Thematische Bibliographien / Ultrasound beam mapping

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Auswahl der wissenschaftlichen Literatur zum Thema „Ultrasound beam mapping“

Autor: Grafiati

Veröffentlicht am 28. Juni 2021

Zuletzt aktualisiert am 1. Februar 2022

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Zeitschriftenartikel zum Thema "Ultrasound beam mapping"

Chen, Haoyang, Sumit Agrawal, Ajay Dangi, Christopher Wible, Mohamed Osman, Lidya Abune, Huizhen Jia, Randall Rossi, Yong Wang und Sri-Rajasekhar Kothapalli. „Optical-Resolution Photoacoustic Microscopy Using Transparent Ultrasound Transducer“. Sensors 19, Nr. 24 (11.12.2019): 5470. http://dx.doi.org/10.3390/s19245470.

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The opacity of conventional ultrasound transducers can impede the miniaturization and workflow of current photoacoustic systems. In particular, optical-resolution photoacoustic microscopy (OR-PAM) requires the coaxial alignment of optical illumination and acoustic-detection paths through complex beam combiners and a thick coupling medium. To overcome these hurdles, we developed a novel OR-PAM method on the basis of our recently reported transparent lithium niobate (LiNbO3) ultrasound transducer (Dangi et al., Optics Letters, 2019), which was centered at 13 MHz ultrasound frequency with 60% photoacoustic bandwidth. To test the feasibility of wearable OR-PAM, optical-only raster scanning of focused light through a transducer was performed while the transducer was fixed above the imaging subject. Imaging experiments on resolution targets and carbon fibers demonstrated a lateral resolution of 8.5 µm. Further, we demonstrated vasculature mapping using chicken embryos and melanoma depth profiling using tissue phantoms. In conclusion, the proposed OR-PAM system using a low-cost transparent LiNbO3 window transducer has a promising future in wearable and high-throughput imaging applications, e.g., integration with conventional optical microscopy to enable a multimodal microscopy platform capable of ultrasound stimulation.

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Acquaticci, Fabián, Sergio E. Lew und Sergio N. Gwirc. „Ultrasound Axicon: Systematic Approach to Optimize Focusing Resolution through Human Skull Bone“. Materials 12, Nr. 20 (20.10.2019): 3433. http://dx.doi.org/10.3390/ma12203433.

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The use of axicon lenses is useful in many high-resolution-focused ultrasound applications, such as mapping, detection, and have recently been extended to ultrasonic brain therapies. However, in order to achieve high spatial resolution with an axicon lens, it is necessary to adjust the separation, called stand-off (δ), between a conventional transducer and the lens attached to it. Comprehensive ultrasound simulations, using the open-source k-Wave toolbox, were performed for an axicon lens attached to a piezo-disc type transducer with a radius of 14 mm, and a frequency of about 0.5 MHz, that is within the range of optimal frequencies for transcranial transmission. The materials properties were measured, and the lens geometry was modelled. Hydrophone measurements were performed through a human skull phantom. We obtained an initial easygoing design model for the lens angle and optimal stand-off using relatively simple formulas. The skull is not an obstacle for focusing of ultrasound with optimized axicon lenses that achieve an identical resolution to spherical transducers, but with the advantage that the focusing distance is shortened. An adequate stand-off improves the lateral resolution of the acoustic beam by approximately 50%. The approach proposed provides an effective way of designing polydimethylsiloxane (PDMS)-based axicon lenses equipped transducers.

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Riemer, K., E. M. Rowland, C. H. Leow, M. X. Tang und P. D. Weinberg. „Determining Haemodynamic Wall Shear Stress in the Rabbit Aorta In Vivo Using Contrast-Enhanced Ultrasound Image Velocimetry“. Annals of Biomedical Engineering 48, Nr. 6 (04.03.2020): 1728–39. http://dx.doi.org/10.1007/s10439-020-02484-2.

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Abstract Abnormal blood flow and wall shear stress (WSS) can cause and be caused by cardiovascular disease. To date, however, no standard method has been established for mapping WSS in vivo. Here we demonstrate wide-field assessment of WSS in the rabbit abdominal aorta using contrast-enhanced ultrasound image velocimetry (UIV). Flow and WSS measurements were made independent of beam angle, curvature or branching. Measurements were validated in an in silico model of the rabbit thoracic aorta with moving walls and pulsatile flow. Mean errors over a cardiac cycle for velocity and WSS were 0.34 and 1.69%, respectively. In vivo time average WSS in a straight segment of the suprarenal aorta correlated highly with simulations (PC = 0.99) with a mean deviation of 0.29 Pa or 5.16%. To assess fundamental plausibility of the measurement, UIV WSS was compared to an analytic approximation derived from the Poiseuille equation; the discrepancy was 17%. Mapping of WSS was also demonstrated in regions of arterial branching. High time average WSS (TAWSSxz = 3.4 Pa) and oscillatory flow (OSIxz = 0.3) were observed near the origin of conduit arteries. In conclusion, we have demonstrated that contrast-enhanced UIV is capable of measuring spatiotemporal variation in flow velocity, arterial wall location and hence WSS in vivo with high accuracy over a large field of view.

