A fast Rayleigh-Sommerfeld integral-based method was presented in this paper to speed up acoustic field simulation using a modified summation scheme. Partitioning source aperture with uniform large patches instead of simple sources, the modified summation scheme outperformed the conventional simple source based approach by both reducing the number of source-field interaction pairs and reusing the beam directivity of a single source patch. This modified scheme, along with Snell's law, could also facilitate wave transmission simulation in layered media. Using the fast method with patches of one wavelength dimension, the axial and lateral intensity distribution of a circular piston and a spherical cap transducer were calculated at least 20 times faster than did the conventional approach and retained numerical accuracy in near and far fields, with 2% and 5% root mean square error (RMSE) of their theoretical counterparts, respectively. Numerical examples of transmitted beam in a tissue-mimicking medium further demonstrated the efficiency and accuracy of the method. The modified scheme achieved at least 4 times computational time speed-up and had no more than 5% RMSE in comparison with the conventional approach. The fast field simulation method should be useful in transducer design and beam-forming investigation in therapeutic ultrasound applications and other scenarios where efficiency of transmitting acoustic field simulations is critical.
{"title":"P5E-9 A Fast Field Simulation Method for Longitudinal Ultrasound Wave Propagation and Transmission in Homogeneous and Layered Media","authors":"Xiangtao Yin, Shiwei Zhou, J. Petruzzello","doi":"10.1109/ULTSYM.2007.581","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.581","url":null,"abstract":"A fast Rayleigh-Sommerfeld integral-based method was presented in this paper to speed up acoustic field simulation using a modified summation scheme. Partitioning source aperture with uniform large patches instead of simple sources, the modified summation scheme outperformed the conventional simple source based approach by both reducing the number of source-field interaction pairs and reusing the beam directivity of a single source patch. This modified scheme, along with Snell's law, could also facilitate wave transmission simulation in layered media. Using the fast method with patches of one wavelength dimension, the axial and lateral intensity distribution of a circular piston and a spherical cap transducer were calculated at least 20 times faster than did the conventional approach and retained numerical accuracy in near and far fields, with 2% and 5% root mean square error (RMSE) of their theoretical counterparts, respectively. Numerical examples of transmitted beam in a tissue-mimicking medium further demonstrated the efficiency and accuracy of the method. The modified scheme achieved at least 4 times computational time speed-up and had no more than 5% RMSE in comparison with the conventional approach. The fast field simulation method should be useful in transducer design and beam-forming investigation in therapeutic ultrasound applications and other scenarios where efficiency of transmitting acoustic field simulations is critical.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"26 1","pages":"2311-2314"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89890395","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. Nakao, M. Kadota, K. Nishiyama, Y. Nakai, D. Yamamoto, Y. Ishiura, T. Komura, N. Takada, R. Kita
Using flattened-SiO2/Cu-electrode/36~48deg LiTaO3 structure, small size (5 x5mm2) surface acoustic wave (SAW) duplexer with a good temperature coefficient of frequency (TCF) for US-PCS was realized by authors. However, a smaller duplexer has been strongly required. Using flip-chip bonding process of SAW chips and Rayleigh SAW propagating on the flattened-SiO2/Cu- electrode/126~128degYX-LiNbO3, which has larger cou pling factor than above-mentioned substrate, a smaller sized (3x2.5mm2) SAW duplexer with a good TCF has been realized.
