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Kim J, Kim J, Lee DK, Shin EJ, Chang JH. High-Intensity focused ultrasound linear array and system for dermatology treatment. ULTRASONICS 2024; 145:107477. [PMID: 39332247 DOI: 10.1016/j.ultras.2024.107477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2024] [Revised: 09/15/2024] [Accepted: 09/16/2024] [Indexed: 09/29/2024]
Abstract
Dermatological lesions are typically located just a few millimeters below the surface of the skin, which constrains the efficacy of optical-based therapeutic methods such as photothermal and photodynamic therapy due to limited therapeutic depth caused by optical scattering. As an alternative, high-intensity focused ultrasound (HIFU) has been explored for its potential to treat a variety of dermatological conditions because it offers greater flexibility in terms of treatment depth. Since dermatological lesions have a small thickness ranging from 1.5 to 2.0 mm, high-frequency ultrasound (3-10 MHz or higher) is preferred as the focal area is proportional to the operating frequency. However, due to the difficulty in fabricating HIFU array transducers at this frequency range, the majority of HIFU treatments for dermatology rely on single element transducers. Despite the advantages of HIFU, single-element-based HIFU systems are limited in prevalent use for dermatology treatment due to their fixed focal length and mechanical movement for treatment, which can be time-consuming and unsuitable for treating multiple lesions. To address this, we present a newly developed HIFU linear array and 128-channel driving electronics specifically designed for dermatology treatment. This array consists of 128 elements, has a center frequency of 3.7 MHz, an elevation focal length of 28 mm, and an F-number of 1.27 in the elevation direction. The array has a footprint of 71.6 mm by 22 mm. Experiments using a tissue-mimicking phantom have demonstrated that the HIFU linear array and system are capable of transmitting sufficient ultrasound energy to create coagulation inside the phantom.
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Affiliation(s)
- Juhwan Kim
- Department of Electrical Engineering and Computer Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea
| | - Jinwoo Kim
- Department of Electrical Engineering and Computer Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea
| | - Duk Kyu Lee
- The Ceramic Business Unit, Dong Il Technology, Ltd., Gyeonggi-do, Korea
| | - Eui-Ji Shin
- Department of Electronic Engineering, Sogang University, Seoul, Korea
| | - Jin Ho Chang
- Department of Electrical Engineering and Computer Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea.
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2
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Hsieh ZH, Fan CH, Lin YC, Yeh CK. Electrowetting-driven liquid lens for ultrasound: Enabling controllable focal length and flexible beam steering. ULTRASONICS 2023; 135:107147. [PMID: 37651840 DOI: 10.1016/j.ultras.2023.107147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 06/08/2023] [Accepted: 08/25/2023] [Indexed: 09/02/2023]
Abstract
Focused ultrasound is an increasingly popular non-invasive treatment modality. Still, its fixed focal point requires an array ultrasound transducer or scanning system to cover different therapeutic scenarios. To address this limitation, we developed an electrically-controlled liquid lens that enables dynamic beam focusing and steering of the incident plane ultrasound beam. The lens was carefully optimized for low-energy attenuation and low-voltage driving. We evaluated the performance of the lens using a homemade 5.5-MHz planar transducer with a 7.5-mm aperture. Our results demonstrate that the planar ultrasound beam can be adjusted to a focused beam with a focal length from 27 mm to 32 mm within 1 s by increasing the electric input (0-60 V) to the lens. Additionally, the beam angle of the ultrasound is tunable from -5 to 5° by adjusting the charge distribution on the lens. Our design enables real-time, fast-response, on-demand changing of focal length and beam angle for a single-element planar transducer. Our study presents a promising technology for altering the ultrasound beam of a planar single-element transducer for different ultrasound applications. The development of this electrically-controlled liquid lens has the potential to enhance the efficacy of focused ultrasound treatment and improve patient outcomes.
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Affiliation(s)
- Zong-Han Hsieh
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Ching-Hsiang Fan
- Department of Biomedical Engineering, National Cheng Kung University, Tainan 70101, Taiwan; Medical Device Innovation Center, National Cheng Kung University, Tainan 70101, Taiwan
| | - Yeu-Chern Lin
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Chih-Kuang Yeh
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan.
