Nonlinear Elastic Wave Imaging With Two-Frequency Pulse Complexes
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Solution Overview
Problem
Current ultrasound image reconstruction techniques face challenges in suppressing acoustic noise and accurately estimating nonlinear scattering due to acoustic noise and wave front aberrations, particularly in complex materials where multiple scattering occurs, leading to reduced image quality and difficulty in separating nonlinearly scattered signals.
Innovation Solution
The method involves transmitting at least two elastic wave pulse complexes with varying low-frequency (LF) and high-frequency (HF) bands, where the LF pulse manipulates material elasticity along the HF pulse path, allowing for nonlinear manipulation of propagation velocity and scattering, and using signal processing techniques to correct for pulse distortion and delay, thereby enhancing the suppression of linear scattering and pulse reverberation noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current ultrasound image reconstruction techniques are used, then image reconstruction can be performed, but acoustic noise and multiple scattering reduce image quality and make it difficult to separate nonlinearly scattered signals
Solution Approach 1:
The patent segments the scattered signal into linear scattering components and nonlinear scattering components based on their different propagation characteristics. By transmitting multiple pulse complexes with different low-frequency manipulations and processing the high-frequency received signals separately, the method isolates nonlinear scattering signals from acoustic noise and multiple scattering interference, thereby improving image quality and measurement precision.
2Measurement precision
If multiple scattering occurs in complex materials, then wave propagation is affected, but separating nonlinearly scattered signals becomes difficult
Solution Approach 1:
The patent introduces low-frequency pulses as an intermediary to manipulate material elasticity before high-frequency pulses propagate through the material. This intermediary action creates distinct propagation velocity modifications for different scattering orders, enabling the separation of nonlinearly scattered signals from multiple scattering effects through subsequent signal processing of the high-frequency components.
3Measurement precision
If wave front aberrations are present, then propagation velocity varies spatially, but accurate estimation of nonlinear scattering is reduced
Solution Approach 1:
The patent applies preliminary action by using low-frequency pulses to manipulate material elasticity and establish known propagation velocity patterns before high-frequency pulses traverse the material. This pre-manipulation creates predictable velocity variations that can be accounted for in signal processing, enabling accurate estimation of nonlinear scattering despite spatial variations in propagation velocity caused by wave front aberrations.
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
This approach improves image quality by effectively suppressing acoustic noise and enhancing the estimation of nonlinear scattering, allowing for better resolution and accurate imaging of complex materials through improved suppression of pulse reverberation noise and correction of nonlinear propagation delays.
Implementation Method 1
Nonlinear elasticity means that the material elastic stiffness changes with elastic deformation of the material. For example does the material volume compression stiffness increase with volume compression of the material with a subsequent increase in the volume compression wave propagation velocity.
Implementation Method 2
As different materials have different nonlinear elasticity, compression/expansion/deformation of a spatially heterogeneous material will change the spatial variation of the elasticity and hence produce a scattering that depends on the material strain.
Implementation Method 3
The received HF signal can contain harmonic components of the HF band produced by propagation and scattering deformation of the HF pulse
Data Source
AI summary
Elastic wave pulse complexes are transmitted towards said region where said pulse complexes are composed of a high frequency (HF) and a low frequency (LF) pulse with the same or overlapping beam directions and where the HF pulse is so close to the LF pulse that it observes the modification of the object by the LF pulse at least for a part of the image depth. Received HF signals are picked up by transducers from scattered and/or transmitted components of the transmitted HF pulses. The received HF signals are processed to form measurement or image signals for display, and combined in slow time to form noise suppressed HF signals or nonlinear scattering HF signals.