High-quality imaging in photoacoustic computed tomography (PACT) requires a high-channel count system for dense spatial sampling to avoid aliasing-related artifacts. To reduce system complexity, various image reconstruction approaches, such as model-based (MB) and deep learning based methods, have been explored to mitigate the artifacts associated with sparse-view acquisition. However, the explored methods use discrete representation to formulate the reconstruction problem, which is ill-conditioned and is thus prone to measurement errors and discretization errors. Meanwhile, the extent of the ill-condition of the reconstruction problem scales with the discretization resolution. In this work, an implicit neural representation (INR) framework is proposed for image reconstruction in PACT with ring transducer arrays to address these issues. Specifically, the initial heat distribution is represented as a continuous function of spatial coordinates using a multi-layer perceptron (MLP). The weights of the MLP are then determined by a training process in a self-supervised manner, by minimizing the errors between the measured and model-predicted PA signals. After training, PA images can be mapped by feeding the coordinates to the network. Simulation and phantom experiments showed that the INR method outperforms the universal back-projection and MB methods in preserving image fidelity and artifacts suppression for the same acquisition condition. In the experimental data, the INR method improved signal-to-noise-ratio (generalized contrast-to-noise-ratio) by 1.1-24.0 dB (0.037-0.716), compared to the other methods. These results clearly demonstrated the value of INR for high-quality PACT image reconstruction with sparse data and its potential in reducing the complexity of PACT systems.
{"title":"Implicit neural representation for sparse-view photoacoustic computed tomography.","authors":"Shaoqi Huang, Bowei Yao, Shilong Cui, Haizhao Dai, Qing Wu, Youshen Xiao, Fei Gao, Jingyi Yu, Yuyao Zhang, Xiran Cai","doi":"10.1016/j.ultras.2026.107991","DOIUrl":"https://doi.org/10.1016/j.ultras.2026.107991","url":null,"abstract":"<p><p>High-quality imaging in photoacoustic computed tomography (PACT) requires a high-channel count system for dense spatial sampling to avoid aliasing-related artifacts. To reduce system complexity, various image reconstruction approaches, such as model-based (MB) and deep learning based methods, have been explored to mitigate the artifacts associated with sparse-view acquisition. However, the explored methods use discrete representation to formulate the reconstruction problem, which is ill-conditioned and is thus prone to measurement errors and discretization errors. Meanwhile, the extent of the ill-condition of the reconstruction problem scales with the discretization resolution. In this work, an implicit neural representation (INR) framework is proposed for image reconstruction in PACT with ring transducer arrays to address these issues. Specifically, the initial heat distribution is represented as a continuous function of spatial coordinates using a multi-layer perceptron (MLP). The weights of the MLP are then determined by a training process in a self-supervised manner, by minimizing the errors between the measured and model-predicted PA signals. After training, PA images can be mapped by feeding the coordinates to the network. Simulation and phantom experiments showed that the INR method outperforms the universal back-projection and MB methods in preserving image fidelity and artifacts suppression for the same acquisition condition. In the experimental data, the INR method improved signal-to-noise-ratio (generalized contrast-to-noise-ratio) by 1.1-24.0 dB (0.037-0.716), compared to the other methods. These results clearly demonstrated the value of INR for high-quality PACT image reconstruction with sparse data and its potential in reducing the complexity of PACT systems.</p>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"164 ","pages":"107991"},"PeriodicalIF":4.1,"publicationDate":"2026-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146228867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-07DOI: 10.1016/j.ultras.2026.107997
Zitong Mai, Xiping He, Maiwei Liao, Zhibo Li
This study proposes a frequency tunable ultrasonic resonator based on a variable mass method, in which a metal ring, i.e., a tuning frequency ring (TFR) is mounted on the resonator. The resonant frequency of the resonator is adjusted by altering the position of the TFR, which introduces changes in both inertia and stiffness. LTspice were conducted to investigate the effects of the TFR’s size, material, and position on the resonant frequency, with experimental measurements further validating the results. Contrary to the conventional belief that adding mass lowers the frequency, the study reveals that placing the TFR near the displacement node can increase the resonant frequency. The results also demonstrate that the tuning range of the system can be controlled by modifying the TFR’s geometry and material properties. For a resonator with a resonant frequency of 28 kHz, when the mass of the TFR is about 36 g, studies show that the maximum tunable frequency range is 9 kHz. Based on the energy method, the equivalent mass and stiffness of the resonator were calculated using the SECM (Segmented Equivalent Circuit Model) and cubic spline interpolation, explaining the physical mechanism of frequency tuning using the variable mass method, providing a practical solution for achieving wide-range frequency tuning in ultrasonic resonators.