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3
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Duncan B, Al-Kassas R, Zhang G, Hughes D, Qiu Y. Ultrasound-Mediated Ocular Drug Delivery: From Physics and Instrumentation to Future Directions. MICROMACHINES 2023; 14:1575. [PMID: 37630111 PMCID: PMC10456754 DOI: 10.3390/mi14081575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/27/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023]
Abstract
Drug delivery to the anterior and posterior segments of the eye is impeded by anatomical and physiological barriers. Increasingly, the bioeffects produced by ultrasound are being proven effective for mitigating the impact of these barriers on ocular drug delivery, though there does not appear to be a consensus on the most appropriate system configuration and operating parameters for this application. In this review, the fundamental aspects of ultrasound physics most pertinent to drug delivery are presented; the primary phenomena responsible for increased drug delivery efficacy under ultrasound sonication are discussed; an overview of common ocular drug administration routes and the associated ocular barriers is also given before reviewing the current state of the art of ultrasound-mediated ocular drug delivery and its potential future directions.
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Affiliation(s)
- Blair Duncan
- School of Engineering, Faculty of Engineering & Technology, Liverpool John Moores University, James Parsons Building, Byrom Street, Liverpool L3 3AF, UK
| | - Raida Al-Kassas
- School of Pharmacy & Biomolecular Sciences, Faculty of Science, Liverpool John Moores University, James Parsons Building, Byrom Street, Liverpool L3 3AF, UK
| | - Guangming Zhang
- School of Engineering, Faculty of Engineering & Technology, Liverpool John Moores University, James Parsons Building, Byrom Street, Liverpool L3 3AF, UK
| | - Dave Hughes
- Novosound Ltd., Biocity, BoNess Road, Newhouse, Glasgow ML1 5UH, UK
| | - Yongqiang Qiu
- School of Engineering, Faculty of Engineering & Technology, Liverpool John Moores University, James Parsons Building, Byrom Street, Liverpool L3 3AF, UK
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Mekonnen T, Schill AW, Zevallos-Delgado C, Singh M, Aglyamov SR, Larin KV. Reverberant optical coherence elastography using multifocal acoustic radiation force. OPTICS LETTERS 2023; 48:2773-2776. [PMID: 37262207 DOI: 10.1364/ol.482201] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 04/15/2023] [Indexed: 06/03/2023]
Abstract
In this study, we introduce a multifocal acoustic radiation force source that combines an ultrasound transducer and a 3D-printed acoustic lens for application in reverberant optical coherence elastography (Rev-OCE). An array of plano-concave acoustic lenses, each with an 11.8 mm aperture diameter, were used to spatially distribute the acoustic energy generated by a 1 MHz planar ultrasound transducer, producing multiple focal spots on a target plane. These focal spots generate reverberant shear wave fields detected by the optical coherence tomography (OCT) system. The effectiveness of the multifocal Rev-OCE system in probing mechanical properties with high resolution is demonstrated in layered gelatin phantoms.
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Sun Y, Tao J, Guo F, Wang F, Dong J, Jin L, Li S, Huang X. AZ31B magnesium alloy matching layer for Lens-focused piezoelectric transducer application. ULTRASONICS 2023; 127:106844. [PMID: 36095851 DOI: 10.1016/j.ultras.2022.106844] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 08/14/2022] [Accepted: 09/01/2022] [Indexed: 06/15/2023]
Abstract
Compared with planar transducers, focused transducers have higher ultrasound intensity and better lateral resolution in the focal zone. At present, the matching layer materials for focused transducers are mainly 0-3 composite materials, which have problems such as non-uniformity, difficulty to fabricate at high frequencies, and large sound attenuation. In this paper, finite element analysis is carried out to simulate lens-focused transducers with different matching layer structures and materials. It is found that the focused transducer with magnesium alloy matching layer has the best comprehensive performance. A lens-focused PZT-5H ultrasonic transducer was then fabricated with AZ31B magnesium alloy as the first matching layer. The measured results show that the center frequency of the transducer is 4.38 MHz, the -6-dB bandwidth is 68.35 % and the insertion loss is -13.88 dB. Benefiting from the high uniformity, high acoustic impedance and extremely low acoustic attenuation of magnesium alloy, the transducers in this research exhibit superior performances than other reported transducers with conventional matching layer. The current work suggests that AZ31B magnesium alloy is a promising matching layer material for ultrasonic transducers.
