A5059230496- Ultrasound Imaging and Elastography
- Ultrasonics and Acoustic Wave Propagation
- Ultrasound and Hyperthermia Applications
- Photoacoustic and Ultrasonic Imaging
- Wireless Power Transfer Systems
- Electrical and Bioimpedance Tomography
- Flow Measurement and Analysis
- Gastrointestinal Bleeding Diagnosis and Treatment
- Gastrointestinal disorders and treatments
- Acoustic Wave Phenomena Research
- Acoustic Wave Resonator Technologies
- Cardiac Arrhythmias and Treatments
- Thermography and Photoacoustic Techniques
- Cardiovascular Health and Disease Prevention
- Infrared Thermography in Medicine
- Advanced MRI Techniques and Applications
- GaN-based semiconductor devices and materials
- Non-Destructive Testing Techniques
- Cerebrovascular and Carotid Artery Diseases
- Radio Frequency Integrated Circuit Design
Stanford University
2015-2019
Palo Alto University
2019
Technical University of Denmark
2012-2015
Laboratoire d’Imagerie Biomédicale
2014
University of Copenhagen
2013
The Synthetic Aperture Real-time Ultrasound System (SARUS) for acquiring and processing synthetic aperture (SA) data research purposes is described. specifications design of the system are detailed, along with its performance SA, nonlinear, 3-D flow estimation imaging. SARUS acquires individual channel simultaneously up to 1024 transducer elements a couple heart beats, capable transmitting any kind excitation. 64 boards in house 16 transmit receive channels each, where sampled can be stored...
This paper investigates the effect of transducerintegrated apodization in row-column-addressed arrays and presents a beamforming approach specific for such arrays. Row-column addressing 2-D greatly reduces number active channels needed to acquire 3-D volume. A disadvantage is an apparent ghost point spread function caused by edge waves. origin waves introducing integrated reduce echoes. The performance λ/2-pitch 5-MHz 128 + array with different apodizations simulated. Hann shown decrease...
Transrectal ultrasound and photoacoustic imaging simultaneously provide structural molecular contrasts of normal cancerous human prostates.
This paper demonstrates the fabrication, characterization, and experimental imaging results of a 62+62 element λ/2-pitch row-column-addressed capacitive micromachined ultrasonic transducer (CMUT) array with integrated apodization. A new fabrication process was used to manufacture 26.3 mm by using five lithography steps. The includes an apodization, presented in detail Part I this paper, which is designed reduce amplitude ghost echoes that are otherwise prominent for arrays. Custom front-end...
A real-time 3-D ultrasound measurement using only 32 elements and emissions is presented. The imaging quality compared to a conventionally fully addressed array 1024 256 emissions. main-lobe of the measured line spread function almost identical, but side-lobe levels are higher for row-column array. cystic resolution sampled at relative intensity difference 20 dB shows cyst size 5.00mm 2.39mm simulation study carried out which compares how two addressing methods scales with number beamforming...
The 3-D transverse oscillation method is investigated by estimating velocities in an experimental flow-rig system. Measurements of the synthesized oscillating fields are presented as well. employs a 2-D transducer; decouples velocity estimation; and estimates axial, transverse, elevation components simultaneously. Data acquired using research ultrasound scanner. measurements conducted with steady flow sixteen different directions. For specific direction [α, ß] = [45, 15]°, mean estimated...
This paper demonstrates that synthetic aperture imaging (SAI) can be used to achieve real-time 3-D ultrasound phased-array imaging. It investigates whether SAI increases the image quality compared with parallel beamforming (PB) technique for Data are obtained using both simulations and measurements an research scanner a commercially available 3.5- MHz 1024-element 2-D transducer array. To limit probe cable thickness, 256 active elements in transmit receive techniques. The two techniques were...
This paper compares the imaging performance of a 128+128 element row-column addressed array with fully 16×16 2D array. The comparison is made via simulations point spread function Field II. Both arrays have lambda-pitch, center frequency 3:5MHz and use 256 active elements. uses 128 transmit channels receive channels, whereas in both receive. large size emulated row column elements causes ghost echoes to appear. are shown be suppressed when sub-elements within each apodized. maximum...
A method for rapid measurement of intensities (Ispta), mechanical index (MI), and probe surface temperature any ultrasound scanning sequence is presented. It uses the scanner's sampling capability to give an accurate whole imaging all emissions yield true distributions. The several orders magnitude faster than approaches using oscilloscope, it also facilitates validating emitted pressure field emission software. has been implemented experimental synthetic aperture real-time system (SARUS)...
Successful high intensity focused ultrasound (HIFU) operation requires a reliable guidance and monitoring method such as magnetic resonance imaging (MRI) or imaging. However, both widely used modalities are typically separate from the HIFU system, which makes co-registration of with cross-sectional difficult. In this paper, we present dual-mode integrated circuit (IC) that can perform single 2D capacitive micromachined ultrasonic transducer (CMUT) array, combining these two systems for ease...
We are developing a capsule ultrasound (CUS) device - pill with the capability to scan gastrointestinal (GI) tract through ultrasound. In this paper, we discuss design and fabrication of main components CUS including CMUT array, front-end electronics, wireless transmitter. demonstrate successfully fabricated 128-element array polydimethylsiloxane (PDMS)-filled trenches show their input impedance in air. The measuring 6 mm by high-data rate transmitter, 1 1.76 mm, have been fabricated. Our...
