Piezoelectric micromachined ultrasonic transducers (PMUTs) with multiple electrodes can be utilized as multi-frequency transducers by exciting selected vibration modes of the diaphragm providing configurability that may be beneficial in modern ultrasound imaging and therapeutic techniques. This requires judicious arrangement of the electrode configuration to excite the desired modes or combination of modes. Optimization of the electrode pattern can be done using full electroacoustic Finite Element Method (FEM) simulations, but this is computationally intensive and gives limited insight into the underlying physics. This paper presents a simple and efficient approach based on the in-vacuum strain mode shapes of the PMUT diaphragm to optimize the electrode configurations for an arbitrary PMUT cell resonating at any flexural mode. Strain mode shapes are obtained both from an analytical model as well as FEM. The proposed method is compared to and verified by full electroacoustic FEM simulations of PMUTs radiating into water. The optimal electrode patterns for the first few flexural modes are found for rectangular PMUTs with three different length-to-width aspect ratios, and examples of configurable PMUTs are given by combining the optimal electrodes at two different modes.
{"title":"Electrode Design Based on Strain Mode Shapes for Configurable PMUTs","authors":"Amirfereydoon Mansoori;Lars Hoff;Hamed Salmani;Einar Halvorsen","doi":"10.1109/OJUFFC.2023.3289169","DOIUrl":"https://doi.org/10.1109/OJUFFC.2023.3289169","url":null,"abstract":"Piezoelectric micromachined ultrasonic transducers (PMUTs) with multiple electrodes can be utilized as multi-frequency transducers by exciting selected vibration modes of the diaphragm providing configurability that may be beneficial in modern ultrasound imaging and therapeutic techniques. This requires judicious arrangement of the electrode configuration to excite the desired modes or combination of modes. Optimization of the electrode pattern can be done using full electroacoustic Finite Element Method (FEM) simulations, but this is computationally intensive and gives limited insight into the underlying physics. This paper presents a simple and efficient approach based on the in-vacuum strain mode shapes of the PMUT diaphragm to optimize the electrode configurations for an arbitrary PMUT cell resonating at any flexural mode. Strain mode shapes are obtained both from an analytical model as well as FEM. The proposed method is compared to and verified by full electroacoustic FEM simulations of PMUTs radiating into water. The optimal electrode patterns for the first few flexural modes are found for rectangular PMUTs with three different length-to-width aspect ratios, and examples of configurable PMUTs are given by combining the optimal electrodes at two different modes.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"3 ","pages":"88-100"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/9292640/10031625/10160009.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49930450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1109/OJUFFC.2023.3289783
Bikash K. Sinha;Qingtao Sun
Formation anisotropic constants play an important role in the determination of formation stresses, fractures, lithology, and mechanical properties. These formation characteristics provide critical inputs to wellbore stability during drilling and optimal completion designs of hydrocarbon bearing reservoirs. However, there are no available techniques for the estimation of a sub-set of formation anisotropic constants using Logging-While-Drilling (LWD) sonic data. Inversion of LWD-sonic data for anisotropic constants is rather challenging because of a strong coupling between the collar-flexural and formation-flexural modes propagating along the borehole. The influence of a strong coupling between the collar and formation flexural modes on LWD-sonic data are significantly different in fast and slow formations. Consequently, frequency dependent sensitivities of the measured collar and formation flexural dispersions to changes in the formation anisotropic constants are significantly different as well. New inversion algorithms provide estimates of a sub-set of Transversely-Isotropic (TI)-constants from measured collar and formation flexural dispersions in both fast and slow formations. Computational results confirm validity of the proposed algorithms using synthetic dispersion data obtained in a fast Bakken shale and slow Austin chalk TI-formations in the presence of a drill-collar to account for the LWD sonic tool in a liquid-filled borehole.
