| 摘要 |
PROBLEM TO BE SOLVED: To precisely measure the displacement of an objective tissue which has a large displacement amount in an ultrasonic diagnostic apparatus. SOLUTION: The displacement of an objective tissue is measured by using the ultrasonic wave of a first frequency and that of a second frequency lower than the first frequency. A reference displacement D is calculated from a phase difference mutually between two second received signals 104a and 104b before and after displacement. For folding of the phase difference occurring mutually between two first received signals 102a and 102b before and after displacement, the number of folding times is obtained by an integer (m) obtained by dividing a reference displacement D byλ/2 (λis the wavelength of the ultrasonic wave of the first frequency). Next, the displacement measuring window 106 of the first received signal and a zerocross point R before displacement are shifted in a displacing direction by m*(λ/2) to obtain an dummy displacementΔd from the phase difference mutually between a point S corresponding to the point R and a zerocross point U after displacement. The displacement of an objective tissue is calculated by m*(λ/2)+Δd. COPYRIGHT: (C)2004,JPO |