{"title":"P2H-5 Small 3x2.5mm² Sized Surface Acoustic Wave Duplexer for US-PCS with Excellent Temperature and Frequency Characteristics","authors":"T. Nakao, M. Kadota, K. Nishiyama, Y. Nakai, D. Yamamoto, Y. Ishiura, T. Komura, N. Takada, R. Kita","doi":"10.1109/ULTSYM.2007.423","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.423","url":null,"abstract":"Using flattened-SiO<sub>2</sub>/Cu-electrode/36~48deg LiTaO<sub>3</sub> structure, small size (5 x5mm<sup>2</sup>) surface acoustic wave (SAW) duplexer with a good temperature coefficient of frequency (TCF) for US-PCS was realized by authors. However, a smaller duplexer has been strongly required. Using flip-chip bonding process of SAW chips and Rayleigh SAW propagating on the flattened-SiO<sub>2</sub>/Cu- electrode/126~128degYX-LiNbO<sub>3</sub>, which has larger cou pling factor than above-mentioned substrate, a smaller sized (3x2.5mm<sup>2</sup>) SAW duplexer with a good TCF has been realized.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"64 1","pages":"1681-1684"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90287657","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}
M. Nillesen, R. Lopata, H. Gerrits, L. Kapusta, H. Huisman, J. Thijssen, C. D. de Korte
Semi-automatic segmentation of the myocardium in three-dimensional (3D) echographic images may substantially support clinical diagnosis of (congenital) heart disease. It can facilitate visualization of abnormal cardiac anatomy and may serve as an important preprocessing step for automated cardiac strain imaging. Echocardiographic image sequences of the left ventricle of two healthy subjects and one piglet were obtained in radiofrequency (RF) format, directly after beamforming, in 3D live and in Full Volume mode. To optimize the distinction between blood and myocardium, 3D Adaptive Mean Squares (AMS) filtering was performed on the demodulated rf-data. Earlier work on 2D data revealed that this filter reduces speckle noise, while preserving the sharpness of edges between various structures. In this study a 3D deformable model based on a simplex mesh was then used to segment the endocardial surface. The model deforms under influence of internal (regularization) and external (data) forces and is initialized by placing a spherical surface model in the left ventricle. A gradient and a speed force were included in the external force of the model. Weighting factors of internal, gradient and speed forces were interactively set to balance data fitting and mesh regularity. Initial results show that segmentation of the endocardial surface using 3D deformable simplex meshes in combination with adaptive filtering is feasible. The speed force led to improved segmentation in all datasets as the deformable model was less dependent on initialization. The method is promising for application to nonstandard heart geometries without having to impose strong shape constraints. To prevent the model from leaking into the left atrium or crossing areas with weak boundary information, the use of attractor forces and weak shape constraints could be helpful.
{"title":"P2A-2 Three-Dimensional Cardiac Image Segmentation Using Adaptive Filtering and 3D Deformable Simplex Meshes","authors":"M. Nillesen, R. Lopata, H. Gerrits, L. Kapusta, H. Huisman, J. Thijssen, C. D. de Korte","doi":"10.1109/ULTSYM.2007.369","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.369","url":null,"abstract":"Semi-automatic segmentation of the myocardium in three-dimensional (3D) echographic images may substantially support clinical diagnosis of (congenital) heart disease. It can facilitate visualization of abnormal cardiac anatomy and may serve as an important preprocessing step for automated cardiac strain imaging. Echocardiographic image sequences of the left ventricle of two healthy subjects and one piglet were obtained in radiofrequency (RF) format, directly after beamforming, in 3D live and in Full Volume mode. To optimize the distinction between blood and myocardium, 3D Adaptive Mean Squares (AMS) filtering was performed on the demodulated rf-data. Earlier work on 2D data revealed that this filter reduces speckle noise, while preserving the sharpness of edges between various structures. In this study a 3D deformable model based on a simplex mesh was then used to segment the endocardial surface. The model deforms under influence of internal (regularization) and external (data) forces and is initialized by placing a spherical surface model in the left ventricle. A gradient and a speed force were included in the external force of the model. Weighting factors of internal, gradient and speed forces were interactively set to balance data fitting and mesh regularity. Initial results show that segmentation of the endocardial surface using 3D deformable simplex meshes in combination with adaptive filtering is feasible. The speed force led to improved segmentation in all datasets as the deformable model was less dependent on initialization. The method is promising for application to nonstandard heart geometries without having to impose strong shape constraints. To prevent the model from leaking into the left atrium or crossing areas with weak boundary information, the use of attractor forces and weak shape constraints could be helpful.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"51 1","pages":"1468-1471"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76640626","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}
Evaluation of arterial tissue biomechanics for diagnosis and treatment of cardiovascular diseases is an active research field in the biomedical imaging processing area. Intravascular UltraSound (IVUS) is a unique tool for such assessment since it reflects tissue morphology and deformation. A proper quantification and visualization of both properties is hindered by vessel structures misalignments introduced by cardiac dynamics. This has encouraged development of IVUS motion compensation techniques. However, there is a lack of an objective evaluation of motion reduction ensuring a reliable clinical application This work reports a novel score, the Conservation of Density Rate (CDR), for validation of motion compensation in in-vivo pullbacks. Synthetic experiments validate the proposed score as measure of motion parameters accuracy; while results in in vivo pullbacks show its reliability in clinical cases.