{"title":"Formation Anisotropic Constants From Sonic Data Acquired While Drilling","authors":"Bikash K. Sinha;Qingtao Sun","doi":"10.1109/OJUFFC.2023.3289783","DOIUrl":"https://doi.org/10.1109/OJUFFC.2023.3289783","url":null,"abstract":"Formation anisotropic constants play an important role in the determination of formation stresses, fractures, lithology, and mechanical properties. These formation characteristics provide critical inputs to wellbore stability during drilling and optimal completion designs of hydrocarbon bearing reservoirs. However, there are no available techniques for the estimation of a sub-set of formation anisotropic constants using Logging-While-Drilling (LWD) sonic data. Inversion of LWD-sonic data for anisotropic constants is rather challenging because of a strong coupling between the collar-flexural and formation-flexural modes propagating along the borehole. The influence of a strong coupling between the collar and formation flexural modes on LWD-sonic data are significantly different in fast and slow formations. Consequently, frequency dependent sensitivities of the measured collar and formation flexural dispersions to changes in the formation anisotropic constants are significantly different as well. New inversion algorithms provide estimates of a sub-set of Transversely-Isotropic (TI)-constants from measured collar and formation flexural dispersions in both fast and slow formations. Computational results confirm validity of the proposed algorithms using synthetic dispersion data obtained in a fast Bakken shale and slow Austin chalk TI-formations in the presence of a drill-collar to account for the LWD sonic tool in a liquid-filled borehole.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"3 ","pages":"101-112"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/9292640/10031625/10164270.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49930451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1109/OJUFFC.2023.3308553
F. G. Mitri
The mean (time-averaged) longitudinal force component (i.e. acting along the direction of wave propagation) arising from the interaction of linearly-polarized plane progressive shear elastic waves, incident upon a sphere embedded in an elastic medium, is considered. Exact partial-wave series expansions are derived based on the integration of the radial component of the time-averaged elastodynamic Poynting vector in spherical coordinates. The method is verified stemming from the law of energy conservation applied to elastic scattering. The analytical modeling is useful and provides improved physical understanding of shear-to-compressional (S $to $ P) mode conversion, as well as shear-to-shear (S $to $ S) and transverse-to-transverse (T $to $ T) mode preservation in the context of the mean elastic force. The elastic wave scattering formulation based on Debye’s shear and transverse potentials is solved first, and used subsequently to derive the mathematical expression of the mean force efficiency. Numerical computations illustrate the analysis with particular emphasis on the components related to mode preservation, coupling and conversion separately. It is shown here that the total force originates from individual interactions of scattering terms between the scattered pure shear (S $to $ S) and transverse (T $to $ T) waves, in addition to shear-to-transverse (S $rightleftarrows $ T) coupling, and a shear-to-compression (S $to $ P) mode conversion that contributes negligibly to the total mean force. The benchmark solution presented in this analysis for the time-averaged elastic force of shear plane progressive waves can be utilized to validate numerical methods (such as the FEM, BEM, FDTD or other). The results can provide a priori information for the optimization and design of experimental setups in various applications in biomedical ultrasound, elastography and elasticity imaging, shear-wave activation of implantable devices, characterization of biological tissue, seismology and other related applications in elastic wave scattering and radiation force.