{"title":"Study on frequency tunable resonators via variable mass","authors":"Zitong Mai, Xiping He, Maiwei Liao, Zhibo Li","doi":"10.1016/j.ultras.2026.107997","DOIUrl":"10.1016/j.ultras.2026.107997","url":null,"abstract":"<div><div>This study proposes a frequency tunable ultrasonic resonator based on a variable mass method, in which a metal ring, i.e., a tuning frequency ring (TFR) is mounted on the resonator. The resonant frequency of the resonator is adjusted by altering the position of the TFR, which introduces changes in both inertia and stiffness. LTspice were conducted to investigate the effects of the TFR’s size, material, and position on the resonant frequency, with experimental measurements further validating the results. Contrary to the conventional belief that adding mass lowers the frequency, the study reveals that placing the TFR near the displacement node can increase the resonant frequency. The results also demonstrate that the tuning range of the system can be controlled by modifying the TFR’s geometry and material properties. For a resonator with a resonant frequency of 28 kHz, when the mass of the TFR is about 36 g, studies show that the maximum tunable frequency range is 9 kHz. Based on the energy method, the equivalent mass and stiffness of the resonator were calculated using the SECM (Segmented Equivalent Circuit Model) and cubic spline interpolation, explaining the physical mechanism of frequency tuning using the variable mass method, providing a practical solution for achieving wide-range frequency tuning in ultrasonic resonators.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"163 ","pages":"Article 107997"},"PeriodicalIF":4.1,"publicationDate":"2026-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146158575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-06DOI: 10.1016/j.ultras.2026.107999
Ferdousi Sabera Rawnaque , Julianna C. Simon
Acoustic cavitation, or the rapid growth and collapse of pre-existing bubble nuclei under a varying acoustic pressure field, plays a critical role in the safety and efficacy of biomedical ultrasound. However, the availability and behavior of bubble nuclei, which act as seeds for acoustic cavitation, remain largely unexplored in biological tissues. In this study we evaluated the spatial location of bubble nuclei and cavitation thresholds in biological systems by culturing four rat-derived healthy and cancerous cell lines (musculoskeletal L-6 and L-8; hepatic BRL-3A, and McA-RH7777) in two commercial 3D scaffolds: PureCol® EZ-Gel and Cultrex® Ultimatrix. A single element 3.68 MHz focused ultrasound transducer (f#=1) induced low-density cavitation with pulse durations of 10–300 μs at 1 Hz PRF and peak negative pressures up to p- = 6.07 ± 0.13 MPa. The spatial locations of bubbles were monitored and captured using brightfield microscopy and high-speed photography (20,000 fps). Bubble formation was observed exclusively in the extracellular scaffold, with no intracellular cavitation detected in any of the 40 cell culture samples. In 3D cell cultures of healthy musculoskeletal cells, lower cavitation thresholds (∼4.1 MPa) were observed compared to their cancerous counterparts (∼4.9 MPa; p < 0.001) for 200 μs pulses, possibly due to the ECM-modifying behavior of L-8; however, the trend did not extend to liver cells where cavitation thresholds were similar. Increasing pulse length consistently reduced cavitation thresholds across all cell-scaffold combinations. Together, these results suggest that cavitation is predominantly extracellular, which may have implications for the safety and efficacy of emerging therapeutic ultrasound applications.
