Aberration, clutter, and reverberation degrade the quality of ultrasonic images. When an acoustic pulse propagates through tissue these effects occur simultaneously and it is difficult to obtain independent estimates for the precise source of the point spread function broadening. The purpose of this paper is to characterize the sources of clutter and reverberation with a simulation of ultrasonic propagation through the abdomen. A full-wave equation that describes nonlinear propagation in a heterogeneous attenuating medium is solved numerically with finite differences in the time domain (FDTD). Three dimensional solutions of the equation are verified with water tank measurements of a commercial diagnostic ultrasound transducer and are shown to be in excellent agreement in terms of the fundamental and harmonic acoustic fields, and the power spectrum at the focus. The linear and nonlinear components of the algorithm are also verified independently. In the linear non-attenuating regime solutions match results from Field II, a well established software package used in transducer modeling, to within 0.3 dB. In addition to thermoviscous attenuation we present a numerical solution of the relaxation attenuation laws that allows modeling of arbitrary frequency dependent attenuation, such as that observed in tissue. A perfectly matched layer (PML) is implemented at the boundaries with a novel numerical implementation that allows the PML to be used with high order discretizations. A -78 dB reduction in the reflected amplitude is demonstrated. The numerical algorithm is used to simulate a focused ultrasonic pulse propagating through a histologically determined representation of the human abdomen. An ultrasound image is created in silicon using the same physical and algorithmic process used in an ultrasound scanner: a series of pulses are transmitted through heterogeneous scattering tissue and the received echoes are used in a delay-and-sum beamforming algorithm to generate a images. The resulting harmonic image exhibits characteristic improvement in lesion boundary definition and contrast when compared to the fundamental image. We demonstrate a mechanism of harmonic image quality improvement by showing that the harmonic point spread function is less sensitive to reverberation clutter.
{"title":"P3B-2 Clutter From Multiple Scattering and Aberration in a Nonlinear Medium","authors":"G. Pinton, J. Dahl, G. Trahey","doi":"10.1109/ULTSYM.2007.437","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.437","url":null,"abstract":"Aberration, clutter, and reverberation degrade the quality of ultrasonic images. When an acoustic pulse propagates through tissue these effects occur simultaneously and it is difficult to obtain independent estimates for the precise source of the point spread function broadening. The purpose of this paper is to characterize the sources of clutter and reverberation with a simulation of ultrasonic propagation through the abdomen. A full-wave equation that describes nonlinear propagation in a heterogeneous attenuating medium is solved numerically with finite differences in the time domain (FDTD). Three dimensional solutions of the equation are verified with water tank measurements of a commercial diagnostic ultrasound transducer and are shown to be in excellent agreement in terms of the fundamental and harmonic acoustic fields, and the power spectrum at the focus. The linear and nonlinear components of the algorithm are also verified independently. In the linear non-attenuating regime solutions match results from Field II, a well established software package used in transducer modeling, to within 0.3 dB. In addition to thermoviscous attenuation we present a numerical solution of the relaxation attenuation laws that allows modeling of arbitrary frequency dependent attenuation, such as that observed in tissue. A perfectly matched layer (PML) is implemented at the boundaries with a novel numerical implementation that allows the PML to be used with high order discretizations. A -78 dB reduction in the reflected amplitude is demonstrated. The numerical algorithm is used to simulate a focused ultrasonic pulse propagating through a histologically determined representation of the human abdomen. An ultrasound image is created in silicon using the same physical and algorithmic process used in an ultrasound scanner: a series of pulses are transmitted through heterogeneous scattering tissue and the received echoes are used in a delay-and-sum beamforming algorithm to generate a images. The resulting harmonic image exhibits characteristic improvement in lesion boundary definition and contrast when compared to the fundamental image. We demonstrate a mechanism of harmonic image quality improvement by showing that the harmonic point spread function is less sensitive to reverberation clutter.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"24 1","pages":"1736-1739"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85532922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Castañeda, M. Zhang, K. Hoyt, K. Bylund, J. Christensen, W. Saad, J. Strang, D. Rubens, K. Parker
Radiofrequency ablation (RFA) is a minimally invasive thermal therapy that is under investigation as an alternative to surgery for treating liver tumors. Currently, there is a need to monitor the process of lesion creation to guarantee complete treatment of the diseased tissue. In a previous study, sonoelastography was used to detect and measure RFA lesions during exposed liver experiments in a porcine model in vivo. Manual outlining of these lesions in the sonoelastographic images is challenging due to a lack of boundary definition and artifacts formed by respiratory motion and perfusion. As a result, measuring the lesions becomes a time-consuming process with high variability. This work introduces a semi-automatic segmentation algorithm for sonoelastographic data based on level set methods. This algorithm aims to reduce the variability and processing time involved in manual segmentation while maintaining comparable results. For this purpose, eleven RFA lesions are created in five porcine livers exposed through a midline incision. Three independent observers perform manual and semi-automatic measurements on the in vivo sonoelastographic images. These results are compared to measurements from gross pathology. In addition, we assess the feasibility of performing sonoelastograhic measurements transcutaneously. The procedure previously described is repeated with three more lesions without exposing the liver. Overall, the semi-automatic algorithm outperforms manual segmentation in accuracy, speed, and repeatability. These results suggest that sonoelastography in combination with the segmentation algorithm has the potential to be used as a complementary technique to conventional ultrasound for thermal ablation monitoring and follow-up imaging.