考虑了入射到嵌入弹性介质中的球体上的线极化平面渐进剪切弹性波的相互作用所产生的平均(时间平均)纵向力分量(即沿波传播方向作用)。基于球坐标下时均弹性动力波印亭矢量径向分量的积分，导出了精确的分波级数展开式。从弹性散射的能量守恒定律出发，对该方法进行了验证。分析建模非常有用,并提供改善的物理理解shear-to-compressional (S P - 美元)模式转换,以及shear-to-shear(美元年代)和transverse-to-transverse (T 美元T)模式上下文中的保护意味着弹性力。首先求解基于德拜剪切势和横向势的弹性波散射公式，然后推导平均力效率的数学表达式。数值计算说明了分析的结果，并分别对模态保持、耦合和转换三个部分进行了分析。这里显示的是总力源于个人交互之间的散射条件分散纯剪(美元年代)和横向(T 美元T)波,除了shear-to-transverse rightleftarrows美元(S T)耦合,和shear-to-compression (S P - 美元)模式变换可忽视地有助于总意味着力量。本文提出的剪切面进行波时均弹性力基准解可用于验证数值方法(如FEM、边界元法、时域有限差分法等)。研究结果可为生物医学超声、弹性成像、可植入设备的剪切波激活、生物组织表征、地震学和其他相关应用中弹性波散射和辐射力的实验装置的优化和设计提供先验信息。
{"title":"Mean Radiation Force of Shear Plane Waves on a Sphere in an Elastic Medium","authors":"F. G. Mitri","doi":"10.1109/OJUFFC.2023.3308553","DOIUrl":"https://doi.org/10.1109/OJUFFC.2023.3308553","url":null,"abstract":"The mean (time-averaged) longitudinal force component (i.e. acting along the direction of wave propagation) arising from the interaction of linearly-polarized plane progressive shear elastic waves, incident upon a sphere embedded in an elastic medium, is considered. Exact partial-wave series expansions are derived based on the integration of the radial component of the time-averaged elastodynamic Poynting vector in spherical coordinates. The method is verified stemming from the law of energy conservation applied to elastic scattering. The analytical modeling is useful and provides improved physical understanding of shear-to-compressional (S <inline-formula> <tex-math notation=\"LaTeX\">$to $ </tex-math></inline-formula> P) mode conversion, as well as shear-to-shear (S <inline-formula> <tex-math notation=\"LaTeX\">$to $ </tex-math></inline-formula> S) and transverse-to-transverse (T <inline-formula> <tex-math notation=\"LaTeX\">$to $ </tex-math></inline-formula> T) mode preservation in the context of the mean elastic force. The elastic wave scattering formulation based on Debye’s shear and transverse potentials is solved first, and used subsequently to derive the mathematical expression of the mean force efficiency. Numerical computations illustrate the analysis with particular emphasis on the components related to mode preservation, coupling and conversion separately. It is shown here that the total force originates from individual interactions of scattering terms between the scattered pure shear (S <inline-formula> <tex-math notation=\"LaTeX\">$to $ </tex-math></inline-formula> S) and transverse (T <inline-formula> <tex-math notation=\"LaTeX\">$to $ </tex-math></inline-formula> T) waves, in addition to shear-to-transverse (S <inline-formula> <tex-math notation=\"LaTeX\">$rightleftarrows $ </tex-math></inline-formula> T) coupling, and a shear-to-compression (S <inline-formula> <tex-math notation=\"LaTeX\">$to $ </tex-math></inline-formula> P) mode conversion that contributes negligibly to the total mean force. The benchmark solution presented in this analysis for the time-averaged elastic force of shear plane progressive waves can be utilized to validate numerical methods (such as the FEM, BEM, FDTD or other). The results can provide a priori information for the optimization and design of experimental setups in various applications in biomedical ultrasound, elastography and elasticity imaging, shear-wave activation of implantable devices, characterization of biological tissue, seismology and other related applications in elastic wave scattering and radiation force.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"3 ","pages":"128-136"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/9292640/10031625/10233021.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49930453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The resolution of 3D Ultrasound Localization Microscopy (ULM) is determined by acquisition parameters such as frequency and transducer geometry but also by microbubble (MB) concentration, which is linked to the total acquisition time needed to sample the vascular tree at different scales. In this study, we introduce a novel 3D anatomically-realistic ULM simulation framework based on two-photon microscopy (2PM) and in-vivo MB perfusion dynamics. As a proof of concept, using metrics such as MB localization error, MB count and network filling, we quantify the effect of MB concentration and PSF volume by varying probe transmit frequency (3-15 MHz). We found that while low frequencies can achieve sub-wavelength resolution as predicted by theory, they are also associated with prolonged acquisition times to map smaller vessels, thus limiting effective resolution (i.e., the smallest vessel that can be reconstructed). A linear relationship was found between the maximal MB concentration and the inverse of the point spread function (PSF) volume. Since inverse PSF volume roughly scales cubically with frequency, the reconstruction of the equivalent of 10 minutes at 15 MHz would require hours at 3 MHz. We expect that these findings can be leveraged to achieve effective reconstruction and serve as a guide for choosing optimal MB concentrations in ULM.