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Zhang, Edward, und Paul Beard. „Broadband ultrasound field mapping system using a wavelength tuned, optically scanned focused laser beam to address a Fabry Perot polymer film sensor“. IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 53, Nr. 7 (Juli 2006): 1330–38. http://dx.doi.org/10.1109/tuffc.2006.1665081.

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Qazi, Waqas M., Olle Ekberg, Johan Wiklund, Rashid Mansoor und Mats Stading. „Simultaneous X-ray Video-Fluoroscopy and Pulsed Ultrasound Velocimetry Analyses of the Pharyngeal Phase of Swallowing of Boluses with Different Rheological Properties“. Dysphagia 35, Nr. 6 (11.02.2020): 898–906. http://dx.doi.org/10.1007/s00455-020-10092-4.

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AbstractThe Ultrasound Velocity Profiling (UVP) technique allows real-time, non-invasive flow mapping of a fluid along a 1D-measuring line. This study explores the possibility of using the UVP technique and X-ray video-fluoroscopy (XVF) to elucidate the deglutition process with the focus on bolus rheology. By positioning the UVP probe so that the pulsed ultrasonic beam passes behind the air-filled trachea, the bolus flow in the pharynx can be measured. Healthy subjects in a clinical study swallowed fluids with different rheological properties: Newtonian (constant shear viscosity and non-elastic); Boger (constant shear viscosity and elastic); and shear thinning (shear rate-dependent shear viscosity and elastic). The results from both the UVP and XVF reveal higher velocities for the shear thinning fluid, followed by the Boger and the Newtonian fluids, demonstrating that the UVP method has equivalent sensitivities for detecting the velocities of fluids with different rheological properties. The velocity of the contraction wave that clears the pharynx was measured in the UVP and found to be independent of bolus rheology. The results show that UVP not only assesses accurately the fluid velocity in a bolus flow, but it can also monitor the structural changes that take place in response to a bolus flow, with the added advantage of being a completely non-invasive technique that does not require the introduction of contrast media.

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Okihara, Koji, Kana Kobayashi, Kazumi Kamoi, Tsuyoshi Iwata und Tsuneharu Miki. „Novel dosimetric criteria for salvage permanent brachytherapy based on 3D-cancer mapping.“ Journal of Clinical Oncology 32, Nr. 4_suppl (01.02.2014): 269. http://dx.doi.org/10.1200/jco.2014.32.4_suppl.269.

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269 Background: Salvage permanent brachytherapy (SPB) is one of treatment options in recurred men after external beam radiation therapy (EBRT). The accurate 3D correspondence between recurred cancer focus and location of seed implants using transrectal sonography (TRUS) is indispensable to design excellent dosimetry. The application of MRI-TRUS fusion targeted/systematic biopsy (Fusion-B) has enabled us to draw 3D recurred-cancer mapping. We have started SPB in men who recurred 3D-conformal EBRT using 3D-cancer mapping from Fusion-B. We introduce the novel dosimetric criteria for SPB-based on 3D cancer mapping. Methods: The patients with PSA failure (defined by Pheonix criteria) and without lymphnode/distant metastasis were enrolled in this study. In men who had suspicious recurrent focus/foci in MRI, we performed Fuision-B (ultrasound equipment: Image fusion: Koelis in France, and Biopsy: Medison in South Korea). We classified the three dosimetric patterns as follows: (1) Focal pattern: one core positive from target biopsy alone within hemilobe and GS less than 8. (2) Hemi-lobe pattern: positive cores within hemi-lobe from target/ systematic biopsies and GS less than 8. (3) Whole / focused gland pattern c/w hormonal therapy: Positive core(s) with GS greater than seven was identified regardless of positive biopsies location, or positive cores with GS less than eight from bilateral lobes. Prescribed dose to the target lesion, rV100 and uD90 were planned greater than 160Gy, 0% and less than 165Gy respectively. Results: Since August 2012, SPB has underwent in nine cases (PSA range prior to SPB: 2.22- 4.97ng/ml, age 61 to 77). In those cases, prescription dose at the 3D-conformal EBRT was 72 Gy and the duration between the 3D-conformal EBRT and SPB ranged from 41 to 107 months. The biopsy GS (-7/8-) obtained from Fuison-B distributed in 6/3 cases. Biopsy revealed single focus obtained from target biopsy in two cases. Focal and hemi-lobe pattern were chosen in two and one case, respectively. For the present, there is no re-PSA failure and G3-4 GI and GU comorbidities. Conclusions: To reduce the incidence of co-morbidity and maintain reasonable oncological outcome, it is informative to apply the 3D Cancer mapping for the SPB candidates. It is necessary to assess this criteria with the further follow-up.