{"title":"P5B-12 How Do Conservation Laws Define a Motion Suppression Score in In-Vivo Ivus Sequences?","authors":"Aura Hernández, Debora Gil, Albert Teis","doi":"10.1109/ULTSYM.2007.561","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.561","url":null,"abstract":"Evaluation of arterial tissue biomechanics for diagnosis and treatment of cardiovascular diseases is an active research field in the biomedical imaging processing area. Intravascular UltraSound (IVUS) is a unique tool for such assessment since it reflects tissue morphology and deformation. A proper quantification and visualization of both properties is hindered by vessel structures misalignments introduced by cardiac dynamics. This has encouraged development of IVUS motion compensation techniques. However, there is a lack of an objective evaluation of motion reduction ensuring a reliable clinical application This work reports a novel score, the Conservation of Density Rate (CDR), for validation of motion compensation in in-vivo pullbacks. Synthetic experiments validate the proposed score as measure of motion parameters accuracy; while results in in vivo pullbacks show its reliability in clinical cases.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"1 1","pages":"2231-2234"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78057551","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}
O. Elmazria, F. Bénédic, M. B. Assouar, D. Monéger, L. Le Brizoual, A. Gicquel, P. Alnot
In this work nanocrystalline diamond (NCD) was investigated as high velocity and low propagation loss substrate for SAW devices. The considered layered structure is AIN/NCD/Silicon. First the 16 mum of (110)-oriented NCD films were grown on <100>-oriented silicon substrates of approximately 2.5 cm2 in size. Smooth piezoelectric AIN films with columnar structure and (002) orientation were then deposited on the NCD surface. The AIN film thickness was fixed to 1 mum and the spatial periodicity of IDT to 20 mum. The operating frequency of the realized device was measured at 645 MHz. This shows that surface acoustic waves being propagated at the velocity of 13 km/s were generated in this structure. The obtained velocity value is a quite higher than the value obtained by calculation when elastic constants of polycrystalline are used.
{"title":"4E-3 Very High Surface Acoustic Wave Velocity on the Layered Structure Formed of Aluminium Nitride on Nanocrystalline Diamond on Silicon","authors":"O. Elmazria, F. Bénédic, M. B. Assouar, D. Monéger, L. Le Brizoual, A. Gicquel, P. Alnot","doi":"10.1109/ULTSYM.2007.80","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.80","url":null,"abstract":"In this work nanocrystalline diamond (NCD) was investigated as high velocity and low propagation loss substrate for SAW devices. The considered layered structure is AIN/NCD/Silicon. First the 16 mum of (110)-oriented NCD films were grown on <100>-oriented silicon substrates of approximately 2.5 cm2 in size. Smooth piezoelectric AIN films with columnar structure and (002) orientation were then deposited on the NCD surface. The AIN film thickness was fixed to 1 mum and the spatial periodicity of IDT to 20 mum. The operating frequency of the realized device was measured at 645 MHz. This shows that surface acoustic waves being propagated at the velocity of 13 km/s were generated in this structure. The obtained velocity value is a quite higher than the value obtained by calculation when elastic constants of polycrystalline are used.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"126 1","pages":"276-279"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78543933","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}
Detection of bone surfaces in ultrasound images would be useful for ultrasound guided orthopedic surgery, biopsy and brachytherapy. However, bones are often poorly visualized with conventional B-mode ultrasound due to speckle, shadowing, reverberation and other artifacts in tissue. In this paper, we investigate two new techniques for the enhancement of bone surface visualization using ultrasound radio frequency (RF) signals, instead of using conventional B-mode images. The first approach uses strain imaging or elastography, and the second method directly monitors the reflected power of the RF signal. The potential of the proposed methods is demonstrated through phantom and in vivo experiments. Experimental results show that the two methods produce satisfactory contrast between bone surfaces and soft tissue, and are suitable for real-time applications. The good performance of these approaches suggests that they have promise in a clinical setting.
