Proceedings. IEEE Ultrasonics Symposium最新文献

{"title":"C-plane Reconstructions from Sheaf Acquisition for Ultrasound Electrode Vibration Elastography.","authors":"Atul Ingle,&nbsp;Tomy Varghese","doi":"10.1109/ULTSYM.2014.0453","DOIUrl":"https://doi.org/10.1109/ULTSYM.2014.0453","url":null,"abstract":"<p><p>This paper presents a novel algorithm for reconstructing and visualizing ablated volumes using radiofrequency ultrasound echo data acquired with the electrode vibration elastography approach. The ablation needle is vibrated using an actuator to generate shear wave pulses that are tracked in the ultrasound image plane at different locations away from the needle. This data is used for reconstructing shear wave velocity maps for each imaging plane. A C-plane reconstruction algorithm is proposed which estimates shear wave velocity values on a collection of transverse planes that are perpendicular to the imaging planes. The algorithm utilizes shear wave velocity maps from different imaging planes that share a common axis of intersection. These C-planes can be used to generate a 3D visualization of the ablated region. Experimental validation of this approach was carried out using data from a tissue mimicking phantom. The shear wave velocity estimates were within 20% of those obtained from a clinical scanner, and a contrast of over 4 dB was obtained between the stiff and soft regions of the phantom.</p>","PeriodicalId":89469,"journal":{"name":"Proceedings. IEEE Ultrasonics Symposium","volume":"2014 ","pages":"1826-1829"},"PeriodicalIF":0.0,"publicationDate":"2014-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1109/ULTSYM.2014.0453","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32925282","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}

{"title":"FEA of CMUTs Suitable for Wide Gas Pressure Range Applications.","authors":"Min-Chieh Ho, Mario Kupnik, Butrus T Khuri-Yakub","doi":"10.1109/ULTSYM.2010.5935678","DOIUrl":"10.1109/ULTSYM.2010.5935678","url":null,"abstract":"<p><p>The ability of ultrasound transducers to operate over a wide and varying pressure range is essential in applications such as ultrasonic flow metering (UFM) of flare gas. We propose a new operational mode for capacitive micromachined ultrasonic transducers (CMUTs), in which the plate is in permanent contact with the bottom of the cavity, even at zero DC bias and 1 atm pressure. Finite element analysis (FEA) software was used to investigate the performance of these CMUTs within the pressure range of 1 to 20 atm. First, we performed a static analysis to determine the plate deflection and, thus, the gap height. Further, from the static analysis, we obtained the static and free capacitances for calculating the coupling efficiency, and a modal analysis identified possible design geometries for frequencies lower than ~ 300 kHz. Our calculations show that conventionally operated CMUTs have huge changes in static operational point at different pressures, while our proposed mode exhibits an acceptable frequency range (73 - 340 kHz) over 1 - 20 atm pressure and an improved coupling efficiency at lower dc bias voltages. A donut shape partial electrode further allows us to tune the coupling efficiency, which translates into a better performance, especially at the higher pressure range. FEA shows that our proposed operation mode is a promising solution for flare gas metering applications.</p>","PeriodicalId":89469,"journal":{"name":"Proceedings. IEEE Ultrasonics Symposium","volume":"2010 ","pages":"1234-1237"},"PeriodicalIF":0.0,"publicationDate":"2010-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3160643/pdf/nihms255132.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"29961679","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}

{"title":"Modeling and Measuring the Effects of Mutual Impedance on Multi-Cell CMUT Configurations.","authors":"K K Park, M Kupnik, H J Lee, B T Khuri-Yakub, I O Wygant","doi":"10.1109/ULTSYM.2010.5936010","DOIUrl":"10.1109/ULTSYM.2010.5936010","url":null,"abstract":"<p><p>This paper presents a numerical method for calculating the frequency response of a CMUT with a large number of cells. In a multi-cell configuration, commonly found in CMUTs, each cell is affected by the acoustic loading from neighboring cells. Thus, for an accurate model of a multi-cell CMUT element it is better to consider the mutual acoustic impedance instead of the acoustic impedance of a single cell only. We calculate the velocity of every cell (plate movement) simultaneously, with the mutual impedance effects taken into account. The model predicts that the cells exhibit different frequency responses, based on their locations in the element. We used a laser interferometer to validate the model by measuring the displacement response of a CMUT immersed in vegetable oil. The device has 169 circular cells (single crystal silicon plates, 500 nm thick, 21 μm radii) placed in a hexagonal cell arrangement. The measurement results agree well with the numerical results. The computation time of our method is significantly shorter than finite element based calculations. Our model can be used for finding optimized cell configurations for CMUTs utilized in various applications such as medical imaging and therapeutic treatment.</p>","PeriodicalId":89469,"journal":{"name":"Proceedings. IEEE Ultrasonics Symposium","volume":"2010 ","pages":"431-434"},"PeriodicalIF":0.0,"publicationDate":"2010-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3150120/pdf/nihms255134.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"30060719","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}