{"title":"Evaluation of the location and probability of acoustic cavitation in healthy and cancerous 3D cell cultures","authors":"Ferdousi Sabera Rawnaque , Julianna C. Simon","doi":"10.1016/j.ultras.2026.107999","DOIUrl":"10.1016/j.ultras.2026.107999","url":null,"abstract":"<div><div>Acoustic cavitation, or the rapid growth and collapse of pre-existing bubble nuclei under a varying acoustic pressure field, plays a critical role in the safety and efficacy of biomedical ultrasound. However, the availability and behavior of bubble nuclei, which act as seeds for acoustic cavitation, remain largely unexplored in biological tissues. In this study we evaluated the spatial location of bubble nuclei and cavitation thresholds in biological systems by culturing four rat-derived healthy and cancerous cell lines (musculoskeletal L-6 and L-8; hepatic BRL-3A, and McA-RH7777) in two commercial 3D scaffolds: PureCol® EZ-Gel and Cultrex® Ultimatrix. A single element 3.68 MHz focused ultrasound transducer (f#=1) induced low-density cavitation with pulse durations of 10–300 μs at 1 Hz PRF and peak negative pressures up to p- = 6.07 ± 0.13 MPa. The spatial locations of bubbles were monitored and captured using brightfield microscopy and high-speed photography (20,000 fps). Bubble formation was observed exclusively in the extracellular scaffold, with no intracellular cavitation detected in any of the 40 cell culture samples. In 3D cell cultures of healthy musculoskeletal cells, lower cavitation thresholds (∼4.1 MPa) were observed compared to their cancerous counterparts (∼4.9 MPa; p < 0.001) for 200 μs pulses, possibly due to the ECM-modifying behavior of L-8; however, the trend did not extend to liver cells where cavitation thresholds were similar. Increasing pulse length consistently reduced cavitation thresholds across all cell-scaffold combinations. Together, these results suggest that cavitation is predominantly extracellular, which may have implications for the safety and efficacy of emerging therapeutic ultrasound applications.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"163 ","pages":"Article 107999"},"PeriodicalIF":4.1,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-06DOI: 10.1016/j.ultras.2026.107998
Jinbum Kang , Seongjun Park , Eonho Lee , Hyunwoo Cho , Kangsik Kim , Min Jung Kim , Yangmo Yoo
While mammography is the standard modality for detecting microcalcifications (MCs), their real-time detection with ultrasound imaging can be invaluable, particularly for guiding biopsies. Ultrasound twinkling artifact (TA) imaging allows the sensitive distinction of MCs from background breast tissue; however, it may also be confounded with blood flow in Doppler mode during in vivo scanning. In this paper, we propose a new MC imaging method that classifies TA and blood flow signals to enable in vivo detection of breast MCs. Based on the signal characteristics of TA and blood flow, two optimal features (i.e., mean frequency and spectrum bandwidth) are extracted and used to train a machine learning classifier. To train the classification model, tissue-mimicking and chicken breast phantom containing normal wire (285 in diameter), MC wire (300 in diameter) and micro-vessel tube (1 in diameter) were fabricated, and training and validation datasets were acquired under varying flow velocities and pulse repetition frequencies (PRFs). Among the four classifiers, i.e., k-nearest neighbors (KNN), support vector machine (SVM), naïve Bayes and quadratic discriminant, trained with the two optimal features, the SVM achieved the highest accuracy (95.25 %), whereas the remaining models also exhibited strong performance with accuracies exceeding 92 %. The trained SVM model was then validated on a chicken breast MC phantom and in vivo human breast data, and they showed good agreement with color Doppler imaging. The feasibility study demonstrated that the proposed classification approach may enable effective in vivo detection and improve diagnostic accuracy, especially in cases with complex flow patterns in breast lesions.
{"title":"Classification of twinkling artifacts and blood flow for in vivo detection of breast microcalcifications","authors":"Jinbum Kang , Seongjun Park , Eonho Lee , Hyunwoo Cho , Kangsik Kim , Min Jung Kim , Yangmo Yoo","doi":"10.1016/j.ultras.2026.107998","DOIUrl":"10.1016/j.ultras.2026.107998","url":null,"abstract":"<div><div>While mammography is the standard modality for detecting microcalcifications (MCs), their real-time detection with ultrasound imaging can be invaluable, particularly for guiding biopsies. Ultrasound twinkling artifact (TA) imaging allows the sensitive distinction of MCs from background breast tissue; however, it may also be confounded with blood flow in Doppler mode during <em>in vivo</em> scanning. In this paper, we propose a new MC imaging method that classifies TA and blood flow signals to enable <em>in vivo</em> detection of breast MCs. Based on the signal