{"title":"P6D-5 Enhancement of Bone Surface Visualization Using Ultrasound Radio-Frequency Signals","authors":"Xu Wen, S. Salcudean","doi":"10.1109/ULTSYM.2007.638","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.638","url":null,"abstract":"Detection of bone surfaces in ultrasound images would be useful for ultrasound guided orthopedic surgery, biopsy and brachytherapy. However, bones are often poorly visualized with conventional B-mode ultrasound due to speckle, shadowing, reverberation and other artifacts in tissue. In this paper, we investigate two new techniques for the enhancement of bone surface visualization using ultrasound radio frequency (RF) signals, instead of using conventional B-mode images. The first approach uses strain imaging or elastography, and the second method directly monitors the reflected power of the RF signal. The potential of the proposed methods is demonstrated through phantom and in vivo experiments. Experimental results show that the two methods produce satisfactory contrast between bone surfaces and soft tissue, and are suitable for real-time applications. The good performance of these approaches suggests that they have promise in a clinical setting.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"110 1","pages":"2535-2538"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75031758","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. Meulendyk, M. C. Wheeler, B. Segee, M. Pereira da Cunha
Hydrogen fluoride (HF) is a hazardous compound used in a variety of industrial processes and is a decomposition product of many other fluorinated volatile organic compounds (VOCs), which are often environmental contaminants. Surface acoustic wave (SAW) resonators on quartz substrates are suited for HF sensing because the analyte can react directly with the sensor substrate to produce H2O and the volatile compound SiF4, which evaporates from the surface. This work shows evidence that during gas phase HF exposure to a generalized SAW (GSAW) resonator and a pure shear horizontal SAW (SHSAW) resonator, the dominant sensing mechanism is the detection of a condensed liquid layer on the substrate surface, rather than material removal via SiF4 desorption. The GSAW and SHSAW, fabricated on ST-X and ST-900 quartz, respectively, have been simultaneously exposed to HF through a low-volume (~1 cm ) test cell. The devices' responses were monitored, with data collected every minute. An automated gas delivery system was used to vary HF concentrations from 1-18 ppm, while maintaining a constant flow rate of 100 seem. While both resonators are sensitive to the formation of a condensed liquid layer, the frequency shift of the SHSAW resonator, due to this effect, is up to seven times greater than that of the GSAW device for the HF concentrations investigated.
