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[IEEE 2019 IEEE International Ultrasonics Symposium (IUS) - Glasgow, United Kingdom (2019.10.6-2019.10.9)] 2019 IEEE International Ultrasonics Symposium (IUS) - Non-Contact laser ultrasound (N-CLUS) system for medical imaging and elastography
摘要： MIT Lincoln Laboratory, the Medical Device Realization Center (MEDRC) at MIT, and the Massachusetts General Hospital (MGH) are collaboratively developing a novel optical system that acquires ultrasound images within the human body without physical contact to the patient. The system is termed, non-contact laser ultrasound (N-CLUS) and yields anatomical images in tissue and bone and can also measure elastographic properties, in-vivo, all from an operational standoff of a few inches to several meters as desired. N-CLUS employs a pulsed laser that converts optical energy into ultrasonic waves at the skin surface via photoacoustic mechanisms, while, a laser Doppler vibrometer measures reflected-emerging ultrasonic waves from tissue at depth at the skin surface. The key of the N-CLUS approach is driven by shallow optical absorptivity that creates an acoustic source that enables ultrasound propagation deeper into the tissue. We discuss the motivation of the non-contact laser concept, its development path involving signal generation, skin and eye safe laser measurement, and system design perspectives. Elastogrphic measurements are then demonstrated with determination of bone elastic moduli for beef rib within tissue. N-CLUS images from soft tissue specimens are also compared with commercial ultrasound, showing that the noncontact optical approach may have potential as a viable method in medical ultrasound.
关键词： laser Doppler vibrometry,photoacoustics,non-contact laser ultrasound,medical ultrasound imaging,elastography
更新于2025-09-16 10:30:52
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Toroidally focused sensor array for real-time laser-ultrasonic imaging: the first experimental study
摘要： In this paper we report on the first toroidally focused 2D real-time laser-ultrasonic imaging system and a modified filtered back projection algorithm that can be used in the region near the waist of the astigmatic laser-ultrasonic probe beam. The system is capable of visualizing an acupuncture needle 0.2 mm in diameter located at ~4 cm depth in water. The lateral spatial resolution is better than ~0.32 mm and axial spatial resolution is ~30 μm. The achieved frame rate is up to 30 Hz. The depth dependency of the sensitivity region width and lateral resolution are experimentally measured and discussed. The array is intended to be used as a part of combined real-time photoacoustic and laser-ultrasonic imaging system.
关键词： laser ultrasound imaging,back projection,tomography,real-time,focused array,laser ultrasound,toroidal array
更新于2025-09-16 10:30:52
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[IEEE 2019 Far East NDT New Technology & Application Forum (FENDT) - Qingdao, Shandong province, China (2019.6.24-2019.6.27)] 2019 Far East NDT New Technology & Application Forum (FENDT) - Visual Detection of AM Surface Defects Based on Laser Ultrasound Technology
摘要： Selective Laser Melting (SLM) process is a kind of Additive Manufacturing (AM) method, which can process parts with arbitrary complex geometry. However, macro-defects will destroy the mechanical properties of metal materials manufactured by SLM. Laser ultrasound can excite broadband surface waves and realize non-contact nondestructive testing of surface defects. In this paper, 316L stainless steel samples are prepared by SLM process are used for laser ultrasonic detection. According to the diffraction phenomenon of surface wave at the defect, a laser ultrasonic B-scan detection platform is built. The B-scan images of different length defects on the sample surface are obtained, and the quantitative detection of surface defects is realized quickly. In order to further improve the signal-to-noise ratio and the accuracy of imaging detection, EEMD (Ensemble Empirical Mode Decomposition) denoising is applied to the collected ultrasonic signal, which improves the accuracy of imaging, makes the signal more stable and realizes the visual detection of surface length defects clearly and intuitively.
关键词： b-scan,additive manufacturing,laser ultrasound technology,EEMD
更新于2025-09-16 10:30:52
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Full noncontact laser ultrasound: first human data
摘要： Full noncontact laser ultrasound (LUS) imaging has several distinct advantages over current medical ultrasound (US) technologies: elimination of the coupling mediums (gel/water), operator-independent image quality, improved repeatability, and volumetric imaging. Current light-based ultrasound utilizing tissue-penetrating photoacoustics (PA) generally uses traditional piezoelectric transducers in contact with the imaged tissue or carries an optical fiber detector close to the imaging site. Unlike PA, the LUS design presented here minimizes the optical penetration and specifically restricts optical-to-acoustic energy transduction at the tissue surface, maximizing the generated acoustic source amplitude. With an appropriate optical design and interferometry, any exposed tissue surfaces can become viable acoustic sources and detectors. LUS operates analogously to conventional ultrasound but uses light instead of piezoelectric elements. Here, we present full noncontact LUS results, imaging targets at ~5 cm depths and at a meter-scale standoff from the target surface. Experimental results demonstrating volumetric imaging and the first LUS images on humans are presented, all at eye- and skin-safe optical exposure levels. The progression of LUS imaging from tissue-mimicking phantoms, to excised animal tissue, to humans in vivo is shown, with validation from conventional ultrasound images. The LUS system design insights and results presented here inspire further LUS development and are a significant step toward the clinical implementation of LUS.
关键词： photoacoustics,noncontact imaging,volumetric imaging,human imaging,laser ultrasound
更新于2025-09-12 10:27:22