Automated gain control for medical diagnostic ultrasound imaging

A B-mode ultrasound imaging system operates by transmitting a high-frequency sound pulse and measuring the strength and time of flight of the reflected signal. The ultrasound signal may be attenuated by as much as 60 dB in its round-trip to a target and must be normalized so that contrast is not lost in the far field. Manual controls for adjusting receiver gain versus depth are impractical in most surgical applications. This paper describes the design of a circuit to automate the time-gain function on a digital imaging system. Using a digital signal processor, the image is divided into range segments and the time-gain function is adaptively modified to normalize the statistics of each region