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Lindsey, Brooks D., und Graham C. Collins. „Toward Noninvasive Mapping of Diffuse Scattering in the Presence of Motion“. Ultrasonic Imaging 42, Nr. 1 (Januar 2020): 41–52. http://dx.doi.org/10.1177/0161734619899885.

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Ultrasonic coda wave analysis techniques localize defects in fields such as seismography and nondestructive testing. In medical ultrasound, these techniques might provide novel mapping of tissue properties in diseases characterized by local fibrosis. In this work, we present an approach for localizing variation in scattering properties in the diffuse regime with an array transducer in medical ultrasound. This approach estimates coda wave decorrelation as the array is displaced by 0.5 mm, allowing data acquisition at two slightly different spatial locations. An inverse problem is solved as in nondestructive testing based on coda wave decorrelation estimates and a locally-estimated diffusion constant. The developed approach is demonstrated in a tissue-mimicking phantom to assess sensitivity to variation in scattering properties. Next, the ability of the approach for localizing regions of increased multiple scattering in biological tissues is assessed with a large multiple scattering bead in an ex vivo porcine cardiac sample. Through these experiments, the ability to map variation in multiple scattering is demonstrated for the first time, with a mean localization error of 1.42 ± 3.5 mm for this low-resolution mapping technique. While the goal of this technique is to map defects in the diffuse regime rather than to develop a conventional image, contrast ratios in the resulting images were in good agreement with scattering concentrations in phantom studies: 1.98 ± 0.05 for a 2× scattering target, 1.37 ± 0.02 for a 1.4× scattering target, 0.65 ± 0.02 for a 0.7× scattering target, and 0.49 ± 0.03 for a 0.5× scattering targets.

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Hiraoka, Takeshi, Kazuo Hoshino, Katsuhiro Kawashima, Hirotoshi Kato und Yukio Tateno. „A New Gel Using Super Absorbent Polymer for Mapping the Spatial Dose Distributions of Electron Beams by MR Imager“. Medical Dosimetry 18, Nr. 2 (1993): 73–79. http://dx.doi.org/10.1016/0958-3947(93)90035-r.

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Dissertationen zum Thema "Ultrasound beam mapping"

Hlavatý, Radek. „Měření parametrů ultrazvukového svazku“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442538.

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The work deals with methods of measuring the parameters of the ultrasonic beam generated by piezoelectric sensors. The theoretical part contains a literature search of methods for the analysis of the ultrasonic beam generated by piezoelectric transducers with dimensions of units of millimeters. The problematics of measurement using piezoelectric or optical fiber hydrophones is investigated in more detail. The scope of the practical part of the work is the design and implementation of measuring equipment that allows spatial analysis of the beam during propagation by a complicated signal path, for automotive level and concentration sensors of the company Vitesco Technologies s.r.o. The system uses a hydrophone method to measure the ultrasonic beam. Due to test measurements, the repeatability of the measured results is confirmed, the results are discussed in the end.

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Konferenzberichte zum Thema "Ultrasound beam mapping"

Wang, Zhaohui, Pier Ingram, Ragnar Olafsson, Charles L. Greenlee, Robert A. Norwood und Russell S. Witte. „Simulation-based optimization of the acoustoelectric hydrophone for mapping an ultrasound beam“. In SPIE Medical Imaging, herausgegeben von Jan D'hooge und Stephen A. McAleavey. SPIE, 2010. http://dx.doi.org/10.1117/12.844651.

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Usha Devi, C., R. S. Bharat Chandran, R. M. Vasu und A. K. Sood. „Elasticity mapping of tissue mimicking phantoms by remote palpation with a focused ultrasound beam and intensity autocorrelation measurements“. In SPIE Proceedings, herausgegeben von Valery V. Tuchin. SPIE, 2007. http://dx.doi.org/10.1117/12.740958.