{"title":"An Anatomically Realistic Simulation Framework for 3D Ultrasound Localization Microscopy","authors":"Hatim Belgharbi;Jonathan Porée;Rafat Damseh;Vincent Perrot;Léo Milecki;Patrick Delafontaine-Martel;Frédéric Lesage;Jean Provost","doi":"10.1109/OJUFFC.2023.3235766","DOIUrl":"https://doi.org/10.1109/OJUFFC.2023.3235766","url":null,"abstract":"The resolution of 3D Ultrasound Localization Microscopy (ULM) is determined by acquisition parameters such as frequency and transducer geometry but also by microbubble (MB) concentration, which is linked to the total acquisition time needed to sample the vascular tree at different scales. In this study, we introduce a novel 3D anatomically-realistic ULM simulation framework based on two-photon microscopy (2PM) and in-vivo MB perfusion dynamics. As a proof of concept, using metrics such as MB localization error, MB count and network filling, we quantify the effect of MB concentration and PSF volume by varying probe transmit frequency (3-15 MHz). We found that while low frequencies can achieve sub-wavelength resolution as predicted by theory, they are also associated with prolonged acquisition times to map smaller vessels, thus limiting effective resolution (i.e., the smallest vessel that can be reconstructed). A linear relationship was found between the maximal MB concentration and the inverse of the point spread function (PSF) volume. Since inverse PSF volume roughly scales cubically with frequency, the reconstruction of the equivalent of 10 minutes at 15 MHz would require hours at 3 MHz. We expect that these findings can be leveraged to achieve effective reconstruction and serve as a guide for choosing optimal MB concentrations in ULM.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"3 ","pages":"1-13"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/9292640/10031625/10013486.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49959011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-01DOI: 10.1109/OJUFFC.2024.3362631
{"title":"2023 Index IEEE Open Journal of Ultrasonics, Ferroelectrics, and Frequency Control Vol. 3","authors":"","doi":"10.1109/OJUFFC.2024.3362631","DOIUrl":"https://doi.org/10.1109/OJUFFC.2024.3362631","url":null,"abstract":"","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"3 ","pages":"223-229"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10423418","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139700446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-21DOI: 10.1109/OJUFFC.2022.3221708
Bernard Herrera;Pietro Simeoni;Gabriel Giribaldi;Luca Colombo;Matteo Rinaldi
The present work reports on the novel usage of Scandium-doped Aluminum Nitride (AlScN) PMUT arrays for enhanced power transfer in implantable applications. Optimization considerations were explored for the PMUT array towards high performance. The transmission metric, compared to identical arrays based on Aluminum Nitride (AlN), showed a 25dB increase. Power transfer measurements also confirmed a considerable increase as compared to previous work based on AlN. Different matching strategies were explored to maximize the output power including inductor conjugate matching and matching utilizing resonators in series and parallel topologies. A full characterization of the transferred power versus incident acoustic intensity on the array revealed transmission of power levels of several milliwatts for intensities below the Food and Drug Administration’s (FDA) limit. The performance of the array, as compared with other implementations with a range of frequencies, dimensions and input acoustic intensities was bench-marked through the use of the conversion efficiency as the figure-of-merit. The practical applicability of the system, utilizing a realistic tissue phantom as the medium, was proven by interfacing with a commercially available boost converter to obtain a rectified voltage and power levels sufficient for powering and charging intra-body electronics.