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Affiliation(s)
- Yuhou Sun
- National Engineering Research Center of Light Alloy Net Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Jingya Tao
- National Engineering Research Center of Light Alloy Net Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Feifei Guo
- School of Materials Science and Chemical Engineering, Xi'an Technological University, Xi'an, China
| | - Fulin Wang
- National Engineering Research Center of Light Alloy Net Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China.
| | - Jie Dong
- National Engineering Research Center of Light Alloy Net Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Li Jin
- National Engineering Research Center of Light Alloy Net Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Shiyang Li
- Department of Instrument Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Xingyi Huang
- Shanghai Key Lab of Electrical Insulation and Thermal Aging, Shanghai Jiao Tong University, Shanghai, China
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Chen H, Agrawal S, Osman M, Minotto J, Mirg S, Liu J, Dangi A, Tran Q, Jackson T, Kothapalli SR. A Transparent Ultrasound Array for Real-Time Optical, Ultrasound, and Photoacoustic Imaging. BME FRONTIERS 2022; 2022:9871098. [PMID: 37850172 PMCID: PMC10521654 DOI: 10.34133/2022/9871098] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 04/28/2022] [Indexed: 10/19/2023] Open
Abstract
Objective and Impact Statement. Simultaneous imaging of ultrasound and optical contrasts can help map structural, functional, and molecular biomarkers inside living subjects with high spatial resolution. There is a need to develop a platform to facilitate this multimodal imaging capability to improve diagnostic sensitivity and specificity. Introduction. Currently, combining ultrasound, photoacoustic, and optical imaging modalities is challenging because conventional ultrasound transducer arrays are optically opaque. As a result, complex geometries are used to coalign both optical and ultrasound waves in the same field of view. Methods. One elegant solution is to make the ultrasound transducer transparent to light. Here, we demonstrate a novel transparent ultrasound transducer (TUT) linear array fabricated using a transparent lithium niobate piezoelectric material for real-time multimodal imaging. Results. The TUT-array consists of 64 elements and centered at ~6 MHz frequency. We demonstrate a quad-mode ultrasound, Doppler ultrasound, photoacoustic, and fluorescence imaging in real-time using the TUT-array directly coupled to the tissue mimicking phantoms. Conclusion. The TUT-array successfully showed a multimodal imaging capability and has potential applications in diagnosing cancer, neurological, and vascular diseases, including image-guided endoscopy and wearable imaging.
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Affiliation(s)
- Haoyang Chen
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Sumit Agrawal
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Mohamed Osman
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Josiah Minotto
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Shubham Mirg
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Jinyun Liu
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Ajay Dangi
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Quyen Tran
- School of Electrical Engineering and Computer Science, The Pennsylvania State University, University Park, PA 16802, USA
| | - Thomas Jackson
- School of Electrical Engineering and Computer Science, The Pennsylvania State University, University Park, PA 16802, USA
| | - Sri-Rajasekhar Kothapalli
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
- Penn State Cancer Institute, The Pennsylvania State University, Hershey, PA 17033, USA
- Graduate Program in Acoustics, The Pennsylvania State University, University Park, PA 16802, USA
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7
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Chen K, Irie T, Iijima T, Morita T. Wideband Multimode Excitation by a Double-Parabolic-Reflector Ultrasonic Transducer. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2020; 67:1620-1631. [PMID: 32149685 DOI: 10.1109/tuffc.2020.2978234] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This research presents double-parabolic-reflector wave-guided ultrasonic transducers in order to realize wideband (0-2.5 MHz), multiharmonic mode excitations (over 20 modes), and to obtain large mechanical/acoustic outputs. The double-parabolic-reflector mechanism serves as a horn structure at low frequencies and acoustic-focusing structure at high frequencies to enhance the energy density of the incident ultrasound. Upon combining simulation and experimental methods, we examined and verified the basic performance and working mechanisms of the double-parabolic-reflector waveguides: multimode excitation belongs to the harmonic modes from the thin waveguide. At the megahertz range near the thickness mode of the piezoelectric element (PZT), energy density of the incident ultrasound is enhanced by double-parabolic reflections, and the amplification ranges 10 to 40× between 1 and 2.5 MHz. At burst excitations, the amplification performance is independent of the length of the thin waveguide. Compared with conventional Langevin transducers and high-intensity focused ultrasound (HIFU) transducers, our transducers possess a wide working frequency with large mechanical/acoustic outputs and large vibration velocity amplification. By introducing these new features, our proposed method is a promising candidate for examining basic physics parameters, such as frequency dependence, in the fields of medicine, biology, industry, etc.
