| Based on the analytic expressions given by T. Hasegawa, et al.. (J.Acoust. Soc. Am. 79(4) 927-931 1986) an integral for calculation of the radiation force on a plane absorbing target in spherically focused field is derived. For focused fields a general relation between acoustic power P and normal radiation force Fn, is obtained from the integral. Numerical computation of the integral is carried out for the practical HIFU source and absorbing circular target£¬ through which the value of calibration constant G can be obtained The experiments are conducted for the same source and target used in the calculation. For the given source and targets, the calculations and experiments show that there is a range of target¡¯s position where the radiation force is independent of target¡¯s position. |