{"title":"Scandium-Doped Aluminum Nitride PMUT Arrays for Wireless Ultrasonic Powering of Implantables","authors":"Bernard Herrera;Pietro Simeoni;Gabriel Giribaldi;Luca Colombo;Matteo Rinaldi","doi":"10.1109/OJUFFC.2022.3221708","DOIUrl":"10.1109/OJUFFC.2022.3221708","url":null,"abstract":"The present work reports on the novel usage of Scandium-doped Aluminum Nitride (AlScN) PMUT arrays for enhanced power transfer in implantable applications. Optimization considerations were explored for the PMUT array towards high performance. The transmission metric, compared to identical arrays based on Aluminum Nitride (AlN), showed a 25dB increase. Power transfer measurements also confirmed a considerable increase as compared to previous work based on AlN. Different matching strategies were explored to maximize the output power including inductor conjugate matching and matching utilizing resonators in series and parallel topologies. A full characterization of the transferred power versus incident acoustic intensity on the array revealed transmission of power levels of several milliwatts for intensities below the Food and Drug Administration’s (FDA) limit. The performance of the array, as compared with other implementations with a range of frequencies, dimensions and input acoustic intensities was bench-marked through the use of the conversion efficiency as the figure-of-merit. The practical applicability of the system, utilizing a realistic tissue phantom as the medium, was proven by interfacing with a commercially available boost converter to obtain a rectified voltage and power levels sufficient for powering and charging intra-body electronics.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"2 ","pages":"250-260"},"PeriodicalIF":0.0,"publicationDate":"2022-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9956971","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62907888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Technologies to visualize whole organs across scales in vivo are essential for our understanding of biology in health and disease. To date, only post-mortem techniques achieve cellular resolution across entire organs. Here, we demonstrate in vivo volumetric ultrasound localization microscopy (ULM). We detail a universal methodological pipeline including dedicated 3D ULM, motion correction and realignment algorithms, as well as post-processing quantification of cerebral blood diameter and flow. We illustrate the power of this approach, by revealing the whole rat brain vasculature at a 14-fold improved resolution of $12 ~mu text{m}$ , and cerebral blood flows ranging from 1 to 120 mm/s. The exposed methodology and results pave the way to the investigation of in vivo vascular and hemodynamic processes across the mammalian brain in health and disease.
{"title":"Volumetric Ultrasound Localization Microscopy of the Whole Rat Brain Microvasculature","authors":"Baptiste Heiles;Arthur Chavignon;Antoine Bergel;Vincent Hingot;Hicham Serroune;David Maresca;Sophie Pezet;Mathieu Pernot;Mickael Tanter;Olivier Couture","doi":"10.1109/OJUFFC.2022.3214185","DOIUrl":"https://doi.org/10.1109/OJUFFC.2022.3214185","url":null,"abstract":"Technologies to visualize whole organs across scales in vivo are essential for our understanding of biology in health and disease. To date, only post-mortem techniques achieve cellular resolution across entire organs. Here, we demonstrate in vivo volumetric ultrasound localization microscopy (ULM). We detail a universal methodological pipeline including dedicated 3D ULM, motion correction and realignment algorithms, as well as post-processing quantification of cerebral blood diameter and flow. We illustrate the power of this approach, by revealing the whole rat brain vasculature at a 14-fold improved resolution of \u0000<inline-formula> <tex-math>$12 ~mu text{m}$ </tex-math></inline-formula>\u0000, and cerebral blood flows ranging from 1 to 120 mm/s. The exposed methodology and results pave the way to the investigation of in vivo vascular and hemodynamic processes across the mammalian brain in health and disease.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"2 ","pages":"261-282"},"PeriodicalIF":0.0,"publicationDate":"2022-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/9292640/9674185/09918020.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49907679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-10DOI: 10.1109/OJUFFC.2022.3213534
Sophie V. Heymans;Gonzalo Collado-Lara;Marta Rovituso;Hendrik J. Vos;Jan D’hooge;Nico De Jong;Koen Van Den Abeele
Superheated nanodroplets (NDs) were recently proposed for in vivo proton range verification, owing to their ability to vaporize into echogenic microbubbles (MBs) upon exposure to ionizing radiation. In a previous publication, vaporization events were detected with 2D Ultrasound Localization Microscopy (ULM) based on a pulse-echo method. Here, we introduce P-ULM, a passive version of ULM, based on the detection of acoustic signatures emitted by vaporizing NDs, without actively transmitting ultrasound. Due to the lack of a time reference for the trigger of the ND vaporization, the time differences of arrival to each transducer element are used to retrieve the position of vaporizing NDs. P-ULM, compared to ULM, can continuously detect and super-localize sparse radiation-induced vaporization events with inherent specificity against already existing microbubbles, which otherwise would hinder range verification in the presence of vascular flow. We evaluated the localization performances of both methods theoretically and experimentally, by interleaving active and passive acquisitions on ND-phantoms irradiated with protons. P-ULM offered a higher sensitivity to vaporizations, as it detected twice as many events as ULM. Both methods retrieved, in the acoustic lateral direction, the proton range and range dispersion with sub-millimeter accuracy. In the acoustic axial direction, despite a degraded theoretical resolution limit, P-ULM retrieved the proton spot size with an accuracy similar to ULM. Importantly, P-ULM detected vaporization events with high specificity in the presence of flowing MBs, which makes the technique a candidate for in vivo proton range verification in the presence of flow.