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Abstract
Abstract
Purpose
Photoacoustic (PA) microscopy has emerged as a useful tool in biomedical imaging applications such as visualization of microvasculature and hemoglobin oxygen saturation, single-cell, and label-free imaging of organs including cancer. Since the ultrasound transducers used for PA signal detection are not optically transparent, the integration of optical and acoustic modules for coaxial alignment of laser and acoustic beam fields in PA microscopy is complex and costly.
Methods
Here, we report a recently developed optically transparent focused transducer for combined PA and ultrasound (US) microscopy. All the acoustic layers including the acoustic lens are optically transparent, enabling simple integration of optical and acoustic modules for both imaging modalities.
Results
The mean light transmittance of the transducer’s backing layer and acoustic lens and of the transducer itself were measured at 92%, 83%, and 66%, respectively. Results from in vitro and in vivo experiments demonstrated the transducer to be suitable for both US and PA imaging.
Conclusions
The results of this study represent a step toward efficient construction of probes for combined PA and US microscopy.
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9
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Leartprapun N, Iyer RR, Mackey CD, Adie SG. Spatial localization of mechanical excitation affects spatial resolution, contrast, and contrast-to-noise ratio in acoustic radiation force optical coherence elastography. BIOMEDICAL OPTICS EXPRESS 2019; 10:5877-5904. [PMID: 31799053 PMCID: PMC6865116 DOI: 10.1364/boe.10.005877] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 09/30/2019] [Accepted: 10/06/2019] [Indexed: 05/05/2023]
Abstract
The notion that a spatially confined mechanical excitation would produce an elastogram with high spatial resolution has motivated the development of various elastography techniques with localized mechanical excitation. However, a quantitative investigation of the effects of spatial localization of mechanical excitation on the spatial resolution of elastograms is still lacking in optical coherence elastography (OCE). Here, we experimentally investigated the effect of spatial localization of acoustic radiation force (ARF) excitation on spatial resolution, contrast, and contrast-to-noise ratio (CNR) of dynamic uniaxial strain elastograms in dynamic ARF-OCE, based on a framework for analyzing the factors that influence the quality of the elastogram at different stages of the elastography workflow. Our results show that localized ARF excitation with a smaller acoustic focal spot size produced a strain elastogram with superior spatial resolution, contrast, and CNR. Our results also suggest that the spatial extent spanned by the displacement response in the sample may connect between the spatial localization of the mechanical excitation and the resulting elastogram quality. The elastography framework and experimental approach presented here may provide a basis for the quantitative analysis of elastogram quality in OCE that can be adapted and applied to different OCE systems and applications.
