System and method for determining local attenuation for ultrasonic imaging

Abstract

Power values of backscattered ultrasonic echoes from an interrogation region of a patient's body are stored in a 2-D envelope table. The region is thereby represented as a 2-D pattern of image elements. In a processing mode, these elements are grouped into processing windows. After row averaging of the power values for each window, a window attenuation coefficient is generated corresponding to a decay parameter of a non-linear decay model of local attenuation of the interrogation region as a non-linear function of the average positional power values for each row in the processing window. The coefficients are then used to scale the power values before scan conversion and display, and thus to compensate for local attenuation. The invention can also test for tissue heterogeneity by first defining convergence and non-convergence criteria. A rationalized gain control processor then iteratively estimates the window attenuation coefficients until either criterion is met. The RGC processor then indicates heterogeneity of tissue in the corresponding processing window of the interrogation when the non-convergence criterion is met.