ABSTRACT
The experiment was performed at the Laboratory of Ultrasonic Medicine,Department of Biomedical Engineering,Tianjin Medical University between October 2007 and July 2008.Finite difference time domain method which was proposed by Morita to simulate nonlinear ultrasound transmission was applied together with bio-heat-transfers-equation to simulate temperature distribution in the focal region.The results show that when there was a blood vessel in tissue,the blood vessel temperature rise was lower than the surrounding tissue temperature rise.The highest temperature in the surrounding tissue and the focal region above 60 ℃ were decreased with increasing vessel diameter.The blood vessel diameters lead to great changes of temperature distribution.We should consider the influence of blood vessel diameters during high intensity focused ultrasound therapy to destroy tumors