| 摘要 |
PURPOSE:To allow the exact calculation of a blood scattering power by removing the unnecessary components from the biotissue without affecting blood scattering components by calculating the Doppler spectra of respective moments of time and cumulatively computing the sum of the respective frequency components of the Doppler spectra excluding an unnecessary frequency range. CONSTITUTION:An ultrasonic reflection signal is inputted to an orthogonal detection circuit 1 and two kinds of orthogonal base band signals which are a real component and an imaginary component are obtd. The base band signals of a desired depth are sample-held by sample-hold circuits 2, 3 and are subjected to high-speed Fourier transform(FFT) by a Doppler spectrum calculation circuit 4 and are square summed to obtain the Doppler spectra. The reflection components from the walls and valves are removed by an unnecessary frequency range setting section 6 from the Doppler spectra obtd. in such a manner and the rest are accumulated in a Doppler spectrum accumulation section 5. The exact characterization of the biotissue is executed in this way. |