{"title":"Passive Ultrasound Localization Microscopy of Nanodroplet Vaporizations During Proton Irradiation","authors":"Sophie V. Heymans;Gonzalo Collado-Lara;Marta Rovituso;Hendrik J. Vos;Jan D’hooge;Nico De Jong;Koen Van Den Abeele","doi":"10.1109/OJUFFC.2022.3213534","DOIUrl":"10.1109/OJUFFC.2022.3213534","url":null,"abstract":"Superheated nanodroplets (NDs) were recently proposed for in vivo proton range verification, owing to their ability to vaporize into echogenic microbubbles (MBs) upon exposure to ionizing radiation. In a previous publication, vaporization events were detected with 2D Ultrasound Localization Microscopy (ULM) based on a pulse-echo method. Here, we introduce P-ULM, a passive version of ULM, based on the detection of acoustic signatures emitted by vaporizing NDs, without actively transmitting ultrasound. Due to the lack of a time reference for the trigger of the ND vaporization, the time differences of arrival to each transducer element are used to retrieve the position of vaporizing NDs. P-ULM, compared to ULM, can continuously detect and super-localize sparse radiation-induced vaporization events with inherent specificity against already existing microbubbles, which otherwise would hinder range verification in the presence of vascular flow. We evaluated the localization performances of both methods theoretically and experimentally, by interleaving active and passive acquisitions on ND-phantoms irradiated with protons. P-ULM offered a higher sensitivity to vaporizations, as it detected twice as many events as ULM. Both methods retrieved, in the acoustic lateral direction, the proton range and range dispersion with sub-millimeter accuracy. In the acoustic axial direction, despite a degraded theoretical resolution limit, P-ULM retrieved the proton spot size with an accuracy similar to ULM. Importantly, P-ULM detected vaporization events with high specificity in the presence of flowing MBs, which makes the technique a candidate for in vivo proton range verification in the presence of flow.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"2 ","pages":"203-219"},"PeriodicalIF":0.0,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9915615","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62907719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents the design, fabrication, and characterization of a 190+190 row-column addressed (RCA) capacitive micromachined ultrasonic transducer (CMUT) array integrated in a custom hand-held probe handle. The array has a designed 4.5 MHz center frequency in immersion and a pitch of $95~mu $ m which corresponds to $approx ~lambda $ /4. The array has a $2.14times2.14$ cm $^{2}$ footprint including an integrated apodization scheme to reduce ghost echoes when performing ultrasound imaging. The array was fabricated using a combination of fusion and anodic bonding, and a deposit, remove, etch, multistep (DREM) etch to reduce substrate coupling and improve electrode conductivity. The transducer array was wire-bonded to a rigid-flex printed circuit board (PCB), encapsulated in room temperature vulcanizing (RTV) silicone polymer, electromagnetic interference (EMI) shielded, and mounted in a 3D-milled PPSU probe handle. The probe was characterized using the SARUS experimental scanner and 3D volumetric imaging was demonstrated on scatter and wire phantoms. The imaging depth was derived from tissue mimicking phantom measurements (0.5 dB MHz $^{-1} text{cm}^{-1}$ attenuation) by estimating the SNR at varying depths. For a synthetic aperture imaging sequence with 96+96 emissions the imaging depth was 3.6 cm. The center frequency measured from the impulse response spectra in transmit and pulse-echo was 6.0 ± 0.9 MHz and 5.3 ± 0.4 MHz, and the corresponding relative bandwidths were 62.8 ± 4.5 % and 86.2 ± 10.4 %. The fabrication process showed clear improvement in relative receive sensitivity and transmit pressure uniformity compared to earlier silicon-on-insulator (SOI) based designs. However, at the same time it presented yield problems resulting in only around 55 % elements with a good response.