{"title":"P1C-4 Real-Time Semi-Automatic Segmentation of Hepatic Radiofrequency Ablated Lesions in an In Vivo Porcine Model Using Sonoelastography","authors":"B. Castañeda, M. Zhang, K. Hoyt, K. Bylund, J. Christensen, W. Saad, J. Strang, D. Rubens, K. Parker","doi":"10.1109/ULTSYM.2007.337","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.337","url":null,"abstract":"Radiofrequency ablation (RFA) is a minimally invasive thermal therapy that is under investigation as an alternative to surgery for treating liver tumors. Currently, there is a need to monitor the process of lesion creation to guarantee complete treatment of the diseased tissue. In a previous study, sonoelastography was used to detect and measure RFA lesions during exposed liver experiments in a porcine model in vivo. Manual outlining of these lesions in the sonoelastographic images is challenging due to a lack of boundary definition and artifacts formed by respiratory motion and perfusion. As a result, measuring the lesions becomes a time-consuming process with high variability. This work introduces a semi-automatic segmentation algorithm for sonoelastographic data based on level set methods. This algorithm aims to reduce the variability and processing time involved in manual segmentation while maintaining comparable results. For this purpose, eleven RFA lesions are created in five porcine livers exposed through a midline incision. Three independent observers perform manual and semi-automatic measurements on the in vivo sonoelastographic images. These results are compared to measurements from gross pathology. In addition, we assess the feasibility of performing sonoelastograhic measurements transcutaneously. The procedure previously described is repeated with three more lesions without exposing the liver. Overall, the semi-automatic algorithm outperforms manual segmentation in accuracy, speed, and repeatability. These results suggest that sonoelastography in combination with the segmentation algorithm has the potential to be used as a complementary technique to conventional ultrasound for thermal ablation monitoring and follow-up imaging.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"18 1","pages":"1341-1344"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81650151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Size and cost considerations often require engineers and RF module designers to explore various possible implementations. While some of the alternatives have clear advantages in terms of size and performance they could be expensive. Often there are alternatives which could be very attractive (cost and size wise) provided the required performance can be achieved. Having a flexible design tool/framework which can help in this exploration process is essential to answer some of these difficult questions with some level of confidence during early stages of design. We explored the possibility of designing a wire bonded single ended 881.5 MHz inter-stage SAW (surface acoustic wave) RF filter for use in the WCDMA (wideband code division multiple access) path of a dual mode (GSM/WCDMA) receiver section. This filter not only had to meet the requirements of low insertion loss and high rejection in the Tx band (824 MHz to 849 MHz) but also had to meet a -40 dB broadband rejection up to 6 GHz. Meeting these stringent broadband requirements using wire bonds is not easy. (High frequency resonances created by transducer capacitance and the increased ground inductance due to wire bonds degrades broadband rejection.) We first describe some of the basic elements of our flexible design framework (which has been implemented as a design kit in Agilent's ADS, advanced design system). Secondly, we show some of the SAW structures (Pure DMS, Hybrids (DMS + Ladder Elements)) that we explored to meet this filter requirement using our design framework. The modeling and analysis of wire bond effects using lumped element models and wire bond models (in ADS) in conjunction with the Full die EM (Electromagnetic) simulation (using ADS Momentum) was key to understanding the dominant parasitic effects. We summarize some of our observations based on this analysis. This helped us arrive at an interesting implementation of a 4-track DMS SAW Filter structure to achieve -45 dB rejection up to 7 GHz (~5 dB margin w.r.t spec) and low loss of -2.5 dB over -30 C to +85 C temperature range. We show simulation and measurement results of this filter fabricated on 42-LiTaO3 substrate.
