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Publication Number
US-11918420-B2
Publication Date
2024-03-05
Expiration Date
Abstract
Various approaches for focusing an ultrasound transducer having multiple transducer elements include causing the transducer elements to transmit ultrasound waves to a target region and measure reflections of the ultrasound waves off the target region; for each of at least some of the transducer elements, adjusting a parameter value associated with said each transducer element based at least in part on parameter values associated with multiple measuring transducer elements weighted by signal quality metrics associated with the reflections measured by the measuring transducer elements so as to improve an ultrasound focus at the target region.
Core Innovation
The invention relates to focusing an ultrasound transducer using reflection autofocusing for multi-element ultrasound phased arrays. An ultrasound transducer comprising a plurality of transducer elements transmits ultrasound waves to one or more target regions, and measuring transducer elements measure reflections of the ultrasound waves transmitted off the target region. The controller weights parameter values corresponding to the measuring transducer elements based at least in part on signal quality metrics associated with the measured reflections.
Based on the weighted parameter values, the controller adjusts a parameter value corresponding to each transducer element, and then causes each transducer element to transmit ultrasound waves using the adjusted parameter values. The adjusted transmission is performed so as to increase acoustic intensity at the target region. Signal quality metrics, including signal-to-noise ratio and/or repetitiveness of ultrasound parameter values across repeated measurements, determine whether measured phases, amplitudes, and/or frequencies are used directly or whether remediated parameter values are used for transducer elements receiving low-quality echoes.
The disclosed approach includes remediation of parameter values using physical modeling with an acoustic ray model and a focusing algorithm accounting for intervening-tissue aberrations, model optimization or inverse computation from sufficient-quality measurements, and/or machine learning predictors trained from sufficient-quality reflections plus intervening-tissue characteristics. Intervening-tissue characteristics may be obtained using imaging modalities such as MRI and/or CT, and the method can extend calibration across multiple discontiguous target regions to reduce per-target echo-measurement iterations.
Claims Coverage
The independent claim covers a system that focuses an ultrasound transducer by measuring reflection signals, computing signal-quality-based weights, remediating per-element parameter values, and transmitting using the adjusted parameter values to increase acoustic intensity at the target region. Across the dependent claims referenced in the partial content, the inventive features further specify how signal quality metrics are used, how weighting is formed, and how per-element parameter adjustment is obtained, including physical modeling or computationally trained predictors based on intervening tissue characteristics.
Reflection-based signal-quality weighting for transducer elements
Cause measuring transducer elements included in the plurality of transducer elements of the ultrasound transducer to measure reflections of the ultrasound waves transmitted by the plurality of transducer elements of the ultrasound transducer off the target region; weight parameter values corresponding to the measuring transducer elements at least in part by signal quality metrics associated with the reflections measured by the measuring transducer elements.
Per-element adjustment using weighted parameter values
For each transducer element of at least some of the plurality of transducer elements, adjust a parameter value corresponding to said each transducer element based at least in part on the weighted parameter values corresponding to a plurality of the measuring transducer elements.
Transmit using adjusted parameters to increase acoustic intensity
Cause said each transducer element to transmit ultrasound waves to the target region using the adjusted parameter values corresponding to said each transducer element so as to increase acoustic intensity at the target region.
Zero-weight thresholding based on signal quality metrics
Create a weighting vector with zero values for measuring transducer elements whose measured reflection signals have signal quality metrics below a predetermined threshold.
Signal-to-noise ratio as a signal quality metric
Define the signal quality metric as a signal-to-noise ratio of the measured reflections.
Distance-based weighting for parameter adjustment
Adjust parameter values for measuring transducer elements based at least in part on distances between the measuring transducer elements and each transducer element whose parameter value is adjusted.
Computationally trained predictor using intervening tissue characteristics
Adjust the parameter value for each transducer element using a computationally trained predictor that forecasts the parameter value from a characteristic of an intervening tissue between the transducer element and the target region.
Seed microbubble acoustic reflector generation
Include a seed microbubble into a target region, and have the controller generate at least one acoustic reflector from the seed microbubble and the ultrasound transducer so the reflector reflects transmitted ultrasound waves.
Overall, the claims focus on reflection autofocusing where measured reflections off the target region are assessed via signal quality metrics to form weights, those weights drive per-element adjustment of parameter values, and transmission using the adjusted parameter values increases acoustic intensity at the target region. Dependent features specify thresholding and weighting schemes, define signal-to-noise ratio as an example signal quality metric, incorporate distance-based weighting, and support parameter adjustment using a computationally trained predictor based on intervening tissue characteristics, as well as generating an acoustic reflector using a seed microbubble.
Stated Advantages
Increase acoustic intensity at the target region.
Documented Applications
Focusing an ultrasound transducer for transmitting ultrasound waves to target regions using reflection measurements off the target region.
Reflection autofocusing in multi-element ultrasound phased arrays using signal-quality-based weighting and parameter remediation.
Use of an acoustic reflector generated from a seed microbubble into a target region to reflect transmitted ultrasound waves.
Extending calibration across multiple discontiguous target regions to reduce per-target echo-measurement iterations.
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