本文介绍了集成在定制手持探头手柄中的190+190行列寻址(RCA)电容式微机械超声换能器(CMUT)阵列的设计、制造和表征。该阵列的设计浸入中心频率为4.5 MHz，节距为$95~mu $ m，对应于$approx ~lambda $ /4。该阵列的占地面积为$2.14times2.14$ cm $^{2}$，包括一个集成的apodization方案，以减少执行超声成像时的鬼回波。该阵列采用融合和阳极键合的组合，以及沉积、去除、蚀刻、多步骤(DREM)蚀刻来减少衬底耦合并提高电极导电性。换能器阵列通过导线连接到刚性柔性印刷电路板(PCB)上，封装在室温硫化(RTV)有机硅聚合物中，屏蔽电磁干扰(EMI)，并安装在3d研磨的PPSU探头手柄中。使用SARUS实验扫描仪对探针进行了表征，并在散射和丝影上进行了三维体积成像。成像深度是通过估计不同深度下的信噪比，从组织模拟幻象测量(0.5 dB MHz $^{-1} text{cm}^{-1}$衰减)得出的。96+96次发射的合成孔径成像序列，成像深度为3.6 cm。发射脉冲响应谱和脉冲回波脉冲响应谱测得的中心频率分别为6.0±0.9 MHz和5.3±0.4 MHz，相应的相对带宽为62.8±4.5 % and 86.2 ± 10.4 %. The fabrication process showed clear improvement in relative receive sensitivity and transmit pressure uniformity compared to earlier silicon-on-insulator (SOI) based designs. However, at the same time it presented yield problems resulting in only around 55 % elements with a good response.
{"title":"A Hand-Held 190+190 Row–Column Addressed CMUT Probe for Volumetric Imaging","authors":"Rune Sixten Grass;Mathias Engholm;Andreas Spandet Havreland;Christopher Beers;Martin Lind Ommen;Stine Løvholt Grue Pedersen;Lars Nordahl Moesner;Matthias Bo Stuart;Mudabbir Tufail Bhatti;Borislav G. Tomov;Jørgen Arendt Jensen;Erik Vilain Thomsen","doi":"10.1109/OJUFFC.2022.3213013","DOIUrl":"10.1109/OJUFFC.2022.3213013","url":null,"abstract":"This paper presents the design, fabrication, and characterization of a 190+190 row-column addressed (RCA) capacitive micromachined ultrasonic transducer (CMUT) array integrated in a custom hand-held probe handle. The array has a designed 4.5 MHz center frequency in immersion and a pitch of \u0000<inline-formula> <tex-math>$95~mu $ </tex-math></inline-formula>\u0000 m which corresponds to \u0000<inline-formula> <tex-math>$approx ~lambda $ </tex-math></inline-formula>\u0000/4. The array has a \u0000<inline-formula> <tex-math>$2.14times2.14$ </tex-math></inline-formula>\u0000 cm\u0000<inline-formula> <tex-math>$^{2}$ </tex-math></inline-formula>\u0000 footprint including an integrated apodization scheme to reduce ghost echoes when performing ultrasound imaging. The array was fabricated using a combination of fusion and anodic bonding, and a deposit, remove, etch, multistep (DREM) etch to reduce substrate coupling and improve electrode conductivity. The transducer array was wire-bonded to a rigid-flex printed circuit board (PCB), encapsulated in room temperature vulcanizing (RTV) silicone polymer, electromagnetic interference (EMI) shielded, and mounted in a 3D-milled PPSU probe handle. The probe was characterized using the SARUS experimental scanner and 3D volumetric imaging was demonstrated on scatter and wire phantoms. The imaging depth was derived from tissue mimicking phantom measurements (0.5 dB MHz\u0000<inline-formula> <tex-math>$^{-1} text{cm}^{-1}$ </tex-math></inline-formula>\u0000 attenuation) by estimating the SNR at varying depths. For a synthetic aperture imaging sequence with 96+96 emissions the imaging depth was 3.6 cm. The center frequency measured from the impulse response spectra in transmit and pulse-echo was 6.0 ± 0.9 MHz and 5.3 ± 0.4 MHz, and the corresponding relative bandwidths were 62.8 ± 4.5 % and 86.2 ± 10.4 %. The fabrication process showed clear improvement in relative receive sensitivity and transmit pressure uniformity compared to earlier silicon-on-insulator (SOI) based designs. However, at the same time it presented yield problems resulting in only around 55 % elements with a good response.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"2 ","pages":"220-236"},"PeriodicalIF":0.0,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9913981","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62907638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-05DOI: 10.1109/OJUFFC.2022.3212342