{"title":"10E-4 Modeling and Design of a Wire Bonded Low Loss Single Ended DMS Filter Having Broadband Rejection of -45 dB","authors":"J. Rao, A. Loseu, K. Gamble","doi":"10.1109/ULTSYM.2007.240","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.240","url":null,"abstract":"Size and cost considerations often require engineers and RF module designers to explore various possible implementations. While some of the alternatives have clear advantages in terms of size and performance they could be expensive. Often there are alternatives which could be very attractive (cost and size wise) provided the required performance can be achieved. Having a flexible design tool/framework which can help in this exploration process is essential to answer some of these difficult questions with some level of confidence during early stages of design. We explored the possibility of designing a wire bonded single ended 881.5 MHz inter-stage SAW (surface acoustic wave) RF filter for use in the WCDMA (wideband code division multiple access) path of a dual mode (GSM/WCDMA) receiver section. This filter not only had to meet the requirements of low insertion loss and high rejection in the Tx band (824 MHz to 849 MHz) but also had to meet a -40 dB broadband rejection up to 6 GHz. Meeting these stringent broadband requirements using wire bonds is not easy. (High frequency resonances created by transducer capacitance and the increased ground inductance due to wire bonds degrades broadband rejection.) We first describe some of the basic elements of our flexible design framework (which has been implemented as a design kit in Agilent's ADS, advanced design system). Secondly, we show some of the SAW structures (Pure DMS, Hybrids (DMS + Ladder Elements)) that we explored to meet this filter requirement using our design framework. The modeling and analysis of wire bond effects using lumped element models and wire bond models (in ADS) in conjunction with the Full die EM (Electromagnetic) simulation (using ADS Momentum) was key to understanding the dominant parasitic effects. We summarize some of our observations based on this analysis. This helped us arrive at an interesting implementation of a 4-track DMS SAW Filter structure to achieve -45 dB rejection up to 7 GHz (~5 dB margin w.r.t spec) and low loss of -2.5 dB over -30 C to +85 C temperature range. We show simulation and measurement results of this filter fabricated on 42-LiTaO3 substrate.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"4 1","pages":"941-944"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81960319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work addresses several aspects of damage detection and evaluation in composite laminates, in the general context of structural health monitoring. A group delay measurement technique is proposed using modally-selective Lamb-wave transducers for the detection and sizing of delaminations in woven quasi-isotropic and carbon-epoxy cross- ply composites. Unlike amplitude or energy based Lamb-wave methods, this method is insensitive to transducer coupling. The first asymmetric Lamb mode was used in the investigation because of its extended low-dispersion zone and its relatively short wavelength, at any given frequency. The transducers used to excite and detect the Lamb waves are array-type transducers able to select a specific mode. First, inserts of different sizes and different types introduced in the mid-plane during fabrication in a carbon-epoxy plain-weave quasi-isotropic composite panel were investigated. A simple "ray" analysis taking into account the observed change in group velocity and the measured time delay induced geometrically by the defect accounts accurately for the size of the defects. The same technique was applied to the detection of impact damage in cross-ply carbon-epoxy laminates. The naturally produced defects are more complex as an impact produces delaminations distributed at multiple lamina interfaces throughout the thickness of the panel, as well as matrix damage and fiber cracking. The cumulative effect of the complex damage upon the propagating wave is, again, to lower its group velocity. The time-delay measured vs. the accumulation of impact damage is significant and it correlates with the damage extent. The results are repeatable and consistent, suggesting time-delay as a reliable damage parameter for quantitative monitoring of delaminations and impact damage in composites.
