| 摘要 |
An ultrasonic echography apparatus which comprises a first processing circuit (100) of a known type for the processing of the ultrasonic echos in order to display an A-type echogram on a display device (103), and a second processing circuit (200) which is connected parallel to the first processing circuit and which consists mainly of an amplifier (210), a group of n parallel connected channels (220a . . . 220n) each of which comprises at least one band-pass filter (221a . . . 221n) and one envelope detector (222a . . . 222n), an arithmetic circuit (240) for calculating an indicator for the spread of the amplitudes of the signals of central frequency of each channel, and an evaluation circuit (250) which determines, again for display on the device (103), the value of the ultrasonic attenuation factor in the tissues examined, the evaluation being possible because of the fact that the calculated spread indicator is directly locally correlated to the attenuation factor which is the slope of the curve of the variation of the ultrasonic attenuation as a function of the frequency in the tissues examined. |
