A high speed data acquisition and analysis system for ultrasonic energy measurements

A high-speed microcomputer-based data acquisition and analysis system has been interface to an ultrasound sector scanner (ATL scanner model MK-500). The primary application of the system is to measure the power spectrum of the backscattered (low-level) ultrasound signal from acoustic inhomogeneous media, such as soft biological tissues. The system digitizes the ultrasound signal with a sample rate of 16 Msample/s and stores the digitized data in temporary storage (static RAMS). When the temporary storage is full, the data are transferred to an IBM-PC where the fast Fourier transform algorithm is applied to calculate the power spectrum of the ultrasound signal. Noise-reduction algorithms are applied to the signal in the time and frequency domains. A theoretical model for the backscattered process has been developed. Investigation of the model shows that the attenuation coefficient of the tissue can be used as a discriminator between normal and abnormal tissues. The average acoustic attenuation coefficient, as a function of frequency, of 25 normal liver subjects is estimated from the power spectrum of ultrasound signal. Pattern recognition algorithms are applied to differentiate between normal and abnormal liver tissues for fifteen subjects with different types of abnormalities