{"title":"7D-5 Detection and Sizing of Delaminations in Composites Using Modally-Selective Lamb-Wave Transducers","authors":"G. Petculescu, S. Krishnaswamy, J. Achenbach","doi":"10.1109/ULTSYM.2007.155","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.155","url":null,"abstract":"This work addresses several aspects of damage detection and evaluation in composite laminates, in the general context of structural health monitoring. A group delay measurement technique is proposed using modally-selective Lamb-wave transducers for the detection and sizing of delaminations in woven quasi-isotropic and carbon-epoxy cross- ply composites. Unlike amplitude or energy based Lamb-wave methods, this method is insensitive to transducer coupling. The first asymmetric Lamb mode was used in the investigation because of its extended low-dispersion zone and its relatively short wavelength, at any given frequency. The transducers used to excite and detect the Lamb waves are array-type transducers able to select a specific mode. First, inserts of different sizes and different types introduced in the mid-plane during fabrication in a carbon-epoxy plain-weave quasi-isotropic composite panel were investigated. A simple \"ray\" analysis taking into account the observed change in group velocity and the measured time delay induced geometrically by the defect accounts accurately for the size of the defects. The same technique was applied to the detection of impact damage in cross-ply carbon-epoxy laminates. The naturally produced defects are more complex as an impact produces delaminations distributed at multiple lamina interfaces throughout the thickness of the panel, as well as matrix damage and fiber cracking. The cumulative effect of the complex damage upon the propagating wave is, again, to lower its group velocity. The time-delay measured vs. the accumulation of impact damage is significant and it correlates with the damage extent. The results are repeatable and consistent, suggesting time-delay as a reliable damage parameter for quantitative monitoring of delaminations and impact damage in composites.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"9 1","pages":"597-599"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82018941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper reconsiders the implementation details of plate wave diffraction tomography for quantitative nondestructive evaluation of flat isotropic plates. Compared to previous implementations, the approach presented here requires substantially fewer individual wave field measurements, while being also more flexible with respect to the source-receiver configuration geometry. This is achieved 1) by assuming the damage location is known, since this can be efficiently determined using other guided wave techniques and 2) by considering only far-field scatter measurements, which are usually possible if the damage location is already known prior to the imaging. Using numerical simulations of plate wave scattering due to cylindrical damage obstacles of varying size and severity, both the quantitative performance and measurement efficiency of the new implementation strategy are demonstrated.
{"title":"P4G-3 An Efficient Measurement Strategy for Plate Wave Diffraction Tomography","authors":"A. Rohde, M. Veidt","doi":"10.1109/ULTSYM.2007.516","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.516","url":null,"abstract":"This paper reconsiders the implementation details of plate wave diffraction tomography for quantitative nondestructive evaluation of flat isotropic plates. Compared to previous implementations, the approach presented here requires substantially fewer individual wave field measurements, while being also more flexible with respect to the source-receiver configuration geometry. This is achieved 1) by assuming the damage location is known, since this can be efficiently determined using other guided wave techniques and 2) by considering only far-field scatter measurements, which are usually possible if the damage location is already known prior to the imaging. Using numerical simulations of plate wave scattering due to cylindrical damage obstacles of varying size and severity, both the quantitative performance and measurement efficiency of the new implementation strategy are demonstrated.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"1 1","pages":"2054-2057"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79777141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Although side looking intravascular ultrasound (SL-IVUS) imaging systems using single element piezoelectric transducers set the resolution standard in the assessment of the extent of coronary artery disease, improvements in transducer performance are needed to perform harmonic imaging and high resolution imaging of vulnerable plaque. With their small channel count, annular arrays exploiting the inherent broad bandwidth of CMUTs and electronic focusing capability of integrated electronics provide a path for desired SL-IVUS imaging catheters. In this paper, we first describe the design, low temperature fabrication of an 840 mum diameter, 8 element CMUT annular array. Testing of the individual elements in oil shows a uniform device behavior with 100% fractional bandwidth around 20 MHz without including the effects of attenuation and diffraction. We also present linear scan imaging results obtained on wire targets in oil, tissue and tissue mimicking phantoms using both unfocused and dynamically focused transducers. The results for axial and lateral resolution are in agreement predicted by the simulations and show the feasibility of this approach for high resolution SL-IVUS imaging.