characteristics of TA and blood flow, two optimal features (i.e., mean frequency and spectrum bandwidth) are extracted and used to train a machine learning classifier. To train the classification model, tissue-mimicking and chicken breast phantom containing normal wire (285 <span><math><mrow><mi>μ</mi><mi>m</mi></mrow></math></span> in diameter), MC wire (300 <span><math><mrow><mi>μ</mi><mi>m</mi></mrow></math></span> in diameter) and micro-vessel tube (1 <span><math><mrow><mi>mm</mi></mrow></math></span> in diameter) were fabricated, and training and validation datasets were acquired under varying flow velocities and pulse repetition frequencies (PRFs). Among the four classifiers, i.e., k-nearest neighbors (KNN), support vector machine (SVM), naïve Bayes and quadratic discriminant, trained with the two optimal features, the SVM achieved the highest accuracy (95.25 %), whereas the remaining models also exhibited strong performance with accuracies exceeding 92 %. The trained SVM model was then validated on a chicken breast MC phantom and <em>in vivo</em> human breast data, and they showed good agreement with color Doppler imaging. The feasibility study demonstrated that the proposed classification approach may enable effective <em>in vivo</em> detection and improve diagnostic accuracy, especially in cases with complex flow patterns in breast lesions.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"163 ","pages":"Article 107998"},"PeriodicalIF":4.1,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146143725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-06DOI: 10.1016/j.ultras.2026.107995
MC. Herrera , F. Sundblad , Ari. Salmi , CR. Dickerson , K. Raum
This feasibility study evaluated quantitative ultrasound imaging of bone (QUSIB) for non-ionizing assessment of rib quality in the context of breast cancer treatment. In silico, microcomputed tomography-based rib models simulated five-year of the effects of radiation and bisphosphonate therapy. Broadband ultrasound propagation (6-MHz center frequency, 128-element array) yielded backscatter and attenuation coefficients, which were related to structural and material parameters via univariate and partial least squares (PLS) regression analyses with 5-fold cross-validation. The strongest univariate correlations were observed for trabecular total bone volume fraction (BV/TVtb) and cortical porosity with attenuation at 7–8 MHz. PLS models significantly predicted trabecular BV/TVtb (R2 = 0.50; p < 0.001) and cortical porosity (R2 = 0.58; p < 0.001). Treatment-dependent spectral shifts in backscatter and attenuation coefficients confirmed sensitivity to pathological changes.
In-vivo QUSIB measurements at the antero-lateral 4th–6th ribs and at the tibia midshaft in n = 10 healthy volunteers produced apparent integrated backscatter and attenuation values that closely matched in-silico distributions (p > 0.01) and did not differ significantly from tibia measurements.
These results demonstrate that QUSIB backscatter biomarkers robustly reflect rib microstructure and treatment-induced alterations, supporting their potential for fracture-risk assessment in breast cancer patients.
本可行性研究评估了骨定量超声成像（QUSIB）在乳腺癌治疗中对肋骨质量的非电离评估。在计算机上，基于微计算机断层扫描的肋骨模型模拟了放射和双膦酸盐治疗5年的影响。宽带超声传播（中心频率为6mhz， 128元阵列）通过单变量和偏最小二乘（PLS）回归分析获得了与结构和材料参数相关的反向散射和衰减系数，并进行了5倍交叉验证。单变量相关性最强的是骨小梁总骨体积分数（BV/TVtb）和皮质孔隙度，在7-8 MHz时衰减。PLS模型显著预测小梁BV/TVtb （R2 = 0.50; p < 0.001）和皮质孔隙度（R2 = 0.58; p < 0.001）。治疗相关的后向散射光谱偏移和衰减系数证实了对病理变化的敏感性。在n = 10名健康志愿者中，在第4 -第6肋骨前外侧和胫骨中轴处的体内QUSIB测量产生了明显的综合后向散射和衰减值，与计算机分布密切匹配（p > 0.01），与胫骨测量值无显著差异。这些结果表明，QUSIB后向散射生物标志物强有力地反映了肋骨微观结构和治疗引起的改变，支持了它们在乳腺癌患者骨折风险评估中的潜力。
{"title":"Rib quality assessment using quantitative ultrasound imaging of bone","authors":"MC. Herrera , F. Sundblad , Ari. Salmi , CR. Dickerson , K. Raum","doi":"10.1016/j.ultras.2026.107995","DOIUrl":"10.1016/j.ultras.2026.107995","url":null,"abstract":"<div><div>This feasibility study evaluated quantitative ultrasound imaging of bone (QUSIB) for non-ionizing assessment of rib quality in the context of breast cancer treatment. <em>In silico</em>, microcomputed tomography-based rib models simulated five-year of the effects of radiation and bisphosphonate therapy. Broadband ultrasound propagation (6-MHz center frequency, 128-element array) yielded backscatter and attenuation coefficients, which were related to structural and material parameters via univariate and partial least squares (PLS) regression analyses with 5-fold cross-validation. The strongest univariate correlations were observed for trabecular total bone volume fraction (<em>BV/TV<sub>tb</sub></em>) and cortical porosity with attenuation at 7–8 MHz. PLS models significantly predicted trabecular <em>BV/TV<sub>tb</sub></em> (R<sup>2</sup> = 0.50; p < 0.001) and cortical porosity (R<sup>2</sup> = 0.58; p < 0.001). Treatment-dependent spectral shifts in backscatter and attenuation coefficients confirmed sensitivity to pathological changes.