{"title":"Design Optimization for a 2-D Sparse Transducer Array for 3-D Ultrasound Imaging.","authors":"Jung Woo Choe, Omer Oralkan, Pierre T Khuri-Yakub","doi":"10.1109/ULTSYM.2010.5935854","DOIUrl":"10.1109/ULTSYM.2010.5935854","url":null,"abstract":"<p><p>In 3-D ultrasound imaging where 2-D transducer arrays with more than hundreds of elements are used, sparse arrays can be used to reduce the number of active ultrasound channels. Under a restriction of desired number of active channels, we can maximize the image quality by optimally choosing the positions of active elements. Here we use the method of simulated annealing to find the optimal configuration of a 2-D sparse array. This algorithm tries to minimize the value of an objective function defined as the energy ratio between the nonfocal and focal regions in the point spread function (PSF). Optimal configurations were found for the cases of choosing 16, 20, 24, 28, and 32 transmit and receive elements from a 16×16-element rectangular transducer array. With only 32 transmit and 32 receive elements, we could achieve an energy ratio of 16%, compared to 6% of the full array, which is the gold standard utilizing all the 256 elements for both transmit and receive. Using Field II, we simulated imaging with the optimal sparse arrays, for off-axis targets as well as on-axis targets, and the resulting images were compared with those from some other configurations, such as full-transmit full-receive, full-transmit x-receive, x-transmit boundary-receive, and so on.</p>","PeriodicalId":89469,"journal":{"name":"Proceedings. IEEE Ultrasonics Symposium","volume":"2010 ","pages":"1928-1931"},"PeriodicalIF":0.0,"publicationDate":"2010-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3150118/pdf/nihms255128.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"29916744","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}

{"title":"Acoustic Droplet Vaporization for the Enhancement of Ultrasound Thermal Therapy.","authors":"Man Zhang, Mario Fabiilli, Paul Carson, Frederic Padilla, Scott Swanson, Oliver Kripfgans, Brian Fowlkes","doi":"10.1109/ULTSYM.2010.0054","DOIUrl":"10.1109/ULTSYM.2010.0054","url":null,"abstract":"<p><p>Acoustic droplet vaporization (ADV) is an ultrasound method for converting biocompatible microdroplets into microbubbles. The objective is to demonstrate that ADV bubbles can enhance high intensity focused ultrasound (HIFU) therapy by controlling and increasing energy absorption at the focus. Thermal phantoms were made with or without droplets. Compound lesions were formed in the phantoms by 5-second exposures with 5-second delays. Center to center spacing of individual lesions was 5.5 mm in either a linear pattern or a spiral pattern. Prior to the HIFU, 10 cycle tone bursts with 0.25% duty cycle were used to vaporize the droplets, forming an \"acoustic trench\" within 30 seconds. The transducer was then focused in the middle of the back bubble wall to form thermal lesions in the trench. All lesions were imaged optically and with 2T MRI. With the use of ADV and the acoustic trench, a uniform thermal ablation volume of 15 cm(3) was achieved in 4 minutes; without ADV only less than 15% of this volume was filled. The commonly seen tadpole shape characteristic of bubble-enhanced HIFU lesions was not evident with the acoustic trench. In conclusion, ADV shows promise for the spatial control and dramatic acceleration of thermal lesion production by HIFU.</p>","PeriodicalId":89469,"journal":{"name":"Proceedings. IEEE Ultrasonics Symposium","volume":"2010 ","pages":"221-224"},"PeriodicalIF":0.0,"publicationDate":"2010-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3145358/pdf/nihms-284092.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"29903229","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}

