Relationship between the exposure dose of high intensity focused ultrasound and the heated necrosis element *

Author： Feng Ruo Zhang Qiang Li Faqi Zheng Xiaozheng Bai Jin Xu Jianyi Wang Yaojun Wang Zhibiao

ISSN： 1002-0071

Source： Progress in Natural Science, Vol.14, Iss.8, 2004-08, pp. : 710-712

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Abstract

Heated necrosis element of tissues is the basis for treating tumor by high intensity focused ultrasound (HIFU), so study on the relationship between the HIFU exposure dose and the heated necrosis element of tissues is of great significance for both HIFU clinical applications and basic research. Using Pennes and Rayleigh formulae the relationship between the exposure dose of an annular focused transducer and the heated necrosis element (i. e. biological focused region) in a bovine liver in vitro at a depth of 2 cm is simulated in an exposure dose range with radiation sound intensity of 7000~25400 W/cm 2 and exposure time of 0~20s. The theoretical results appear to be in quite good agreement with the experimental ones. It is shown that on the basis of existing theories the heated necrosis element produced by HIFU exposure can be predicted. The deviation of the theory from the experiments under higher exposure dose has also been discussed.