment is very important significance. In this paper, based on previous studies phased array multi-focus sound field mode, the focus of the multifocal distribution of the sound field in the direction of sound propagation characteristics. Reasonable to change the focus of the number and arrangement position of the focus, in order to improve the characteristics of the acoustic field distribution of the multi-focal. The results show that: Another focus of the acoustic output mode by changing the respective focal distance formed by the five focus is set in the center of the four focus, the distribution characteristic of the sound field is greatly improved compared to the second focus and focus.

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