{"title":"3-D Deep Penetration Photoacoustic Imaging with a 2-D CMUT Array.","authors":"Te-Jen Ma, Sri Rajasekhar Kothapalli, Srikant Vaithilingam, Omer Oralkan, Aya Kamaya, Ira O Wygant, Xuefeng Zhuang, Sanjiv S Gambhir, R Brooke Jeffrey, Butrus T Khuri-Yakub","doi":"10.1109/ULTSYM.2010.5935647","DOIUrl":"10.1109/ULTSYM.2010.5935647","url":null,"abstract":"<p><p>In this work, we demonstrate 3-D photoacoustic imaging of optically absorbing targets embedded as deep as 5 cm inside a highly scattering background medium using a 2-D capacitive micromachined ultrasonic transducer (CMUT) array with a center frequency of 5.5 MHz. 3-D volumetric images and 2-D maximum intensity projection images are presented to show the objects imaged at different depths. Due to the close proximity of the CMUT to the integrated frontend circuits, the CMUT array imaging system has a low noise floor. This makes the CMUT a promising technology for deep tissue photoacoustic imaging.</p>","PeriodicalId":89469,"journal":{"name":"Proceedings. IEEE Ultrasonics Symposium","volume":"2010 ","pages":"375-377"},"PeriodicalIF":0.0,"publicationDate":"2010-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3438520/pdf/nihms255135.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"30906065","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}

{"title":"CMUT Fabrication Based On A Thick Buried Oxide Layer.","authors":"Mario Kupnik, Srikant Vaithilingam, Kazutoshi Torashima, Ira O Wygant, Butrus T Khuri-Yakub","doi":"10.1109/ULTSYM.2010.5935935","DOIUrl":"10.1109/ULTSYM.2010.5935935","url":null,"abstract":"<p><p>We introduce a versatile fabrication process for direct wafer-bonded CMUTs. The objective is a flexible fabrication platform for single element transducers, 1D and 2D arrays, and reconfigurable arrays. The main process features are: A low number of litho masks (five for a fully populated 2D array); a simple fabrication sequence on standard MEMS tools without complicated wafer handling (carrier wafers); an improved device reliability; a wide design space in terms of operation frequency and geometric parameters (cell diameter, gap height, effective insulation layer thickness); and a continuous front face of the transducer (CMUT plate) that is connected to ground (shielding for good SNR and human safety in medical applications). All of this is achieved by connecting the hot electrodes individually through a thick buried oxide layer, i.e. from the handle layer of an SOI substrate to silicon electrodes located in each CMUT cell built in the device layer. Vertical insulation trenches are used to isolate these silicon electrodes from the rest of the substrate. Thus, the high electric field is only present where required - in the evacuated gap region of the device and not in the insulation layer of the post region. Array elements (1D and 2D) are simply defined be etching insulation trenches into the handle wafer of the SOI substrate.</p>","PeriodicalId":89469,"journal":{"name":"Proceedings. IEEE Ultrasonics Symposium","volume":"2010 ","pages":"547-550"},"PeriodicalIF":0.0,"publicationDate":"2010-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3370668/pdf/nihms255125.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"30680749","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}

