| 摘要 |
PROBLEM TO BE SOLVED: To determine an evaluated value of a non-linear interaction between ultrasound and an organism easily and highly accurately, in an ultrasonographic instrument in which evaluated values of the non-linear interaction is utilized. SOLUTION: A first transmission signal containing both frequencies f0 and 2f0 is transmitted, and then a second transmission signal having the polarity opposite to that of the first transmission signal is transmitted. In a reception beam processing circuit 22, a signal to which echoes of the both transmission signals are added and a signal from which the echoes are subtracted are generated. By cancelling fundamental wave components by adding, second wave harmonic components A2 remain in the added signal. Contrary to this, cancelling second higher harmonic components by subtracting, the fundamental wave components remain in the subtracted signal. Fundamental wave component AII of a frequency 2f0 is extracted from the subtracted signal, and a ratio (A2/AII) is calculated by a subtraction circuit 44. By differentiating by an HPF 46, evaluated values reflecting non-linear parameter for each depth of the living body are determined. |