</div><div><em>In-vivo</em> QUSIB measurements at the antero-lateral 4th–6th ribs and at the tibia midshaft in <em>n</em> = 10 healthy volunteers produced apparent integrated backscatter and attenuation values that closely matched <em>in-silico</em> distributions (p > 0.01) and did not differ significantly from tibia measurements.</div><div>These results demonstrate that QUSIB backscatter biomarkers robustly reflect rib microstructure and treatment-induced alterations, supporting their potential for fracture-risk assessment in breast cancer patients.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"163 ","pages":"Article 107995"},"PeriodicalIF":4.1,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-06DOI: 10.1016/j.ultras.2026.107996
Shengqi Peng, Xinhao Sun, Tinghao Yang, Yi Quan, Jun Chen, Lifei Lou, Chunlong Fei, Yintang Yang
Crosstalk, a detrimental phenomenon in ultrasonic arrays, compromises resolution, penetration depth, and diagnostic reliability. This study examines the impact of kerf filling materials on crosstalk suppression and imaging performance via integrated numerical simulations and experimental validation. Two fillers with contrasting acoustic properties were evaluated: rigid epoxy resin (Epo-Tek 301) and soft silicone rubber (RTV-664). RTV-664, exhibiting lower acoustic impedance and higher attenuation, demonstrated reduced mechanical coupling between adjacent elements. To validate this, a 128-element linear array was designed and fabricated, with its electrical, transceiver, and crosstalk characteristics systematically assessed through finite element simulations, phantom experiments, and "in vivo" imaging. Results indicate that RTV-664 reduced crosstalk in first- to third-order adjacent elements by an average of 33.4% across the 4-8 MHz bandwidth, aligning with simulated predictions. Imaging tests further confirmed that RTV-664-based arrays achieved broader bandwidth, enhanced field uniformity, and superior image quality, including improved resolution, penetration depth, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). These findings underscore the critical role of kerf filling materials selection in crosstalk mitigation, offering theoretical insights and experimental evidence for optimizing ultrasonic array design toward high-performance medical imaging.
串扰是超声波阵列中的一种有害现象，它会影响分辨率、穿透深度和诊断可靠性。本研究通过综合数值模拟和实验验证，探讨了切口填充材料对串扰抑制和成像性能的影响。对两种声学性能对比的填料进行了评价：硬质环氧树脂（epoo - tek 301）和软硅橡胶（RTV-664）。RTV-664表现出较低的声阻抗和较高的衰减，表明相邻单元之间的机械耦合减少。为了验证这一点，设计并制造了一个128元线性阵列，并通过有限元模拟、模拟实验和“体内”成像系统地评估了其电气、收发器和串扰特性。结果表明，RTV-664在4-8 MHz带宽范围内，将一阶至三阶相邻单元的串扰平均降低了33.4%，与模拟预测一致。成像测试进一步证实，基于rtv -664的阵列具有更宽的带宽、增强的场均匀性和更好的图像质量，包括改进的分辨率、穿透深度、信噪比（SNR）和对比噪声比（CNR）。这些发现强调了切口填充材料的选择在减少串扰中的关键作用，为优化超声阵列设计以实现高性能医学成像提供了理论见解和实验证据。
{"title":"Kerf filling material: Suppressing crosstalk and enhancing imaging quality in ultrasonic arrays.","authors":"Shengqi Peng, Xinhao Sun, Tinghao Yang, Yi Quan, Jun Chen, Lifei Lou, Chunlong Fei, Yintang Yang","doi":"10.1016/j.ultras.2026.107996","DOIUrl":"https://doi.org/10.1016/j.ultras.2026.107996","url":null,"abstract":"<p><p>Crosstalk, a detrimental phenomenon in ultrasonic arrays, compromises resolution, penetration depth, and diagnostic reliability. This study examines the impact of kerf filling materials on crosstalk suppression and imaging performance via integrated numerical simulations and experimental validation. Two fillers with contrasting acoustic properties were evaluated: rigid epoxy resin (Epo-Tek 301) and soft silicone rubber (RTV-664). RTV-664, exhibiting lower acoustic impedance and higher attenuation, demonstrated reduced mechanical coupling between adjacent elements. To validate this, a 128-element linear array was designed and fabricated, with its electrical, transceiver, and crosstalk characteristics systematically assessed through finite element simulations, phantom experiments, and \"in vivo\" imaging. Results indicate that RTV-664 reduced crosstalk in first- to third-order adjacent elements by an average of 33.4% across the 4-8 MHz bandwidth, aligning with simulated predictions. Imaging tests further confirmed that RTV-664-based arrays achieved broader bandwidth, enhanced field uniformity, and superior image quality, including improved resolution, penetration depth, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). These findings underscore the critical role of kerf filling materials selection in crosstalk mitigation, offering theoretical insights and experimental evidence for optimizing ultrasonic array design toward high-performance medical imaging.</p>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"164 ","pages":"107996"},"PeriodicalIF":4.1,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146228855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.ultras.2026.107969
Feilong Ji , Yan Zhou , Lihong Zhou , Bowen Dong , Shuo Duan , Zeqi Hu , Xunpeng Qin