Thomas M. Kierski;Rachel W. Walmer;James K. Tsuruta;Jianhua Yin;Emmanuel Chérin;F. Stuart Foster;Christine E. M. Demore;Isabel G. Newsome;Gianmarco F. Pinton;Paul A. Dayton
Ultrasound molecular imaging (USMI) is a technique used to noninvasively estimate the distribution of molecular markers in vivo by imaging microbubble contrast agents (MCAs) that have been modified to target receptors of interest on the vascular endothelium. USMI is especially relevant for preclinical and clinical cancer research and has been used to predict tumor malignancy and response to treatment. In the last decade, methods that improve the resolution of contrast-enhanced ultrasound by an order of magnitude and allow researchers to noninvasively image individual capillaries have emerged. However, these approaches do not translate directly to molecular imaging. In this work, we demonstrate super-resolution visualization of biomarker expression in vivo using superharmonic ultrasound imaging (SpHI) with dual-frequency transducers, targeted contrast agents, and localization microscopy processing. We validate and optimize the proposed method in vitro using concurrent optical and ultrasound microscopy and a microvessel phantom. With the same technique, we perform a proof-of-concept experiment in vivo in a rat fibrosarcoma model and create maps of biomarker expression co-registered with images of microvasculature. From these images, we measure a resolution of $23~mathrm {mu}{text {m}}$ , a nearly fivefold improvement in resolution compared to previous diffraction-limited molecular imaging studies.
{"title":"Acoustic Molecular Imaging Beyond the Diffraction Limit In Vivo","authors":"Thomas M. Kierski;Rachel W. Walmer;James K. Tsuruta;Jianhua Yin;Emmanuel Chérin;F. Stuart Foster;Christine E. M. Demore;Isabel G. Newsome;Gianmarco F. Pinton;Paul A. Dayton","doi":"10.1109/OJUFFC.2022.3212342","DOIUrl":"10.1109/OJUFFC.2022.3212342","url":null,"abstract":"Ultrasound molecular imaging (USMI) is a technique used to noninvasively estimate the distribution of molecular markers in vivo by imaging microbubble contrast agents (MCAs) that have been modified to target receptors of interest on the vascular endothelium. USMI is especially relevant for preclinical and clinical cancer research and has been used to predict tumor malignancy and response to treatment. In the last decade, methods that improve the resolution of contrast-enhanced ultrasound by an order of magnitude and allow researchers to noninvasively image individual capillaries have emerged. However, these approaches do not translate directly to molecular imaging. In this work, we demonstrate super-resolution visualization of biomarker expression in vivo using superharmonic ultrasound imaging (SpHI) with dual-frequency transducers, targeted contrast agents, and localization microscopy processing. We validate and optimize the proposed method in vitro using concurrent optical and ultrasound microscopy and a microvessel phantom. With the same technique, we perform a proof-of-concept experiment in vivo in a rat fibrosarcoma model and create maps of biomarker expression co-registered with images of microvasculature. From these images, we measure a resolution of \u0000<inline-formula> <tex-math>$23~mathrm {mu}{text {m}}$ </tex-math></inline-formula>\u0000, a nearly fivefold improvement in resolution compared to previous diffraction-limited molecular imaging studies.","PeriodicalId":73301,"journal":{"name":"IEEE open journal of ultrasonics, ferroelectrics, and frequency control","volume":"2 ","pages":"237-249"},"PeriodicalIF":0.0,"publicationDate":"2022-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9912413","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"62907424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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