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Affiliation(s)
- Nichaluk Leartprapun
- Cornell University, Meinig School of Biomedical Engineering, Weill Hall, Ithaca, New York 14853, USA
| | - Rishyashring R. Iyer
- Cornell University, Meinig School of Biomedical Engineering, Weill Hall, Ithaca, New York 14853, USA
- Present address: University of Illinois at Urbana-Champaign, Beckman Institute for Advanced Science and Technology, Urbana, Illinois 61801, USA
| | - Colin D. Mackey
- Cornell University, Meinig School of Biomedical Engineering, Weill Hall, Ithaca, New York 14853, USA
| | - Steven G. Adie
- Cornell University, Meinig School of Biomedical Engineering, Weill Hall, Ithaca, New York 14853, USA
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10
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Nguyen TP, Truong NTP, Bui NQ, Nguyen VT, Hoang G, Choi J, Phan TTV, Pham VH, Kim BG, Oh J. Design, Fabrication, and Evaluation of Multifocal Point Transducer for High-Frequency Ultrasound Applications. SENSORS (BASEL, SWITZERLAND) 2019; 19:E609. [PMID: 30717095 PMCID: PMC6386936 DOI: 10.3390/s19030609] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 01/28/2019] [Accepted: 01/29/2019] [Indexed: 12/30/2022]
Abstract
The present study illustrates the design, fabrication, and evaluation of a novel multifocal point (MFP) transducer based on polyvinylidene fluoride (PVDF) film for high-frequency ultrasound application. The fabricated MFP surface was press-focused using a computer numerical control (CNC) machining tool-customized multi-spherical pattern object. The multi-spherical pattern has five spherical surfaces with equal area and connected continuously to have the same energy level at focal points. Center points of these spheres are distributed in a linear pattern with 1 mm distance between each two points. The radius of these spheres increases steadily from 10 mm to 13.86 mm. The designed MFP transducer had a center frequency of 50 MHz and a -6 dB bandwidth of 68%. The wire phantom test was conducted to study and demonstrate the advantages of this novel design. The obtained results for MFP transducer revealed a significant increase (4.3 mm) of total focal zone in the near-field and far-field area compared with 0.48 mm obtained using the conventional single focal point transducer. Hence, the proposed method is promising to fabricate MFP transducers for deeper imaging depth applications.
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Affiliation(s)
- Thanh Phuoc Nguyen
- Interdisciplinary Program of Biomedical Mechanical and Electrical Engineering, Pukyong National University, Busan 48513, Korea.
- Center for Marine-Integrated Biomedical Technology, Pukyong National University, Busan 48513, Korea.
| | - Nguyen Thanh Phong Truong
- Interdisciplinary Program of Biomedical Mechanical and Electrical Engineering, Pukyong National University, Busan 48513, Korea.
| | - Nhat Quang Bui
- Center for Marine-Integrated Biomedical Technology, Pukyong National University, Busan 48513, Korea.
| | - Van Tu Nguyen
- Interdisciplinary Program of Biomedical Mechanical and Electrical Engineering, Pukyong National University, Busan 48513, Korea.
| | - Giang Hoang
- Center for Marine-Integrated Biomedical Technology, Pukyong National University, Busan 48513, Korea.
| | - Jaeyeop Choi
- Interdisciplinary Program of Biomedical Mechanical and Electrical Engineering, Pukyong National University, Busan 48513, Korea.
| | - Thi Tuong Vy Phan
- Interdisciplinary Program of Biomedical Mechanical and Electrical Engineering, Pukyong National University, Busan 48513, Korea.
- Center for Marine-Integrated Biomedical Technology, Pukyong National University, Busan 48513, Korea.
| | - Van Hiep Pham
- Interdisciplinary Program of Biomedical Mechanical and Electrical Engineering, Pukyong National University, Busan 48513, Korea.
| | - Byung-Gak Kim
- College of Future Convergence, Pukyong National University, Busan 48513, Korea.
| | - Junghwan Oh
- Interdisciplinary Program of Biomedical Mechanical and Electrical Engineering, Pukyong National University, Busan 48513, Korea.
- Center for Marine-Integrated Biomedical Technology, Pukyong National University, Busan 48513, Korea.
- Department of Biomedical Engineering, Pukyong National University, Busan 48513, Korea.
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Tarrazó-Serrano D, Castiñeira-Ibáñez S, Minin OV, Candelas P, Rubio C, Minin IV. Design of Acoustical Bessel-Like Beam Formation by a Pupil Masked Soret Zone Plate Lens. SENSORS 2019; 19:s19020378. [PMID: 30658500 PMCID: PMC6359387 DOI: 10.3390/s19020378] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 01/08/2019] [Accepted: 01/15/2019] [Indexed: 11/16/2022]
Abstract
The image performance of acoustic and ultrasound sensors depends on several fundamental parameters such as depth of focus or lateral resolution. There are currently two different types of acoustic diffractive lenses: those that form a diffraction-limited spot with a shallow depth of focus (zone plates) and lenses that form an extended focus (quasi-Bessel beams). In this paper, we investigate a pupil-masked Soret zone plate, which allows the tunability of a normalized angular spectrum. It is shown that the depth of focus and the lateral resolution can be modified, without changing the lens structure, by choosing the size of the pupil mask. This effect is based on the transformation of spherically-converging waves into quasi-conical waves, due to the apodization of the central part of the zone plate. The theoretical analysis is verified with both numerical simulations and experimental measurements. A Soret zone plate immersed in water with D/2F = 2.5 and F = 4.5λ changes its depth of focus from 2.84λ to 5.9λ and the lateral resolution increases from 0.81λ to 0.64λ at a frequency of 250 kHz, by modifying the pupil mask dimensions of the Soret zone plate.