The morphology of deposition layer in direct energy deposition-Arc (DED-Arc) critically affects the forming accuracy and performance of the manufactured components. To address morphology control challenges, this study investigates the role of ultrasonic amplitude in geometric characteristics and wetting behavior of mild steel deposition layers. An ultrasonic-assisted DED-Arc platform was established, integrating numerical models for ultrasonic field propagation and molten pool fluid dynamics to analyze temperature gradients under optimal ultrasonic excitation source. Simulation results revealed that positioning the ultrasonic excitation source at the substrate’s geometric center achieved uniform vibration distribution. Ultrasonic vibration reduced the molten pool’s maximum temperature gradient by 28.2% (horizontal) and 24.9% (vertical), enhancing thermal uniformity. Experimental findings demonstrated that increasing ultrasonic amplitude (0–16 μm) decreased deposition layer height (3.09–2.56 mm), depth (1.98–1.60 mm), contact angle (57°-44°) and dilution rate (38.1%–33.5%), while increasing width (8.21–9.04 mm). The surface roughness (Ra, Rz) decreased by 20.3% and 39.3% respectively. High-speed imaging of glycerol droplet spreading revealed that ultrasonic vibration reduced contact angles from 58° to 46° and increased spreading area by 38.2% within 2 s, demonstrating enhanced wettability. A critical threshold of 16 μm amplitude was identified, beyond which molten pool instability degraded morphology. Ultrasonic vibration enhanced wetting by generating a viscous momentum transfer layer at the melt-substrate interface, driving outward expansion of the triple-phase contact line. These results provide quantitative guidelines for optimizing DED-Arc processes in automotive and aerospace applications requiring precise morphology control.
{"title":"Effect of ultrasonic amplitude on morphology and wetting behavior of mild steel deposition layer in direct energy deposition-Arc","authors":"Feilong Ji , Yan Zhou , Lihong Zhou , Bowen Dong , Shuo Duan , Zeqi Hu , Xunpeng Qin","doi":"10.1016/j.ultras.2026.107969","DOIUrl":"10.1016/j.ultras.2026.107969","url":null,"abstract":"<div><div>The morphology of deposition layer in direct energy deposition-Arc (DED-Arc) critically affects the forming accuracy and performance of the manufactured components. To address morphology control challenges, this study investigates the role of ultrasonic amplitude in geometric characteristics and wetting behavior of mild steel deposition layers. An ultrasonic-assisted DED-Arc platform was established, integrating numerical models for ultrasonic field propagation and molten pool fluid dynamics to analyze temperature gradients under optimal ultrasonic excitation source. Simulation results revealed that positioning the ultrasonic excitation source at the substrate’s geometric center achieved uniform vibration distribution. Ultrasonic vibration reduced the molten pool’s maximum temperature gradient by 28.2% (horizontal) and 24.9% (vertical), enhancing thermal uniformity. Experimental findings demonstrated that increasing ultrasonic amplitude (0–16 μm) decreased deposition layer height (3.09–2.56 mm), depth (1.98–1.60 mm), contact angle (57°-44°) and dilution rate (38.1%–33.5%), while increasing width (8.21–9.04 mm). The surface roughness (Ra, Rz) decreased by 20.3% and 39.3% respectively. High-speed imaging of glycerol droplet spreading revealed that ultrasonic vibration reduced contact angles from 58° to 46° and increased spreading area by 38.2% within 2 s, demonstrating enhanced wettability. A critical threshold of 16 μm amplitude was identified, beyond which molten pool instability degraded morphology. Ultrasonic vibration enhanced wetting by generating a viscous momentum transfer layer at the melt-substrate interface, driving outward expansion of the triple-phase contact line. These results provide quantitative guidelines for optimizing DED-Arc processes in automotive and aerospace applications requiring precise morphology control.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"163 ","pages":"Article 107969"},"PeriodicalIF":4.1,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146143744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-31DOI: 10.1016/j.ultras.2026.107981
Laurence Clarkson, Frederic Cegla
Structural health monitoring often involves temperature measurement. However, traditional sensors cannot measure subsurface temperature non-invasively, making them unsuitable for monitoring temperature-driven damage mechanisms such as high-cycle thermal fatigue. This limitation arises, in part, due to effective thermal low-pass filtering caused by material properties. A previous feasibility study demonstrated that subsurface temperature can be inferred non-invasively in mild steel subjected to uniform heating. This was achieved using the ultrasonic-based inverse thermal modelling (ITM) method, which assumes the temperature of a component can be described by a 1D system.
