Increasing B-mode ultrasound transmit intensity improves signal to noise ratio (SNR) by increasing backscattered echo magnitude relative to thermal noise. To ensure ultrasound remains safe, acoustic output limits exist, and regulatory bodies advise observing the ALARA (As Low As Reasonably Achievable) principle. Despite this, studies show sonographers rarely adjust intensity, resulting in unnecessary acoustic exposure or sub-optimal image quality. We have developed a framework for automated transmit intensity adjustment which we demonstrate on a Verasonics Vantage ultrasound system and C5-2v transducer. The coherence of signals received by neighboring ultrasound array elements, the lag-one coherence (LOC), quantifies clutter and temporally varying noise and serves as the automation feedback parameter. In the automated sequence, receive data are quickly acquired over a region of interest (ROI) for nine intensities ranging from mechanical indices (MI) of 0.08 to 1.4. LOC asymptotically increases with acoustic intensity as the effect of thermal noise decreases until intensity increases minimally improve SNR; the intensity at 98% of the maximum LOC is used for B-mode scanning. In preliminary hepatic imaging studies, a ROI of 7 lateral lines extending 30λ axially achieves temporally stable intensity updates. The optimization time for this ROI is 0.7 seconds, enabling real-time intensity adaptation.