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Affiliation(s)
- Daniel Tarrazó-Serrano
- Centro de Tecnologías Físicas, Universitat Politècnica de València, Camí de Vera s/n, 46022 València, Spain.
| | - Sergio Castiñeira-Ibáñez
- Centro de Tecnologías Físicas, Universitat Politècnica de València, Camí de Vera s/n, 46022 València, Spain.
| | - Oleg V Minin
- Radiophysical department, Tomsk State University, 30 Lenin Avenue, Tomsk 634050, Russia.
- Engineering school of nondestructive testing, Tomsk Polytechnic University, 36 Lenin Avenue, Tomsk 634050, Russia.
| | - Pilar Candelas
- Centro de Tecnologías Físicas, Universitat Politècnica de València, Camí de Vera s/n, 46022 València, Spain.
| | - Constanza Rubio
- Centro de Tecnologías Físicas, Universitat Politècnica de València, Camí de Vera s/n, 46022 València, Spain.
| | - Igor V Minin
- Engineering school of nondestructive testing, Tomsk Polytechnic University, 36 Lenin Avenue, Tomsk 634050, Russia.
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12
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A 40-MHz Ultrasound Transducer with an Angled Aperture for Guiding Percutaneous Revascularization of Chronic Total Occlusion: A Feasibility Study. SENSORS 2018; 18:s18114079. [PMID: 30469448 PMCID: PMC6263984 DOI: 10.3390/s18114079] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 11/13/2018] [Accepted: 11/18/2018] [Indexed: 12/13/2022]
Abstract
Complete blockage of a coronary artery, called chronic total occlusion (CTO), frequently occurs due to atherosclerosis. To reopen the obstructed blood vessels with a stent, guidewire crossing is performed with the help of angiography that can provide the location of CTO lesions and the image of guidewire tip. Since angiography is incapable of imaging inside a CTO lesion, the surgeons are blind during guidewire crossing. For this reason, the success rate of guidewire crossing relies upon the proficiency of the surgeon, which is considerably reduced from 69.0% to 32.5% if extensive calcification, not penetrated by a guidewire, exists in CTO lesions. In this paper, a recently developed 40-MHz forward-looking intravascular ultrasound (FL–IVUS) transducer to visualize calcification within CTO lesions is reported. This transducer consists of a single element angled aperture and a guidewire passage. The aperture is spherically deformed to have a focal length of 3 mm in order to improve spatial resolution of FL–IVUS images. The angle between the beam direction and the axis of rotation is designed to be 30° to effectively visualize calcification within a CTO lesion as well as the blood vessel wall. The experimental results demonstrated that the developed FL–IVUS transducer facilitates visualization of calcification within CTO lesions and makes it possible to help the surgeon make decisions about whether to push the guidewire in order to cross the lesion or to change the surgical procedure.