This study investigated the behaviour of ITM under non-uniform heating applied to the ‘inaccessible’ surface of a stainless steel sample through experiments and simulations. The experimental results show that ITM over-predicts temperature by as much as 120% when the heated region is small compared with the 10 mm ultrasonic beam size. In simulation, the overestimation was reduced as the size of the heating source increased, effectively making the temperature distribution more uniform across the volume through which the ultrasonic wave travels. Despite the overestimation under non-uniform heating, ITM overcomes the thermal low-pass filtering, allowing the detection of thermal transients compared with a thermocouple mounted on the ‘accessible’ surface of a component.
{"title":"Limitations of the 1D inverse thermal modelling method for ultrasonic thermometry","authors":"Laurence Clarkson, Frederic Cegla","doi":"10.1016/j.ultras.2026.107981","DOIUrl":"10.1016/j.ultras.2026.107981","url":null,"abstract":"<div><div>Structural health monitoring often involves temperature measurement. However, traditional sensors cannot measure subsurface temperature non-invasively, making them unsuitable for monitoring temperature-driven damage mechanisms such as high-cycle thermal fatigue. This limitation arises, in part, due to effective thermal low-pass filtering caused by material properties. A previous feasibility study demonstrated that subsurface temperature can be inferred non-invasively in mild steel subjected to uniform heating. This was achieved using the ultrasonic-based inverse thermal modelling (ITM) method, which assumes the temperature of a component can be described by a 1D system.</div><div>This study investigated the behaviour of ITM under non-uniform heating applied to the ‘inaccessible’ surface of a stainless steel sample through experiments and simulations. The experimental results show that ITM over-predicts temperature by as much as 120% when the heated region is small compared with the 10<!--> <!-->mm ultrasonic beam size. In simulation, the overestimation was reduced as the size of the heating source increased, effectively making the temperature distribution more uniform across the volume through which the ultrasonic wave travels. Despite the overestimation under non-uniform heating, ITM overcomes the thermal low-pass filtering, allowing the detection of thermal transients compared with a thermocouple mounted on the ‘accessible’ surface of a component.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"163 ","pages":"Article 107981"},"PeriodicalIF":4.1,"publicationDate":"2026-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146120399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-30DOI: 10.1016/j.ultras.2026.107983
Enze Chen, Paul Fromme
This study investigated the feasibility of guided ultrasonic wave monitoring of bone attachment to uncemented orthopaedic implants during the rehabilitation process (osseointegration), which is crucial for implant stability and long-term survival. Experiments were conducted using a simplified three-layer synthetic bone model of an intraosseous transcutaneous amputation prosthesis (ITAP) implant, used for femoral amputee patients, where epoxy curing simulated the bone ingrowth process associated with increasing bone-implant interface layer stiffness, representing the early stages of osseointegration. Longitudinal guided wave signals were excited and recorded at the distal end of the percutaneous part of the stainless-steel implant. Finite element analysis (FEA) was validated from the experiments and employed to investigate the sensitivity and wave mode selection. FEA simulations showed frequency shifts and group velocity changes of the guided wave modes with increased osseointegration, matching theoretical predictions. Evaluation of the reflected wave pulse in the time domain for both experimental monitoring and FEA simulations showed a significant increase in arrival time (10%) and amplitude drop (>50%). The results showed that the longitudinal guided waves are sensitive to stiffness changes during the bone healing process and provide insights for the development of in-vivo osseointegration monitoring during patient rehabilitation.