{"title":"CMUT With Substrate-Embedded Springs For Non-Flexural Plate Movement.","authors":"Amin Nikoozadeh, Pierre T Khuri-Yakub","doi":"10.1109/ULTSYM.2010.5936014","DOIUrl":"10.1109/ULTSYM.2010.5936014","url":null,"abstract":"<p><p>A conventional capacitive micromachined ultrasonic transducer (CMUT) is composed of many cells connected in parallel. Since the plate in each CMUT cell is anchored at its perimeter, the average displacement is several times smaller than the displacement of an equivalent ideal piston transducer. In addition, the post areas, where the plates are anchored to, are non-active and, thus, do not contribute to the transduction. We propose a CMUT structure that resembles an ideal capacitive piston transducer, where the movable top plate only undergoes translation rather than deflection. Our proposed CMUT structure is composed of a rigid plate connected to a substrate using relatively long and narrow posts, providing the spring constant for the movement of the plate. Rather than the flexure of the plate as in a conventional CMUT, this device operates based on the compression of the compliant posts. For a capacitive transducer, a thin electrostatic gap is provided under the top plate. We used finite element analysis (FEA) to design and verify the structure's functionality. The simulation results show a fractional bandwidth of over 100% in immersion for all the designs. They also confirm that the average displacement of the top plate is above 90% of its peak displacement. We fabricated the first prototype based on this idea, which only requires a simple 3-mask fabrication process. In addition to 128-element 1-D arrays, we fabricated a variety of 240 μm × 240 μm, single-element transducers with different post configurations. We successfully measured the electrical input impedance of the fabricated devices and confirmed their resonant behavior in air. Further, we measured the acoustic pressure using a calibrated hydrophone at a known distance. Using this measurement, we calculated a peak-to-peak pressure of 1.5 MPa at the face of the transducer. Our results show that it is possible to fabricate CMUTs that exhibit ideal piston-like plate movement. Because of the substrate-embedded spring elements, the plate does not need to be operated in flexural mode, as in a conventional CMUT, resulting in a significantly improved fill-factor, and, thus, a more efficient device.</p>","PeriodicalId":89469,"journal":{"name":"Proceedings. IEEE Ultrasonics Symposium","volume":"2010 ","pages":"1510-1513"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4175474/pdf/nihms-255123.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32704037","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}

{"title":"Decomposition of Two-Component Pulses in Bone: Phantom Experiment and Simulation.","authors":"Keith A Wear","doi":"10.1109/ultsym.2010.5935641","DOIUrl":"10.1109/ultsym.2010.5935641","url":null,"abstract":"<p><p>Prony's method is used to separate signals that overlap in time domain. For additional information, the reader is referred to the references at the end of this paper.</p>","PeriodicalId":89469,"journal":{"name":"Proceedings. IEEE Ultrasonics Symposium","volume":"NA ","pages":"723"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9210505/pdf/nihms-1815680.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40217853","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}

{"title":"Development of a Multi-modal Tissue Diagnostic System Combining High Frequency Ultrasound and Photoacoustic Imaging with Lifetime Fluorescence Spectroscopy.","authors":"Yang Sun, Douglas N Stephens, Jesung Park, Yinghua Sun, Laura Marcu, Jonathan M Cannata, K Kirk Shung","doi":"10.1109/ULTSYM.2008.0137","DOIUrl":"10.1109/ULTSYM.2008.0137","url":null,"abstract":"<p><p>We report the development and validate a multi-modal tissue diagnostic technology, which combines three complementary techniques into one system including ultrasound backscatter microscopy (UBM), photoacoustic imaging (PAI), and time-resolved laser-induced fluorescence spectroscopy (TR-LIFS). UBM enables the reconstruction of the tissue microanatomy. PAI maps the optical absorption heterogeneity of the tissue associated with structure information and has the potential to provide functional imaging of the tissue. Examination of the UBM and PAI images allows for localization of regions of interest for TR-LIFS evaluation of the tissue composition. The hybrid probe consists of a single element ring transducer with concentric fiber optics for multi-modal data acquisition. Validation and characterization of the multi-modal system and ultrasonic, photoacoustic, and spectroscopic data coregistration were conducted in a physical phantom with properties of ultrasound scattering, optical absorption, and fluorescence. The UBM system with the 41 MHz ring transducer can reach the axial and lateral resolution of 30 and 65 μm, respectively. The PAI system with 532 nm excitation light from a Nd:YAG laser shows great contrast for the distribution of optical absorbers. The TR-LIFS system records the fluorescence decay with the time resolution of ~300 ps and a high sensitivity of nM concentration range. Biological phantom constructed with different types of tissues (tendon and fat) was used to demonstrate the complementary information provided by the three modalities. Fluorescence spectra and lifetimes were compared to differentiate chemical composition of tissues at the regions of interest determined by the coregistered high resolution UBM and PAI image. Current results demonstrate that the fusion of these techniques enables sequentially detection of functional, morphological, and compositional features of biological tissue, suggesting potential applications in diagnosis of tumors and atherosclerotic plaques.</p>","PeriodicalId":89469,"journal":{"name":"Proceedings. IEEE Ultrasonics Symposium","volume":" ","pages":"570-573"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3164263/pdf/nihms112519.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"30121728","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}