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13
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Real-Time HIFU Treatment Monitoring Using Pulse Inversion Ultrasonic Imaging. APPLIED SCIENCES-BASEL 2018. [DOI: 10.3390/app8112219] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Real-time monitoring of high-intensity focused ultrasound (HIFU) surgery is essential for safe and accurate treatment. However, ultrasound imaging is difficult to use for treatment monitoring during HIFU surgery because of the high intensity of the HIFU echoes that are received by an imaging transducer. Here, we propose a real-time HIFU treatment monitoring method based on pulse inversion of imaging ultrasound; an imaging transducer fires ultrasound twice in 0° and 180° phases for one scanline while HIFUs of the same phase are transmitted in synchronization with the ultrasound transmission for imaging. By doing so, HIFU interferences can be eliminated after subtracting the two sets of the signals received by the imaging transducer. This function was implemented in a commercial research ultrasound scanner, and its performance was evaluated using the excised bovine liver. The experimental results demonstrated that the proposed method allowed ultrasound images to clearly show the echogenicity change induced by HIFU in the excised bovine liver. Additionally, it was confirmed that the moving velocity of the organs in the abdomen due to respiration does not affect the performance of the proposed method. Based on the experimental results, we believe that the proposed method can be used for real-time HIFU surgery monitoring that is a pivotal function for maximized treatment efficacy.
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Jang J, Chang JH. Design and Fabrication of a Miniaturized Convex Array for Combined Ultrasound and Photoacoustic Imaging of the Prostate. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2018; 65:2086-2096. [PMID: 30106721 DOI: 10.1109/tuffc.2018.2864664] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Although transrectal ultrasound (TRUS) imaging is widely used for screening and diagnosing prostate cancer, it is often not found on TRUS images, depending on its stage, size, and location. In addition, due to the weak echo signal and the low contrast of TRUS images, it is difficult to diagnose early-stage prostate cancers and distinguish malignant tumors from benign prostatic hyperplasia. For this reason, TRUS image-guided biopsy is mandatory to confirm the malignancy of the suspicious tumor, but the diagnostic accuracy of initial biopsy is only 20%-30%, so that the patients inevitably undergo repeated biopsies. TRUS-photoacoustic (TRUS-PA) imaging is one way to resolve those problems. However, the development of a TRUS-PA probe, in which an ultrasound array transducer and optical fibers are integrated, is demanding because the overall size of the probe should be as small as possible for the convenience of the patients, while providing the desired performances. Here, we report a recently developed TRUS-PA probe. The core element of the TRUS-PA is a miniaturized 128-element, 7-MHz convex array transducer of which size in the lateral and elevational directions is 11.4 and 5 mm, respectively. A new concept of a flexible printed circuit board was also developed to limit the size of the TRUS-PA probe to less than 15 mm. From the performance evaluation, it was found that the developed array with a field-of-view of 134° has a center frequency of 6.75 MHz, a -6-dB fractional bandwidth of 66%, and a crosstalk of less than -45 dB. In the tissue-mimicking phantom test and ex vivo experiments, the miniaturized convex array proved to be capable of providing combined US and PA images with acceptable imaging quality in spite of its small size.
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Kim H, Jo G, Chang JH. Ultrasound-assisted photothermal therapy and real-time treatment monitoring. BIOMEDICAL OPTICS EXPRESS 2018; 9:4472-4480. [PMID: 30615724 PMCID: PMC6157783 DOI: 10.1364/boe.9.004472] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/25/2018] [Accepted: 08/20/2018] [Indexed: 06/09/2023]
Abstract
Photothermal therapy (PTT) has the capability for selective treatment, in which light delivered to the target is converted into heat and subsequently causes coagulative necrosis. However, optical scattering in biological media limits light penetration, thus reducing therapeutic efficacy. Here, we demonstrate that the temperatures generated by light and ultrasound energies can be added constructively in resected melanoma cancers, which causes an increase in treatment depth. This method is called dual thermal therapy (DTT). It is also shown that combined ultrasound and photoacoustic images acquired using the pulse sequence proposed in this paper can be used for real-time monitoring of DTT.