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Maleke, Caroline, Jianwen Luo, Assimina A. Pelegri und Elisa E. Konofagou. „Mapping of Regional Cancerous Tissue Mechanical Property Changes Using Harmonic Motion Imaging“. In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-42294.

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Mechanical changes in breast tissues as a result of cancer are usually detected through palpation by the physician and/or self examination. However, physicians are unable to palpate most masses under 1 cm in diameter and microscopic diseases. The goal of our study is to introduce the application of the Harmonic Motion Imaging (HMI), an acoustic radiation force technique, for reliable sensitive tumor detection and real-time monitoring of tumor ablation. Here, we applied the HMI technique using a single-element Focused Ultrasound (FUS) transducer. Due to the highly localized and harmonic nature of the response, the motion characteristics can be directly linked to the regional tissue modulus. In this experiment, a confocal transducer, combining a 4.68 MHz therapy (FUS) and a 7.5 MHz diagnostic (pulse-echo) probe, was used. The FUS beam was further modulated by a low AM continuous wave at 25 Hz. A pulser/receiver was used to drive the pulse-echo transducer at a Pulse Repetition Frequency (PRF) of 5.4 kHz. The radio-frequency (RF) signals were acquired using a standard pulse echo technique. The intensity amplitudes of the FUS beam at the focus (Ispta) were 231 W/cm2 for tumor detection and 1086 W/cm2 for FUS ablation. An analog bandpass filter was used to remove the spectrum of the FUS beam prior to displacement estimation. The resulting axial tissue displacement (i.e., HMI displacement) was estimated using an RF-based speckle tracking technique based on 1D cross-correlation. For tumor mapping, a harmonic radiation force was applied using a 2D raster-scan technique. The 3D HMI image was obtained by combining multiple 2D planes at different depths. The 2D and 3D HMI images in ex vivo breast tissues could detect a benign tumor (2×5×5mm3) surrounded by normal tissue, and a malignant tumor (8×7×5mm3) embedded in glandular and fat tissues. For FUS therapy, temperature measurements and RF signals were acquired during thermal ablation. HMI images during FUS ablation showed lower displacements, indicating thus tissue hardening due to lesion formation at temperatures higher than 50°C. A finite-element model (FEM) simulation was also used to analyze the findings of the experimental results. In conclusion, this technique demonstrates feasibility of the HMI technique for tumor detection and characterization, as well as real-time monitoring of tissue ablation based on the associated tissue elasticity changes.

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Rehman, Hamood, Marvin Klein, Richard Kania, Steve Rapp, Rick McNealy, Martin Fingerhut und Homayoon Ansari. „Sizing Stress Corrosion Cracks Using Laser Ultrasonics“. In 2010 8th International Pipeline Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ipc2010-31278.

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Integrity management decisions related to operating energy transmission pipelines affected by Stress Corrosion Cracking (SCC) represent a formidable challenge to the pipeline industry. Effective management of SCC damage requires the development of tools and technology to identify the occurrence of SCC and to assess the impact of the SCC on pipeline integrity. Development of practical non-destructive evaluation (NDE) solutions for the measurement and evaluation of SCC, including crack depths, is difficult due to the complexity of crack shapes and their inter-relationship and distribution within crack colonies. Laser ultrasonics is an inspection technology using laser beams to generate and detect ultrasonic waves in the pipeline wall to be inspected. Unlike conventional ultrasound, it has a large bandwidth and the beams have a very small (∼0.5mm) footprint. These characteristics make it ideally suited for application as a depth sizing tool for SCC in pipelines. Through a collaborative research project jointly funded by the US Department of Transportation, Pipeline and Hazardous Materials Safety Administration (PHMSA) and PRCI, Applus RTD and its research partners have conclusively shown that laser ultrasonic inspection technology using the Time of Flight Diffraction (TOFD) technique reliably and accurately measures the depth of SCC. In addition, this technique may also be applicable to measuring the depth of other cracks such as seam weld anomalies. The project included the development of a prototype NDE inspection tool for measurement of SCC, and recently culminated with a series of full-scale demonstrations of the tool. This paper describes the detailed technical work conducted to support the development of the tool and validation of the TOFD technique for sizing the depth of SCC. In addition, this paper presents the preliminary results of work on a closely related project that builds on the technology described above to produce an integrated approach and tool for mapping, sizing, and evaluating SCC that filters significant (i.e., deep) cracks from more benign cracks within an SCC colony.

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