Development of a Compact Photoacoustic Tomography Imaging System with Dual Single-Element Transducers for Image Enhancement

Abstract Objective This paper proposes a new photoacoustic computed tomography (PACT) imaging system employing dual ultrasonic transducers with different frequencies. When imaging complex biological tissues, photoacoustic (PA) signals with multiple frequencies are produced simultaneously; however, due to the limited bandwidth of a single-frequency transducer, the received PA signals with specific frequencies may be missing, leading to a low imaging quality. Methods In contrast to our previous work, the proposed system has a compact volume as well as specific selection of the detection center frequency of the transducer, which can provide a comprehensive range for the detection of PA signals. In this study, a series of numerical simulation and phantom experiments were performed to validate the efficacy of the developed PACT system. Results The images generated by our system combined the advantages of both high resolution and ideal brightness/contrast. Conclusion The interchangeability of transducers with different frequencies provides potential for clinical deployment under the circumstance where a single frequency transducer cannot perform well.

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Development of a Stationary 3D Photoacoustic Imaging System Using Sparse Single-Element Transducers: Phantom Study

Applied Sciences ◽

10.3390/app9214505 ◽

2019 ◽

Vol 9 (21) ◽

pp. 4505 ◽

Cited By ~ 1

Author(s):

Karl Kratkiewicz ◽

Rayyan Manwar ◽

Mohsin Zafar ◽

Seyed Mohsen Ranjbaran ◽

Moein Mozaffarzadeh ◽

...

Keyword(s):

Breast Imaging ◽

Imaging System ◽

Photoacoustic Imaging ◽

Copper Wire ◽

Reconstruction Algorithm ◽

Biological Tissues ◽

Single Element ◽

Light Illumination ◽

Label Free ◽

Wide Range

Photoacoustic imaging (PAI) is an emerging label-free and non-invasive modality for imaging biological tissues. PAI has been implemented in different configurations, one of which is photoacoustic computed tomography (PACT) with a potential wide range of applications, including brain and breast imaging. Hemispherical Array PACT (HA-PACT) is a variation of PACT that has solved the limited detection-view problem. Here, we designed an HA-PACT system consisting of 50 single element transducers. For implementation, we initially performed a simulation study, with parameters close to those in practice, to determine the relationship between the number of transducers and the quality of the reconstructed image. We then used the greatest number of transducers possible on the hemisphere and imaged copper wire phantoms coated with a light absorbing material to evaluate the performance of the system. Several practical issues such as light illumination, arrangement of the transducers, and an image reconstruction algorithm have been comprehensively studied.

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Encapsulation of Capacitive Micromachined Ultrasonic Transducers (CMUTs) for the Acoustic Communication between Medical Implants

Sensors ◽

10.3390/s21020421 ◽

2021 ◽

Vol 21 (2) ◽

pp. 421

Author(s):

Jorge Oevermann ◽

Peter Weber ◽

Steffen H. Tretbar

Keyword(s):

Data Security ◽

Ultrasonic Transducers ◽

Surrounding Tissue ◽

Center Frequency ◽

Medical Implants ◽

Research Groups ◽

Capacitive Micromachined Ultrasonic Transducers ◽

Polyether Ether Ketone ◽

High Bandwidth ◽

Ether Ketone

The aim of this work was to extend conventional medical implants by the possibility of communication between them. For reasons of data security and transmitting distances, this communication should be realized using ultrasound, which is generated and detected by capacitive micromachined ultrasonic transducers (CMUTs). These offer the advantage of an inherent high bandwidth and a high integration capability. To protect the surrounding tissue, it has to be encapsulated. In contrast to previous results of other research groups dealing with the encapsulation of CMUTs, the goal here is to integrate the CMUT into the housing of a medical implant. In this work, CMUTs were designed and fabricated for a center frequency of 2 MHz in water and experimentally tested on their characteristics for operation behind layers of Polyether ether ketone (PEEK) and titanium, two typical materials for the housings of medical implants. It could be shown that with silicone as a coupling layer it is possible to operate a CMUT behind the housing of an implant. Although it changes the characteristics of the CMUT, the setup is found to be well suited for communication between two transducers over a distance of at least 8 cm.

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Single-element Ultrasound Imaging System based on Mirror Scanning

2020 IEEE International Ultrasonics Symposium (IUS) ◽

10.1109/ius46767.2020.9251380 ◽

2020 ◽

Author(s):

Seongwook Choi ◽

Jin Young Kim ◽

Hae Gyun Lim ◽

Jin Woo Baik ◽

Hyung Ham Kim ◽

...