{"title":"2F-2 Annular CMUT Arrays for Side Looking Intravascular Ultrasound Imaging","authors":"S. Carlier, A. Şişman, M. Karaman","doi":"10.1109/ULTSYM.2007.34","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.34","url":null,"abstract":"Although side looking intravascular ultrasound (SL-IVUS) imaging systems using single element piezoelectric transducers set the resolution standard in the assessment of the extent of coronary artery disease, improvements in transducer performance are needed to perform harmonic imaging and high resolution imaging of vulnerable plaque. With their small channel count, annular arrays exploiting the inherent broad bandwidth of CMUTs and electronic focusing capability of integrated electronics provide a path for desired SL-IVUS imaging catheters. In this paper, we first describe the design, low temperature fabrication of an 840 mum diameter, 8 element CMUT annular array. Testing of the individual elements in oil shows a uniform device behavior with 100% fractional bandwidth around 20 MHz without including the effects of attenuation and diffraction. We also present linear scan imaging results obtained on wire targets in oil, tissue and tissue mimicking phantoms using both unfocused and dynamically focused transducers. The results for axial and lateral resolution are in agreement predicted by the simulations and show the feasibility of this approach for high resolution SL-IVUS imaging.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"55 1","pages":"84-87"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84391243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Goland, L. Kushkuley, S. Mimran, Y. Zadok, S. Ben-Ezra, A. Shalgi, A. Rybianets
The model developed by the authors for strongly focused HIFU [2] was verified experimentally. The verification was performed for 1.03 MHz focusing transducer loaded by the water. The transducer comprised spherical piezo-element immersed in the mineral oil and had aperture diameter 84 mm. and focal radius 54 mm. At the first step, acoustic field distribution in a plane, which was close and parallel to the focal plane, was measured at 10 W of input electric power. Using this data, the normal velocity distribution over the plane which is tangent to the centre point of the spherical radiator was reconstructed. This distribution was further scaled and served as boundary conditions for calculation of high intensity field distribution using approach described in [2]. At the second step the model predictions were compared with the data extracted from the acoustical pressure waveforms measured for different values of the output acoustic power. In addition to usually extracted pressure harmonic content, the spatial distributions of harmonics of on-axis projection of particle velocity have been obtained from pressure harmonic distributions with the angle spectrum expansion, providing connection between pressure and particle velocity harmonics. The predictions of the pressure positive and negative peaks, harmonic content and dependence of the harmonic effective propagation angle on the harmonic number fitted closely the corresponding experimental results. The proposed approach allows accurate prediction of strongly focused HIFU fields based on the measurements of low-intensity field distributions.
{"title":"P1B-7 Experimental and Theoretical Study of Strongly Focused High Intensity Ultrasound","authors":"V. Goland, L. Kushkuley, S. Mimran, Y. Zadok, S. Ben-Ezra, A. Shalgi, A. Rybianets","doi":"10.1109/ULTSYM.2007.328","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.328","url":null,"abstract":"The model developed by the authors for strongly focused HIFU [2] was verified experimentally. The verification was performed for 1.03 MHz focusing transducer loaded by the water. The transducer comprised spherical piezo-element immersed in the mineral oil and had aperture diameter 84 mm. and focal radius 54 mm. At the first step, acoustic field distribution in a plane, which was close and parallel to the focal plane, was measured at 10 W of input electric power. Using this data, the normal velocity distribution over the plane which is tangent to the centre point of the spherical radiator was reconstructed. This distribution was further scaled and served as boundary conditions for calculation of high intensity field distribution using approach described in [2]. At the second step the model predictions were compared with the data extracted from the acoustical pressure waveforms measured for different values of the output acoustic power. In addition to usually extracted pressure harmonic content, the spatial distributions of harmonics of on-axis projection of particle velocity have been obtained from pressure harmonic distributions with the angle spectrum expansion, providing connection between pressure and particle velocity harmonics. The predictions of the pressure positive and negative peaks, harmonic content and dependence of the harmonic effective propagation angle on the harmonic number fitted closely the corresponding experimental results. The proposed approach allows accurate prediction of strongly focused HIFU fields based on the measurements of low-intensity field distributions.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"6 1","pages":"1305-1308"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84501017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper describes an SH-SAW based sensor device which can be directly dipped into a liquid. The sensor device is composed of a two-channel SH-SAW delay line on a 36Y-X LiTaO3. Those IDTs are surrounded with epoxy walls with a 50 mum height and a 160 mum thickness. Since the epoxy walls are constructed by a photo-lithography technique using a thick epoxy based photo resist, the thickness of wall can be minimized and as a result the SH-SAW propagation loss due to the walls can be minimized. Glass covers with an epoxy adhesive are attached onto the walls. Then air-cavities above the IDTs can be achieved and the IDTs can be perfectly isolated from the liquid. In this paper, experimental results of 50 MHz dip-type SH-SAW sensors on 36Y-X LiTaO3 are presented. Since the SH-SAW which propagates on the un-metallized propagation area in a liquid with a low permittivity attenuates due to surface skimming bulk wave excitation, the obtained permittivity and conductivity are slightly different from the exact values. In order to improve this drawback, a compensation method is presented.
