Ultrasound Coded Excitation Imaging with Retrospective Beamforming
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Solution Overview
Problem
Coded pulse excitation in ultrasonic imaging is hindered by clutter induced by pulse compression side lobes and cross-channel correlation, leading to reduced contrast resolution due to distributed scattering.
Innovation Solution
A two-step method that estimates the medium's impulse response and synthesizes virtual wavefronts for beamforming, using a multi-input, single-output system to model transmit-receive paths, allowing retrospective transmission of arbitrary waveforms without coding constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If continuous wave (CW) transmission is used, then the ultrasound system is simple to operate, but the scan time is long and motion artifacts occur
Solution Approach 1:
The patent applies periodic pulsed transmission instead of continuous wave transmission. The ultrasound system transmits coded excitation pulses at specific intervals rather than continuously, which reduces scan time and allows for motion gating between pulses. This periodic action maintains ease of operation while eliminating the time-consuming nature of CW transmission.
2Measurement precision
If high frequency ultrasound waves are used, then the resolution is improved, but the penetration depth is reduced
Solution Approach 1:
The patent changes the frequency parameter dynamically by using a chirp signal that sweeps through a range of frequencies rather than transmitting at a single high frequency. This allows the system to achieve high resolution at shallow depths while maintaining lower frequency components for deeper penetration, effectively resolving the trade-off between resolution and penetration depth.
3Measurement precision
If coded excitation is used, then the signal-to-noise ratio is improved, but the complexity of the system increases
Solution Approach 1:
The patent introduces a deconvolution filter as an intermediary processing step between signal reception and image formation. This filter acts as a mediator that simplifies the complex coded excitation signal into a form that can be processed using standard imaging techniques, thereby improving signal-to-noise ratio while managing system complexity through structured signal processing.
4Measurement precision
If long pulse duration is used, then the signal-to-noise ratio is improved, but the range resolution is degraded
Solution Approach 1:
The patent uses periodic pulsed transmission with coded excitation sequences that have specific temporal structures. By transmitting energy in periodic pulses rather than continuous waves, the system accumulates signal energy to improve signal-to-noise ratio while maintaining pulse duration characteristics that preserve range resolution through the use of deconvolution processing.
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 decouples sidelobe design from signal penetration issues, enabling flexible tradeoffs between framerate, mainlobe resolution, and contrast resolution while maintaining high sensitivity and effective pixel estimation.
Implementation Method 1
a coded excitation signal is transmitted and a reflected signal is received
Data Source
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AI summary
A method that includes transmitting coded waveforms simultaneously on multiple elements for several frames, constructing a first multi-input, single output (MISO) system from the codes to model transmit-receive paths, solving system and RF data observation by linear model theory, giving an IR set for the medium, and applying the estimates to a secondary MISO system, constructed by analogy to the first, but with pulses convenient for beamforming in the form of a focused set of single-cycle pulses for ideal focused reconstruction.