Keyword(s):

Ultrasound Imaging ◽

Imaging System ◽

Single Element

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Synthetic Aperture Imaging Using High-Frequency Convex Array for Ophthalmic Ultrasound Applications

Sensors ◽

10.3390/s21072275 ◽

2021 ◽

Vol 21 (7) ◽

pp. 2275

Author(s):

Hae Gyun Lim ◽

Hyung Ham Kim ◽

Changhan Yoon

Keyword(s):

Image Quality ◽

Penetration Depth ◽

Spatial Resolution ◽

High Frequency ◽

Imaging System ◽

Ex Vivo ◽

Synthetic Aperture ◽

Single Element ◽

High Frequency Ultrasound ◽

Synthetic Aperture Imaging

High-frequency ultrasound (HFUS) imaging has emerged as an essential tool for pre-clinical studies and clinical applications such as ophthalmic and dermatologic imaging. HFUS imaging systems based on array transducers capable of dynamic receive focusing have considerably improved the image quality in terms of spatial resolution and signal-to-noise ratio (SNR) compared to those by the single-element transducer-based one. However, the array system still suffers from low spatial resolution and SNR in out-of-focus regions, resulting in a blurred image and a limited penetration depth. In this paper, we present synthetic aperture imaging with a virtual source (SA-VS) for an ophthalmic application using a high-frequency convex array transducer. The performances of the SA-VS were evaluated with phantom and ex vivo experiments in comparison with the conventional dynamic receive focusing method. Pre-beamformed radio-frequency (RF) data from phantoms and excised bovine eye were acquired using a custom-built 64-channel imaging system. In the phantom experiments, the SA-VS method showed improved lateral resolution (>10%) and sidelobe level (>4.4 dB) compared to those by the conventional method. The SNR was also improved, resulting in an increased penetration depth: 16 mm and 23 mm for the conventional and SA-VS methods, respectively. Ex vivo images with the SA-VS showed improved image quality at the entire depth and visualized structures that were obscured by noise in conventional imaging.

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DDEL-13. FOCUSED ULTRASOUND MEDIATED BLOOD BRAIN BARRIER DISRUPTION IN A MURINE MODEL OF PONTINE GLIOMA: A SAFETY AND FEASIBILITY STUDY

Neuro-Oncology ◽

10.1093/neuonc/noaa222.048 ◽

2020 ◽

Vol 22 (Supplement_3) ◽

pp. iii286-iii286

Author(s):

Zachary Englander ◽

Hong-Jian Wei ◽

Antonios Pouliopoulos ◽

Pavan Upadhyayula ◽

Chia-Ing Jan ◽

...

Keyword(s):

Blood Brain Barrier ◽

Focused Ultrasound ◽

Brain Barrier ◽

Center Frequency ◽

Single Element ◽

Pontine Glioma ◽

Orthotopic Model ◽

Function Generator ◽

Blood Brain ◽

Glioma Model

Abstract BACKGROUND Drug delivery remains a major obstacle in DIPG, as the blood brain barrier (BBB) limits the penetration of systemic therapies to the brainstem. Focused ultrasound (FUS) is an exciting new technology that, when combined with microbubbles, can open the BBB permitting the entry of drugs across the cerebrovasculature. Given that the utility of FUS in brainstem tumors remains unknown, the purpose of our study was to determine the safety and feasibility of this technique in a murine pontine glioma model. METHODS A syngeneic orthotopic model was established by stereotactic injection of PDGF-B+PTEN-/-p53-/- murine glioma cells (10,000/1ul) into the pons of B6 albino mice. A single-element, spherical-segment FUS transducer (center frequency=1.5MHz) driven by a function generator through a power amplifier (acoustic pressure=0.7MPa) was used with concurrent intravenous microbubble injection (FUS+MB) to sonicate the tumor on post-injection day 14. BBB opening was confirmed with gadolinium-enhanced MRI and Evans blue. Kondziela inverted screen (KIS) testing was completed to measure motor function. Mice were either immediately sacrificed for histopathological assessment or serially monitored for survival. RESULTS In mice treated with FUS (n=11), there was no measured deficit in KIS testing. Additionally, the degree of intra-tumoral hemorrhage and inflammation on H&E in control (n=5) and treated mice (n=5) was similar. Lastly, there was no difference in survival between the groups (control, n=6, median=26 days; FUS, n=6, median=25 days, p>0.05). CONCLUSION FUS+MB is a safe and feasible technique to open the BBB in a preclinical pontine glioma model.