{"title":"6D-4 Generalized and Pure Shear Horizontal SAW Sensors on Quartz for Hydrogen Fluoride Gas Detection","authors":"B. Meulendyk, M. C. Wheeler, B. Segee, M. Pereira da Cunha","doi":"10.1109/ULTSYM.2007.129","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.129","url":null,"abstract":"Hydrogen fluoride (HF) is a hazardous compound used in a variety of industrial processes and is a decomposition product of many other fluorinated volatile organic compounds (VOCs), which are often environmental contaminants. Surface acoustic wave (SAW) resonators on quartz substrates are suited for HF sensing because the analyte can react directly with the sensor substrate to produce H2O and the volatile compound SiF4, which evaporates from the surface. This work shows evidence that during gas phase HF exposure to a generalized SAW (GSAW) resonator and a pure shear horizontal SAW (SHSAW) resonator, the dominant sensing mechanism is the detection of a condensed liquid layer on the substrate surface, rather than material removal via SiF4 desorption. The GSAW and SHSAW, fabricated on ST-X and ST-900 quartz, respectively, have been simultaneously exposed to HF through a low-volume (~1 cm ) test cell. The devices' responses were monitored, with data collected every minute. An automated gas delivery system was used to vary HF concentrations from 1-18 ppm, while maintaining a constant flow rate of 100 seem. While both resonators are sensitive to the formation of a condensed liquid layer, the frequency shift of the SHSAW resonator, due to this effect, is up to seven times greater than that of the GSAW device for the HF concentrations investigated.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"113 1","pages":"480-483"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75334087","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}
A. Agarwal, T. Fukuoka, F. Schneider, Y. Yoo, F. Baluyot, Yongmin Kim
Traditionally, application-specific integrated circuits (ASICs) are used for supporting the computational and data rate requirements of medical ultrasound systems. Utilizing the previously-developed efficient front-end algorithms and the continuing advances in solid state devices, we developed a hybrid programmable architecture to support core ultrasound signal processing. With the advent of new- generation digital signal processors (DSPs) (e.g., Texas Instruments' TMS320C6455 and IBM's Cell Broadband Engine), this hybrid field programmable gate array (FPGA)- DSP architecture can evolve towards a single-chip solution after overcoming the following challenges: (a) inefficient data access during dynamic focusing and (b) multiple, parallel data- transfer paths from ADCs. In this paper, we present a new single-DSP architecture, where an advanced DSP handles all the front- and back-end processing in software. To enable this new architecture, we have (a) developed a new stepwise dynamic focusing method, where the same delay curve is utilized for a group of samples along the depth direction and (b) investigated use of serial interfaces for ADC to DSP data transfer. It was found that the TMS320C6455 can meet the requirements of a 32-channel B-mode imaging system using 56.6% and 85.4% of the computing and serial I/O resources of the DSP, respectively. These results indicate that a single DSP chip solution can meet the hardware requirements for lower-end medical ultrasound systems.
{"title":"P2B-17 Single-Chip Solution for Ultrasound Imaging Systems: Initial Results","authors":"A. Agarwal, T. Fukuoka, F. Schneider, Y. Yoo, F. Baluyot, Yongmin Kim","doi":"10.1109/ULTSYM.2007.393","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.393","url":null,"abstract":"Traditionally, application-specific integrated circuits (ASICs) are used for supporting the computational and data rate requirements of medical ultrasound systems. Utilizing the previously-developed efficient front-end algorithms and the continuing advances in solid state devices, we developed a hybrid programmable architecture to support core ultrasound signal processing. With the advent of new- generation digital signal processors (DSPs) (e.g., Texas Instruments' TMS320C6455 and IBM's Cell Broadband Engine), this hybrid field programmable gate array (FPGA)- DSP architecture can evolve towards a single-chip solution after overcoming the following challenges: (a) inefficient data access during dynamic focusing and (b) multiple, parallel data- transfer paths from ADCs. In this paper, we present a new single-DSP architecture, where an advanced DSP handles all the front- and back-end processing in software. To enable this new architecture, we have (a) developed a new stepwise dynamic focusing method, where the same delay curve is utilized for a group of samples along the depth direction and (b) investigated use of serial interfaces for ADC to DSP data transfer. It was found that the TMS320C6455 can meet the requirements of a 32-channel B-mode imaging system using 56.6% and 85.4% of the computing and serial I/O resources of the DSP, respectively. These results indicate that a single DSP chip solution can meet the hardware requirements for lower-end medical ultrasound systems.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"4 1","pages":"1563-1566"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75828943","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}
A simulation study is performed to present results concerning 3D aberration correction for harmonic imaging. Two different correction schemes (a pure time-delay correction and a time-delay and amplitude correction) are employed along with estimation based on either the received first- or second-harmonic frequency. An aberrating body wall is implemented as a 20 mm delay-screen body wall using eight screens, and is tuned to match human abdominal wall characteristics. The transmit pressure of the first harmonic is set to not succeed a mechanical index of 1.1 for the uncorrected case and a pure time-delay correction. Using a time-delay and amplitude correction, the total acoustic energy transmitted is equal to that of the uncorrected case. The total amount of generated second-harmonic energy increases with approximately 1 dB for a pure time-delay correction and about 2 dB for a time-delay and amplitude correction, both estimated at the received first-harmonic frequency. The general side-lobe level of the first- and second-harmonic focal point beam profile averaged over circles around the transducer axis is lowered with 2-10 dB for both correction schemes relative to the uncorrected case.