{"title":"P4J-3 Dip-Type Liquid-Phase Sensor Using SH-SAW","authors":"T. Kogai, H. Yatsuda, S. Shiokawa","doi":"10.1109/ULTSYM.2007.526","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.526","url":null,"abstract":"This paper describes an SH-SAW based sensor device which can be directly dipped into a liquid. The sensor device is composed of a two-channel SH-SAW delay line on a 36Y-X LiTaO3. Those IDTs are surrounded with epoxy walls with a 50 mum height and a 160 mum thickness. Since the epoxy walls are constructed by a photo-lithography technique using a thick epoxy based photo resist, the thickness of wall can be minimized and as a result the SH-SAW propagation loss due to the walls can be minimized. Glass covers with an epoxy adhesive are attached onto the walls. Then air-cavities above the IDTs can be achieved and the IDTs can be perfectly isolated from the liquid. In this paper, experimental results of 50 MHz dip-type SH-SAW sensors on 36Y-X LiTaO3 are presented. Since the SH-SAW which propagates on the un-metallized propagation area in a liquid with a low permittivity attenuates due to surface skimming bulk wave excitation, the obtained permittivity and conductivity are slightly different from the exact values. In order to improve this drawback, a compensation method is presented.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"42 1","pages":"2091-2094"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84630509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The temperature stability of surface acoustic wave (SAW) resonators on ST-like quartz cuts can be increased by using double resonators. For this the turnover temperatures of the two single resonators are chosen above and below the reference (i.e. room) temperature, respectively. In the past, coils were necessary for improving temperature stability. In the present paper, solutions of temperature stable one-port double resonators without coils are described. The improvement of temperature stability is discussed in connection with the resonance type (resonance or antiresonance), the connection type of the single resonators, the use of capacitances and inductances and with the considered resonance (or antiresonance) component occurred by splitting due to resonator coupling. The parallel connection of two single resonators with different propagation directions is treated in more detail. It is shown that the temperature coefficient of frequency of 1st order (TCF1) as well as that of 2nd order (TCF2) can be compensated by such a circuit. For this a capacitance connected in parallel to the double resonator is not required to compensate the TCF2 but it proved to be suitable for correcting the TCF1. Finally a double one-port resonator structure on 35.5degrotY quartz is investigated experimentally.
