Acoustic Field Intensity Measurement in Soft Solid Tissue
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Solution Overview
Problem
Current methods fail to accurately measure and control the intensity of an acoustic field in soft solids, such as biological tissues, due to heterogeneities which can lead to beam alteration, affecting the efficacy and safety of diagnostic and therapeutic ultrasound applications.
Innovation Solution
A method that determines the local intensity of an acoustic field by calculating the ultrasound attenuation coefficient, shear modulus, and speed of sound in the target region, building a viscoelastic model, and measuring steady-state displacements to compute the intensity, allowing for efficient beam control and correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simulation based on homogenous medium is used to estimate beam power, then calculation is simple, but measurement precision deteriorates due to tissue heterogeneities
Solution Approach 1:
The patent introduces steady-state displacement measurements as an intermediary parameter to bridge the gap between simple simulation and accurate intensity measurement. By measuring the actual displacement field in the heterogeneous tissue and comparing it with simulated displacement fields, the method can infer the true acoustic intensity distribution without requiring complex direct intensity measurement systems.
Solution Approach 2:
The patent replaces direct acoustic intensity measurement with a mechanical substitution approach using displacement field measurement. Instead of attempting to directly measure the acoustic intensity which is difficult in heterogeneous media, the method measures the resulting mechanical displacement field and uses this information to infer the acoustic intensity distribution through comparison with simulations.
2Measurement precision
If inverse problem approach is used to estimate intensity distribution, then measurement precision may improve, but reliability deteriorates due to local minimum issues
Solution Approach 1:
The patent employs a feedback mechanism where the measured steady-state displacement field is continuously compared with simulated displacement fields generated from different intensity distributions. This feedback loop allows the method to iteratively refine the intensity estimation by adjusting the simulated field to match the measured displacement, thereby avoiding convergence to local minima and improving solution reliability.
Solution Approach 2:
The patent performs preliminary actions by first measuring the steady-state displacement field under the acoustic excitation, and then using this measurement as a constraint to guide the inverse problem solution. This preliminary measurement provides a reliable reference that prevents the iterative algorithm from converging to incorrect local minima, ensuring accurate intensity distribution estimation.
3Productivity
If acoustic field is applied in heterogeneous soft solid, then therapeutic effect is enhanced, but harmful factors increase due to beam alteration and overheating
Solution Approach 1:
The patent uses feedback control by continuously monitoring the steady-state displacement field and comparing it with simulated fields to detect beam alteration in real-time. When heterogeneities cause unexpected beam deflection or attenuation, the system can provide feedback to adjust the acoustic field parameters, thereby preventing harmful overheating while maintaining therapeutic efficacy.
Solution Approach 2:
The patent performs preliminary characterization of the soft solid's viscoelastic properties by measuring steady-state displacements before applying the full therapeutic acoustic field. This preliminary measurement allows the system to predict how the acoustic field will propagate through the heterogeneous tissue, enabling pre-correction of beam parameters to avoid harmful effects like overheating while ensuring effective treatment delivery.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise control and correction of acoustic field intensity, improving the efficiency and safety of ultrasound applications by accounting for tissue heterogeneities and ensuring effective diagnostic and therapeutic outcomes.
Implementation Method 1
an acoustic field emitted by an ultrasound source, for a duration such that the acoustic field induces a steady-state localized deformation of the soft solid in the target region
Implementation Method 2
building, with the values determined in steps a), b) and c), a viscoelastic model of a steady-state displacement induced by an acoustic field
Data Source
AI summary
This method, for determining the local intensity (I0) of an acoustic field propagating in a target region of a soft solid, at a position located within said target region, includes at least the following steps: determining (102) a value of an ultrasound attenuation coefficient (α) of the soft body in the target region; determining (104) a value of the shear modulus (μ) of the soft body in the target region; determining (106) a value of the speed of sound (c) in the target region of the soft body; and building (110), with the values determined in steps a), b) and c), a viscoelastic model (M) of a steady-state displacement induced by an acoustic field having a time invariant shape or a viscoelastic model of a difference between two steady-state displacements induced by an acoustic field having a time invariant shape. Moreover, this method also includes the following steps: applying (112) to the target region the acoustic field emitted by an ultrasound source, for a duration such that the acoustic field induces a steady-state localized deformation (Formula (I)) of the soft body in the target region; measuring (114) at least one steady state displacement induced by the acoustic field at a given position in the target region; and computing (116) the amplitude of the intensity of the acoustic field at said given position by inverting the viscoelastic model (M) at said given position, for the displacement(s) measured at step f).