{"title":"Guided ultrasonic wave monitoring for osseointegration assessment of an intraosseous transcutaneous amputation prosthesis","authors":"Enze Chen, Paul Fromme","doi":"10.1016/j.ultras.2026.107983","DOIUrl":"10.1016/j.ultras.2026.107983","url":null,"abstract":"<div><div>This study investigated the feasibility of guided ultrasonic wave monitoring of bone attachment to uncemented orthopaedic implants during the rehabilitation process (osseointegration), which is crucial for implant stability and long-term survival. Experiments were conducted using a simplified three-layer synthetic bone model of an intraosseous transcutaneous amputation prosthesis (ITAP) implant, used for femoral amputee patients, where epoxy curing simulated the bone ingrowth process associated with increasing bone-implant interface layer stiffness, representing the early stages of osseointegration. Longitudinal guided wave signals were excited and recorded at the distal end of the percutaneous part of the stainless-steel implant. Finite element analysis (FEA) was validated from the experiments and employed to investigate the sensitivity and wave mode selection. FEA simulations showed frequency shifts and group velocity changes of the guided wave modes with increased osseointegration, matching theoretical predictions. Evaluation of the reflected wave pulse in the time domain for both experimental monitoring and FEA simulations showed a significant increase in arrival time (10%) and amplitude drop (>50%). The results showed that the longitudinal guided waves are sensitive to stiffness changes during the bone healing process and provide insights for the development of <em>in-vivo</em> osseointegration monitoring during patient rehabilitation.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"163 ","pages":"Article 107983"},"PeriodicalIF":4.1,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146133259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-30DOI: 10.1016/j.ultras.2026.107982
Atsushi Hosokawa
Experimental observation of the piezoelectric signals generated in cancellous bone by an ultrasound wave was performed using “piezoelectric cells (PE-cells)”. The PE-cell, in which a cancellous bone specimen is used as a piezoelectric element, can correspond to an ultrasound receiver. In this study, two cancellous bone specimens in which the pore spaces were saturated with air and two waters with normal and low conductivities were used. The piezoelectric signals generated in the air- and water-saturated cancellous bone specimens by an ultrasound wave and the ultrasound signals propagated through the specimens were observed. The amplitudes of the piezoelectric signals in the water-saturated cancellous bone specimens were approximately four times of the amplitude in the air-saturated specimen. Both fast and slow waves, which can propagate mainly in the trabecular elements and the pore fluid, respectively, could be observed for the ultrasound signals in the water-saturated cancellous bone specimens, but only the fast wave could be observed for the signal in the air-saturated specimen. From the observed results, it was suggested that the piezoelectric signal generated in cancellous bone by an ultrasound wave could be largely associated with the motion of the pore fluid.
{"title":"Piezoelectrical signals generated in air- and water-saturated cancellous bones by an ultrasound wave","authors":"Atsushi Hosokawa","doi":"10.1016/j.ultras.2026.107982","DOIUrl":"10.1016/j.ultras.2026.107982","url":null,"abstract":"<div><div>Experimental observation of the piezoelectric signals generated in cancellous bone by an ultrasound wave was performed using “piezoelectric cells (PE-cells)”. The PE-cell, in which a cancellous bone specimen is used as a piezoelectric element, can correspond to an ultrasound receiver. In this study, two cancellous bone specimens in which the pore spaces were saturated with air and two waters with normal and low conductivities were used. The piezoelectric signals generated in the air- and water-saturated cancellous bone specimens by an ultrasound wave and the ultrasound signals propagated through the specimens were observed. The amplitudes of the piezoelectric signals in the water-saturated cancellous bone specimens were approximately four times of the amplitude in the air-saturated specimen. Both fast and slow waves, which can propagate mainly in the trabecular elements and the pore fluid, respectively, could be observed for the ultrasound signals in the water-saturated cancellous bone specimens, but only the fast wave could be observed for the signal in the air-saturated specimen. From the observed results, it was suggested that the piezoelectric signal generated in cancellous bone by an ultrasound wave could be largely associated with the motion of the pore fluid.</div></div>","PeriodicalId":23522,"journal":{"name":"Ultrasonics","volume":"163 ","pages":"Article 107982"},"PeriodicalIF":4.1,"publicationDate":"2026-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146120385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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