We are developing a capsule ultrasound (CUS) device to serve as wireless, portable, and ultrasonic pill for investigating the multiple layers of complete gastrointestinal (GI) tract, in particular, small intestine. This will acquire images with 360 degrees field-of-view (FOV) penetration depth 5 cm using 128-element cylindrically-shaped capacitive micromachined transducer (CMUT) array, wrapped around center its body. Simulation results indicate that linear array imaging fixed focus F#4 16...
To overcome the limitations of conventional ultrasound endoscopy, we developed a capsule (CUS) device: an ingestible and disposable pill to inspect multiple layers entire gastrointestinal (GI) tract provide convenient method for diagnosing GI diseases. The CUS device was composed three building blocks: cylindrical capacitive micromachined ultrasonic transducer (CMUT) array, imaging circuitry, wireless transmitter. All these components were designed, fabricated tested successfully. With low...
Experimental results from row-column addressed capacitive micromachined ultrasonic transducers (CMUTs) with integrated apodization are presented. The is applied by varying the density of CMUT cells in array objective damping edge waves originating element ends. Two 32+32 arrays produced using a wafer-bonding technique, one and without apodization. Hydrophone measurements emitted pressure field show reduction wave energy 8.4 dB (85 %) compared to Field II simulations yield corresponding 13.0...
In order to overcome the limitations of conventional ultrasound endoscope, we propose develop a capsule (CUS) device: an ingestible and disposable pill inspect multiple layers entire gastrointestinal (GI) tract as well its surrounding organs, provide convenient method for diagnosing GI diseases, such abdominal cancers lesions. The CUS device is composed three building blocks: cylindrical capacitive micromachined ultrasonic transducer (CMUT) array, front-end electronics, wireless transmitter....
Image-guided high-intensity focused ultrasound (HIFU) is widely used not only for non-invasive therapy but also a precise approach tissue ablation. Most HIFU systems use piezoelectric transducers, which are typically bulky due to active cooling, and separate imaging therefore impractical catheter-based applications. Taking advantage of single 2-D capacitive micromachined ultrasonic transducer (CMUT) array, we developed dual-mode catheter that can switch between mode ablation mode. The...
FDA requires that intensity and safety parameters are measured for all imaging schemes clinical imaging. This is often cumbersome, since the scan sequence has to broken apart, measurements conducted individually emitted beams, final levels calculated by combining intensities from individual beams. paper suggests a fast measurement scheme using multi-line sampling capability of modern scanners research systems. The hydrophone connected one channel in system, lines emission sequence. makes it...
The concept of 2-D row-column (RC) addressed arrays for 3-D imaging have shown to be an interesting alternative matrix array, due the reduced channel count. However, properties RC estimate blood velocities never been reported, which is great importance a clinical implementation this type array. aim study is, thus, develop technique estimating vector flow with array using transverse oscillation (TO) method. are explored both in simulation and prototype probe experimental use. In setups, 124...
In this paper, initial 3D ultrasound measurements from a 1024 channel system are presented. Measurements of Synthetic aperture imaging (SAI) and Explososcan presented compared. is the 'gold standard' for real-time medical imaging. SAI compared to by using tissue wire phantom measurements. The carried out element 2D transducer experimental scanner SARUS. To make fair comparison, two techniques use same number active channels, emissions per frame, they emit amount energy frame. were performed...
Explososcan is the 'gold standard' for real-time 3D medical ultrasound imaging. In this paper, synthetic aperture imaging compared to by simulation of point spread functions. The simulations mimic a 32×32 element prototype transducer. transducer mimicked dense matrix phased array with pitch 300 μm, made Vermon. For both techniques, 289 emissions are used image volume spanning 60° in azimuth and elevation direction 150mm depth. This results techniques frame rate 18 Hz. implemented technique...
Focused ultrasound treats tissue deep in the body without damaging surrounding structures. Driven by large-amplitude RF electrical signals, ultrasonic transducers can generate large pressure acoustic wave. Wide-bandgap semiconductors, e.g., Gallium Nitride (GaN), greatly simplify design and reduce requisite size weight of amplifiers, so improves portability focused device. Here, we demonstrate a compact 8-phase 5 MHz Class-D resonant amplifier for cancer therapy application.
We developed previously a 2D CMUT array with capability to both do imaging and generate HIFU for ablation of targeted tissues without collateral damage. This new technology allows more compact system, when compared conventional systems composed transducers made PZT, cooling PZT additional guidance systems. In this paper we present dc RF power electronics that drive our array. The are significantly capable fast-switching between mode.
This paper presents 3D vector flow images obtained using the Transverse Oscillation (TO) method. The method employs a 2D transducer and estimates three velocity components simultaneously, which is important for visualizing complex patterns. Data are acquired experimental ultrasound scanner SARUS on flow-rig system with steady flow. vessel of centered at depth 30 mm, has an expected circular-symmetric parabolic profile peak 1 m/s. Ten frames in cross-sectional plane orthogonal to center axis...
This paper presents a new beamforming method for real-time three-dimensional (3-D) ultrasound imaging using 2-D matrix transducer. To obtain images with sufficient resolution and contrast, several thousand elements are needed. The proposed reduces the required channel count from transducer to main system, by including electronics in handle. reduction of element is achieved sequential scheme. scheme combination fixed focus beamformer second dynamic system. capability synthetic aperture...