{"title":"P2B-10 Second-Harmonic Aberration Correction","authors":"H. Kaupang, T. Varslot, S. Måsøy","doi":"10.1109/ULTSYM.2007.387","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.387","url":null,"abstract":"A simulation study is performed to present results concerning 3D aberration correction for harmonic imaging. Two different correction schemes (a pure time-delay correction and a time-delay and amplitude correction) are employed along with estimation based on either the received first- or second-harmonic frequency. An aberrating body wall is implemented as a 20 mm delay-screen body wall using eight screens, and is tuned to match human abdominal wall characteristics. The transmit pressure of the first harmonic is set to not succeed a mechanical index of 1.1 for the uncorrected case and a pure time-delay correction. Using a time-delay and amplitude correction, the total acoustic energy transmitted is equal to that of the uncorrected case. The total amount of generated second-harmonic energy increases with approximately 1 dB for a pure time-delay correction and about 2 dB for a time-delay and amplitude correction, both estimated at the received first-harmonic frequency. The general side-lobe level of the first- and second-harmonic focal point beam profile averaged over circles around the transducer axis is lowered with 2-10 dB for both correction schemes relative to the uncorrected case.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"69 1","pages":"1537-1540"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74549950","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}
L. De Marchi, A. Palladini, N. Testoni, N. Speciale
Biomedical ultrasound (US) image quality is limited due to the blurring of tissue reflectivity introduced by the transducer Point Spread Function (PSF). We present a method based on a Maximum Likelihood (ML) estimation of tissue response. We adopt efficient equalization techniques usually applied in digital communications: the ultrasonic RF signal is considered as a sequence of discrete values (symbols) affected by channel intersymbol interference (ISI), and processed with a reduced-complexity Viterbi algorithm. Spatial variations of the channel are then tracked by coupling the Viterbi algorithm with a least mean square (LMS) real-time updating procedure. Finally, an adaptive symbol-quantization is defined to overcome the qualitative limitation due to a finite-length alphabet. The results show that the fast LMS adaptation of the channel allows for a real-time spatial analysis and compensation of tissue attenuation effects and inhomogeneities, thus enhancing the diagnostic capability of US images.
{"title":"P1A-8 Blurred Ultrasonic Images as ISI-Affected Signals: Joint Tissue Response Estimation and Channel Tracking in the Proposed Paradigm","authors":"L. De Marchi, A. Palladini, N. Testoni, N. Speciale","doi":"10.1109/ULTSYM.2007.319","DOIUrl":"https://doi.org/10.1109/ULTSYM.2007.319","url":null,"abstract":"Biomedical ultrasound (US) image quality is limited due to the blurring of tissue reflectivity introduced by the transducer Point Spread Function (PSF). We present a method based on a Maximum Likelihood (ML) estimation of tissue response. We adopt efficient equalization techniques usually applied in digital communications: the ultrasonic RF signal is considered as a sequence of discrete values (symbols) affected by channel intersymbol interference (ISI), and processed with a reduced-complexity Viterbi algorithm. Spatial variations of the channel are then tracked by coupling the Viterbi algorithm with a least mean square (LMS) real-time updating procedure. Finally, an adaptive symbol-quantization is defined to overcome the qualitative limitation due to a finite-length alphabet. The results show that the fast LMS adaptation of the channel allows for a real-time spatial analysis and compensation of tissue attenuation effects and inhomogeneities, thus enhancing the diagnostic capability of US images.","PeriodicalId":6355,"journal":{"name":"2007 IEEE Ultrasonics Symposium Proceedings","volume":"110 1","pages":"1270-1273"},"PeriodicalIF":0.0,"publicationDate":"2007-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74651461","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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