OS02F026 A Flaw Reconstruction Method in Heterogeneous Media with Image-based FIT and Time Reversal Approach

The presence of the clutter of volume scattering and the echo return from rough interface hinders the detection of target in heterogeneous media. This work investigates the application of an iterative time reversal mirror to mitigate the difficulties. Numerical simulations based on pseudospectral finite-difference time-domain method are performed in one and two layered media. A wideband probe pulse is launched to initiate the process, and the time-reversed echo received at the same position is retransmitted as the renewed input signal for next iteration, and repeat the procedures iteratively. The results illustrate as the number of iteration increases, small volume clutter is eliminated, interface reverberation is suppressed relatively, and the echoes will converge to a time-harmonic waveform that corresponds to an object's dominant resonance mode. The detection of target is achieved by extracting this important acoustic signature.

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Breast Acoustic Parameter Reconstruction Method Based on Capacitive Micromachined Ultrasonic Transducer Array

Micromachines ◽

10.3390/mi12080963 ◽

2021 ◽

Vol 12 (8) ◽

pp. 963

Author(s):

Yu Pei ◽

Guojun Zhang ◽

Yu Zhang ◽

Wendong Zhang

Keyword(s):

Computed Tomography ◽

Time Reversal ◽

Sound Speed ◽

Ultrasonic Transducer ◽

Reconstruction Method ◽

Propagation Theory ◽

Speed Distribution ◽

Ultrasound Computed Tomography ◽

Wide Range ◽

Capacitive Micromachined Ultrasonic Transducer

Ultrasound computed tomography (USCT) systems based on capacitive micromachined ultrasonic transducer (CMUT) arrays have a wide range of application prospects. For this paper, a high-precision image reconstruction method based on the propagation path of ultrasound in breast tissue are designed for the CMUT ring array; that is, time-reversal algorithms and FBP algorithms are respectively used to reconstruct sound speed distribution and acoustic attenuation distribution. The feasibility of this reconstruction method is verified by numerical simulation and breast model experiments. According to reconstruction results, sound speed distribution reconstruction deviation can be reduced by 53.15% through a time-reversal algorithm based on wave propagation theory. The attenuation coefficient distribution reconstruction deviation can be reduced by 61.53% through FBP based on ray propagation theory. The research results in this paper will provide key technological support for a new generation of ultrasound computed tomography systems.

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A Novel Reconstruction Method with Time Reversal Algorithm and Evaluations for Photoacoustic Tomography

2020 42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) ◽

10.1109/embc44109.2020.9176372 ◽

2020 ◽

Author(s):

Dakun Lai ◽

Liang Mao ◽

Qi Xu ◽

Jun Li

Keyword(s):

Time Reversal ◽

Photoacoustic Tomography ◽

Reconstruction Method

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Simulation-aided time-reversal analysis for defect reconstruction in anisotropic materials

Insight - Non-Destructive Testing and Condition Monitoring ◽

10.1784/insi.2019.61.11.669 ◽

2019 ◽

Vol 61 (11) ◽

pp. 669-675

Author(s):

H Mizota ◽

Y Nagashima ◽

Y Amano ◽

K Nakahata

Keyword(s):

Elastic Constants ◽

Time Reversal ◽

Electrical Discharge ◽

Laser Scanning ◽

Focal Point ◽

Ultrasonic Method ◽

Acoustic Resonance ◽

Reconstruction Method ◽

Defect Reconstruction ◽

Ultrasonic Time

A simulation-aided defect reconstruction method using an ultrasonic time-reversal approach that uses elastic constants determined by ultrasonic field data is proposed. Scattered waves from a defect are recorded using an array probe on a polystyrene wedge and the time-reversed waves are re-emitted in a finite element simulation. The target defect in these experiments is an electrical discharge machined slit in unidirectionally solidified SUS316L stainless steel. For the time-reversal analysis, two kinds of elastic constant of SUS316L derived from an electromagnetic acoustic resonance (EMAR) method and a laser scanning ultrasonic visualisation method are used. The through-wall extent of the electrical discharge machined slit can be visually estimated from the focal point of the ultrasonic wave in the numerical model using the elastic constants determined by the laser ultrasonic method. This provides a proof of principle that the method is working.

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