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Thesis defense of Maxime Polichetti
On The October 1, 2019
14h00
Amphithéâtre de la BU des Sciences Lyon 1 sur le campus de La Doua (20 avenue Gaston Berger, 69100 Villeurbanne - Arrêt de tram T1 et T4 :La Doua - Gaston Berger)
Adaptive array processing for passive ultrasound imaging of caviation
This work focuses on the spatio-temporal monitoring by ultrasonic imaging of acoustic cavitation used in some ultrasound therapy techniques, corresponding to the formation of gas bubbles that oscillate and implode.
Initially, TD-PAM (Time Domain Passive Acoustic Mapping) method was developed to map cavitation activity from acoustic signals emitted by bubbles, passively recorded by a linear ultrasonic imaging probe. However, TD-PAM suffers from too low resolution and many reconstruction artifacts. In addition, it is time-consuming because it is formalized in the time domain (TD).
To overcome these two limitations, this work proposes advanced methods of passive ultrasound imaging. It is structured around three main contributions:
- An original adaptive method has been formalised in the time domain, based on the amplitude compression of ultrasonic signals by pth root: TD-pPAM. This approach improves the resolution and contrast of cavitation maps for a computing time equivalent to the TD-PAM.
- The notion of cross-spectral density matrix has been introduced for cavitation imaging. Four Fourier domain (FD) imaging methods were therefore studied adapted and compared: FD-PAM (non-adaptive), Robust Capon FD-RCB (adaptive, by optimization), Functional Beamforming FD-FB (adaptive, by non-linear compression) and MUltiple Signal Classification FD-MUSIC (adaptive, by subspace projection).
- The performances of these FD methods were studied experimentally in vitro in water tank with a comparison by optical imaging. The proposed adaptive FD methods have demonstrated their potential to improve spatial and temporal tracking of bubbles. FD-RCB offers a superior localization to FD-PAM but suffers from a high algorithmic complexity. The performance of FD-FB is intermediate to that of FD-PAM and FD-RCB, for a calculation complexity equivalent to FD-PAM. FD-MUSIC has the potential to highlight weak acoustic sources, but does not keep their relative quantifications.
Jury :
Adrian BASARAB MCU IRIT, Toulouse Rapporteur
Sylvie MARCOS DR L2S, Gif sur Yvette Rapporteure
Emmanuelle CANET-SOULAS PU CarMeN, Lyon Examinatrice
Jérôme GATEAU CR LIB, Paris Examinateur
Jérôme MARS PU Gipsa-Lab, Grenoble Examinateur
Christian CACHARD PU CREATIS, Lyon Invité
Bruno GILLES MCU LabTAU, Lyon Invité
François VARRAY MCU CREATIS, Lyon Directeur de thèse
Barbara NICOLAS CR CREATIS, Lyon Co-directrice de thèse
Jean-Christophe BERA PU LabTAU, Lyon Co-directeur de thèse
Initially, TD-PAM (Time Domain Passive Acoustic Mapping) method was developed to map cavitation activity from acoustic signals emitted by bubbles, passively recorded by a linear ultrasonic imaging probe. However, TD-PAM suffers from too low resolution and many reconstruction artifacts. In addition, it is time-consuming because it is formalized in the time domain (TD).
To overcome these two limitations, this work proposes advanced methods of passive ultrasound imaging. It is structured around three main contributions:
- An original adaptive method has been formalised in the time domain, based on the amplitude compression of ultrasonic signals by pth root: TD-pPAM. This approach improves the resolution and contrast of cavitation maps for a computing time equivalent to the TD-PAM.
- The notion of cross-spectral density matrix has been introduced for cavitation imaging. Four Fourier domain (FD) imaging methods were therefore studied adapted and compared: FD-PAM (non-adaptive), Robust Capon FD-RCB (adaptive, by optimization), Functional Beamforming FD-FB (adaptive, by non-linear compression) and MUltiple Signal Classification FD-MUSIC (adaptive, by subspace projection).
- The performances of these FD methods were studied experimentally in vitro in water tank with a comparison by optical imaging. The proposed adaptive FD methods have demonstrated their potential to improve spatial and temporal tracking of bubbles. FD-RCB offers a superior localization to FD-PAM but suffers from a high algorithmic complexity. The performance of FD-FB is intermediate to that of FD-PAM and FD-RCB, for a calculation complexity equivalent to FD-PAM. FD-MUSIC has the potential to highlight weak acoustic sources, but does not keep their relative quantifications.
Jury :
Adrian BASARAB MCU IRIT, Toulouse Rapporteur
Sylvie MARCOS DR L2S, Gif sur Yvette Rapporteure
Emmanuelle CANET-SOULAS PU CarMeN, Lyon Examinatrice
Jérôme GATEAU CR LIB, Paris Examinateur
Jérôme MARS PU Gipsa-Lab, Grenoble Examinateur
Christian CACHARD PU CREATIS, Lyon Invité
Bruno GILLES MCU LabTAU, Lyon Invité
François VARRAY MCU CREATIS, Lyon Directeur de thèse
Barbara NICOLAS CR CREATIS, Lyon Co-directrice de thèse
Jean-Christophe BERA PU LabTAU, Lyon Co-directeur de thèse