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Affiliation(s)
- Haemin Kim
- Department of Biomedical Engineering, Sogang University, Seoul, 04107, South Korea
| | - Gyuwon Jo
- Department of Electronic Engineering, Sogang University, Seoul, 04107, South Korea
| | - Jin Ho Chang
- Department of Biomedical Engineering, Sogang University, Seoul, 04107, South Korea
- Department of Electronic Engineering, Sogang University, Seoul, 04107, South Korea
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Lee J, Shin EJ, Lee C, Chang JH. Development of Dual-Frequency Oblong-Shaped-Focused Transducers for Intravascular Ultrasound Tissue Harmonic Imaging. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2018; 65:1571-1582. [PMID: 29994203 DOI: 10.1109/tuffc.2018.2844869] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Tissue harmonic imaging (THI), an essential mode of commercial ultrasound imaging scanners, can provide images with high spatial and contrast resolutions. For THI, the frequency spectrum of a transducer is generally divided for the transmission of fundamental signal and the reception of its second harmonic. Therefore, it is difficult to use the THI mode for intravascular ultrasound (IVUS) imaging because typical IVUS transducers have a narrow -6-dB fractional bandwidth of about 50%. Due to its small aperture (about 0.5 mm) and the strength of IVUS being too weak, it is difficult to construct a high-quality tissue harmonic image. In this paper, we report a recently developed dual-frequency oblong-shaped-focused IVUS transducer for high-quality intravascular THI; the transducer consists of three elements arranged side by side in the horizontal (i.e., elevation) direction. The two outer elements with a center frequency of 35 MHz are responsible for ultrasound transmission and the center element has a center frequency of 70 MHz for the reception of the second-harmonic signals. All three elements have a spherical shape with a radius of 3 mm to efficiently generate harmonics in the region of interest. This configuration of the developed IVUS transducer was determined to facilitate high-quality THI, which was based on the results of Field II simulation and finite-element analysis. The images of wires and a tissue-mimicking phantom indicated that the tissue harmonic images produced by the developed transducer have not only a high spatial resolution but also a deep imaging depth, compared to the 35- and 70-MHz fundamental images.
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A 35 MHz/105 MHz Dual-Element Focused Transducer for Intravascular Ultrasound Tissue Imaging Using the Third Harmonic. SENSORS 2018; 18:s18072290. [PMID: 30011948 PMCID: PMC6069256 DOI: 10.3390/s18072290] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 07/12/2018] [Accepted: 07/13/2018] [Indexed: 12/21/2022]
Abstract
The superharmonic imaging of tissue has the potential for high spatial and contrast resolutions, compared to the fundamental and second harmonic imaging. For this technique, the spectral bandwidth of an ultrasound transducer is divided for transmission of ultrasound and reception of its superharmonics (i.e., higher than the second harmonic). Due to the spectral division for the transmission and reception, transmitted ultrasound energy is not sufficient to induce superharmonics in media without using contrast agents, and it is difficult that a transducer has a −6 dB fractional bandwidth of higher than 100%. For the superharmonic imaging of tissue, thus, multi-frequency array transducers are the best choice if available; transmit and receive elements are separate and have different center frequencies. However, the construction of a multi-frequency transducer for intravascular ultrasound (IVUS) imaging is particularly demanding because of its small size of less than 1 mm. Here, we report a recently developed dual-element focused IVUS transducer for the third harmonic imaging of tissue, which consists of a 35-MHz element for ultrasound transmission and a 105-MHz element for third harmonic reception. For high quality third harmonic imaging, both elements were fabricated to have the same focus at 2.5 mm. The results of tissue mimicking phantom tests demonstrated that the third harmonic images produced by the developed transducer had higher spatial resolution and deeper imaging depth than the fundamental images.
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Increased light penetration due to ultrasound-induced air bubbles in optical scattering media. Sci Rep 2017; 7:16105. [PMID: 29170545 PMCID: PMC5701037 DOI: 10.1038/s41598-017-16444-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 11/13/2017] [Indexed: 01/11/2023] Open
Abstract
Light is an attractive tool for high spatial- and contrast-resolution imaging, highly sensitive molecular imaging, and target-selective therapy, and it does not exhibit the risks associated with ionizing radiation. The main limitation of using light in clinical applications is its superficial imaging and therapeutic depth caused by high optical scattering in biological media. Here, we demonstrate that the scattering and thus defocusing of the incident light can be alleviated when simultaneously delivered ultrasound generates air bubbles in the pathway of the incident light, thus increasing the light penetration. The bubbles are temporally induced by ultrasound with an intensity that is sufficiently low to avoid tissue damage and act as a Mie scattering medium in which light is scattered predominantly in the forward direction. The change in the optical scattering property caused by the ultrasound is undone after cessation of the insonification. From the results, it is expected that this proposed method will open a new route for overcoming the limitations of current optical imaging and therapeutic techniques.
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