{"title":"10E-0 Improved Temperature Stability of One-Port SAW Resonators Achieved without Coils","authors":"G. Martin, H. Schmidt, B. Wall","doi":"10.1109/ULTSYM.2007.236","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.236","url":null,"abstract":"The temperature stability of surface acoustic wave (SAW) resonators on ST-like quartz cuts can be increased by using double resonators. For this the turnover temperatures of the two single resonators are chosen above and below the reference (i.e. room) temperature, respectively. In the past, coils were necessary for improving temperature stability. In the present paper, solutions of temperature stable one-port double resonators without coils are described. The improvement of temperature stability is discussed in connection with the resonance type (resonance or antiresonance), the connection type of the single resonators, the use of capacitances and inductances and with the considered resonance (or antiresonance) component occurred by splitting due to resonator coupling. The parallel connection of two single resonators with different propagation directions is treated in more detail. It is shown that the temperature coefficient of frequency of 1st order (TCF1) as well as that of 2nd order (TCF2) can be compensated by such a circuit. For this a capacitance connected in parallel to the double resonator is not required to compensate the TCF2 but it proved to be suitable for correcting the TCF1. Finally a double one-port resonator structure on 35.5degrotY quartz is investigated experimentally.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"14 1","pages":"925-928"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85343659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Deffieux, J. Gennisson, G. Montaldo, M. Tanter, M. Fink
The non invasive and in vivo assessment of the active and passive properties of the musculoskeletal system remains today a great challenge for the understanding of muscular diseases. In a previous paper, we showed that the transient contraction of a muscle fiber bundle triggered by electrostimulation can be followed in space and time by an ultrafast ultrasound system. On the one hand, this experiment is generalized to measure the three dimensional (3D) velocity fields allowing a much easier localization of the contracting fibers bundle. On the other hand, the supersonic shear imaging technique is applied to assess viscoelastic properties of the biceps brachii in different conditions. By combining in vivo imaging of both passive and active muscle activity, this study aims to provide new potential ultrasonic tools for muscle diseases diagnosis and monitoring. In order to image the contraction, which is a very quick phenomenon, an ultrasound scanner able to take up to 5000 frames/s was used. Tissue velocities were obtained from conventional speckle tracking techniques. The probe, positioned perpendicularly to the arm in a water tank, was moved with a linear motor. For each position, the imaging system was set to trigger an electrostimulation firing the contraction. A second experiment for the assessment of passive muscle elastic properties in different positions of the arm and contraction levels is then performed using the same probe in the supersonic shear imaging (SSI) mode. Generated by the radiation force induced by a focused ultrasound beam, shear waves propagate in the medium and are imaged by an ultrafast ultrasound scanner allowing the reconstruction of viscoelastic properties. The localization of the contracting fibers bundle and the resolution of its main temporal and spatial behavior are demonstrated. Paving the way to a clinical protocol on muscle diseases, viscoelastic parameters are measured in different conditions and reproducibility is discussed. These two complementary ultrasound techniques offer new perspectives for muscle diagnosis both as an active contractile tissue and as a passive tissue.
{"title":"8C-4 Active and Passive Muscle Properties Assessed by Ultrasound Techniques","authors":"T. Deffieux, J. Gennisson, G. Montaldo, M. Tanter, M. Fink","doi":"10.1109/ULTSYM.2007.173","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.173","url":null,"abstract":"The non invasive and in vivo assessment of the active and passive properties of the musculoskeletal system remains today a great challenge for the understanding of muscular diseases. In a previous paper, we showed that the transient contraction of a muscle fiber bundle triggered by electrostimulation can be followed in space and time by an ultrafast ultrasound system. On the one hand, this experiment is generalized to measure the three dimensional (3D) velocity fields allowing a much easier localization of the contracting fibers bundle. On the other hand, the supersonic shear imaging technique is applied to assess viscoelastic properties of the biceps brachii in different conditions. By combining in vivo imaging of both passive and active muscle activity, this study aims to provide new potential ultrasonic tools for muscle diseases diagnosis and monitoring. In order to image the contraction, which is a very quick phenomenon, an ultrasound scanner able to take up to 5000 frames/s was used. Tissue velocities were obtained from conventional speckle tracking techniques. The probe, positioned perpendicularly to the arm in a water tank, was moved with a linear motor. For each position, the imaging system was set to trigger an electrostimulation firing the contraction. A second experiment for the assessment of passive muscle elastic properties in different positions of the arm and contraction levels is then performed using the same probe in the supersonic shear imaging (SSI) mode. Generated by the radiation force induced by a focused ultrasound beam, shear waves propagate in the medium and are imaged by an ultrafast ultrasound scanner allowing the reconstruction of viscoelastic properties. The localization of the contracting fibers bundle and the resolution of its main temporal and spatial behavior are demonstrated. Paving the way to a clinical protocol on muscle diseases, viscoelastic parameters are measured in different conditions and reproducibility is discussed. These two complementary ultrasound techniques offer new perspectives for muscle diagnosis both as an active contractile tissue and as a passive tissue.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"19 1","pages":"668-671"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81755091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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