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Breast cancer margin detection with a single frequency terahertz imaging system

10.1117/12.2216385 ◽

2016 ◽

Cited By ~ 3

Author(s):

Sigfrid K. Yngvesson ◽

Andrew Karellas ◽

Stephen Glick ◽

Ashraf Khan ◽

Paul R. Siqueira ◽

...

Keyword(s):

Breast Cancer ◽

Imaging System ◽

Terahertz Imaging ◽

Single Frequency ◽

Margin Detection

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Modeling Features of a Single Phase-to-Earth Fault in a Medium Voltage Overhead Transmission Line

UKH Journal of Science and Engineering ◽

10.25079/ukhjse.v4n2y2020.pp127-138 ◽

2020 ◽

Vol 4 (2) ◽

pp. 127-138

Author(s):

Ismael Saeed ◽

Kamal Sheikhyounis

Keyword(s):

Transmission Line ◽

Transmission Lines ◽

Single Phase ◽

Single Frequency ◽

Mathematical Representation ◽

Medium Voltage ◽

Overhead Transmission Line ◽

Earth Fault ◽

Distributed Parameters ◽

Selection Of

The modeling and calculation of a single phase-to-earth fault of 6 to 35 kV have specific features when compared with circuits with higher nominal voltages. In this paper, a mathematical analysis and modeling of a 3-phase overhead transmission line with distributed parameters consisting of several nominal T-shaped, 3-phase links with concentrated parameters replaced by 1 nominal T-shaped link were carried out. Further analysis showed that not accounting for the distributed nature of the line parameters did not cause significant errors in the assessment of the maximum overvoltage in the arc suppression in single phase-to-earth faults, and that sufficient accuracy insures the representation of the line by only 1 nominal T-shaped, 3-phase link. Such a modeling technique makes it impossible to identify the location of single-phase faults, which is the property of higher harmonic amplification of individual frequencies. Chain equivalent schemas with constant parameters are valid for a single frequency, thereby providing an opportunity to study the nature of the wave process by the discrete selection of parameters. Next in the mathematical representation, we consider the overhead transmission lines as lines with distributed parameters.

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Fabrication of high frequency (25-75 MHz) single element ultrasonic transducers

1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027) ◽

10.1109/ultsym.1999.849191 ◽

2003 ◽

Cited By ~ 3

Author(s):

J.M. Cannata ◽

J.-Z. Zhao ◽

S. Ayyappan ◽

T.A. Ritter ◽

W. Chen ◽

...

Keyword(s):

High Frequency ◽

Ultrasonic Transducers ◽

Single Element

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Determination of the Ultrasonic Velocity on a Recent and Aged Pine Wood

10.1115/qnde2021-74998 ◽

2021 ◽

Author(s):

Héctor Carreon ◽

Mayra Carrillo

Keyword(s):

Ultrasonic Velocity ◽

Research Work ◽

Physical And Mechanical Properties ◽

Degradation Process ◽

Ultrasonic Transducers ◽

Center Frequency ◽

Ultrasonic Emission ◽

Significant Mass

Abstract Aging in wood is the inevitable modification of physical and mechanical properties due to deterioration caused by different factors such as organisms that destroy wood, photodegradation, weathering or long-term loading. During the wood degradation process, significant mass, stiffness and strength are lost. Therefore, it is relevant to monitor the wood decomposition process to guarantee the structural requirements in buildings. This research work aims to report the influence of degradation in wood due to deterioration through the use of ultrasonic measurements. Longitudinal and transverse ultrasonic velocities were calculated using the ultrasonic emission-transmission technique for aged and unaged Mexican pine (Pinus Strobus) wood. The experimental measurements were carried out using longitudinal and shear wave ultrasonic transducers with a center frequency of 1.0 MHz and 0.5MHz respectively. Scanning electron microscopy (SEM) was performed to establish a direct correlation with the behavior of the ultrasonic wave developed in naturally aged and unaged wood. Measurements revealed higher ultrasonic velocity values for unaged wood samples in longitudinal, tangential and radial directions compared to aged wood samples, but no significant differences were found in all other wood directions.

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