• Title/Summary/Keyword: 광대역 초음파 감쇠

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Correlations between Acoustic Properties and Bone Mineral Density in Bovine Femoral Trabecular Bone In Vitro (생체 외 조건의 소 대퇴골 해면질골에서 음향특성과 골밀도 사이의 상관관계)

  • Hwang, Kyo-Seung;Seo, Dong-Wan;Lee, Kang-Il
    • The Journal of the Acoustical Society of Korea
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    • v.31 no.4
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    • pp.244-252
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    • 2012
  • The purpose of the present study is to investigate the correlations between acoustic properties, such as speed of sound and normalized broadband ultrasound attenuation, and bone mineral density in femur with high fracture risk. The speed of sound and the normalized broadband ultrasound attenuation in 15 bovine femoral trabecular bone samples in vitro were measured by using a through-transmission method with two matched pairs of ultrasonic transducers with center frequencies of 0.5 and 1.0 MHz. The volumetric bone mineral density of the trabecular bone samples was measured by using micro-computed tomography. The bone mineral density exhibited strong correlations with both the speed of sound and the normalized broadband ultrasound attenuation measured by using the 0.5 and the 1.0 MHz transducers. The highest correlation was found between the bone mineral density and the normalized broadband ultrasound attenuation measured by using the 0.5 MHz ultrasonic transducers. The results suggest that the acoustic properties measured in the femur in vitro can be used as indices for the prediction of femoral bone mineral density.

Implementation of low-noise, wideband ultrasound receiver for high-frequency ultrasound imaging (고주파수 초음파 영상을 위한 저잡음·광대역 수신 시스템 구현)

  • Moon, Ju-Young;Lee, Junsu;Chang, Jin Ho
    • The Journal of the Acoustical Society of Korea
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    • v.36 no.4
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    • pp.238-246
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    • 2017
  • High frequency ultrasound imaging typically suffers from low sensitivity due to the small aperture of high frequency transducers and shallow imaging depth due to the frequency-dependent attenuation of ultrasound. These limitations should be overcome to obtain high-frequency, high- resolution ultrasound images. One practical solution to the problems is a high-performance signal receiver capable of detecting a very small signal and amplifying the signal with minimal electronic noise addition. This paper reports a recently developed low-noise, wideband ultrasound receiver for high-frequency, high-resolution ultrasound imaging. The developed receiver has an amplification gain of up to 73 dB and a variable amplification gain range of 48 dB over an operating frequency of 80 MHz. Also, it has an amplification gain flatness of ${\pm}1dB$. Due to these high performances, the developed receiver has a signal-to-noise ratio of at least 8.4 dB and a contrast-to-noise ratio of at least 3.7 dB higher than commercial receivers.

Estimation of Medical Ultrasound Attenuation using Adaptive Bandpass Filters (적응 대역필터를 이용한 의료 초음파 감쇠 예측)

  • Heo, Seo-Weon;Yi, Joon-Hwan;Kim, Hyung-Suk
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.47 no.5
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    • pp.43-51
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    • 2010
  • Attenuation coefficients of medical ultrasound not only reflect the pathological information of tissues scanned but also provide the quantitative information to compensate the decay of backscattered signals for other medical ultrasound parameters. Based on the frequency-selective attenuation property of human tissues, attenuation estimation methods in spectral domain have difficulties for real-time implementation due to the complexicity while estimation methods in time domain do not achieve the compensation for the diffraction effect effectively. In this paper, we propose the modified VSA method, which compensates the diffraction with reference phantom in time domain, using adaptive bandpass filters with decreasing center frequencies along depths. The adaptive bandpass filtering technique minimizes the distortion of relative echogenicity of wideband transmit pulses and maximizes the signal-to-noise ratio due to the random scattering, especially at deeper depths. Since the filtering center frequencies change according to the accumulated attenuation, the proposed algorithm improves estimation accuracy and precision comparing to the fixed filtering method. Computer simulation and experimental results using tissue-mimicking phantoms demonstrate that the distortion of relative echogenicity is decreased at deeper depths, and the accuracy of attenuation estimation is improved by 5.1% and the standard deviation is decreased by 46.9% for the entire scan depth.

Void Contents Evaluation of Composite Laminates by Ultrasonic Attenuation Measurements (초음파의 감쇠를 이용한 복합재료의 기공함량 평가)

  • 정현조
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.6
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    • pp.1535-1541
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    • 1994
  • The void content of carbon fiber reinforced composite laminates was determined by the ultrasonic nondestructive technique. The ultrasonic immersion, through-transmission method developed stresses the utilization of spectral analysis and frequency dependence of the attenuation due to porosity. The measured attenuation shows approximately linear behavior over the frequency range investigated. The linear relationship between the void content and the attenuation slop (d $\alpha$/df) is found to hold, but the constant of proportionality is quite different for samples with different pore morphology. The void volume fraction determined by the attenuation slope agreed very well with that obtained by the acid digestion analysis.

Dependences of Ultrasonic Parameters for Osteoporosis Diagnosis on Bone Mineral Density (골다공증 진단을 위한 초음파 변수의 골밀도에 대한 의존성)

  • Hwang, Kyo Seung;Kim, Yoon Mi;Park, Jong Chan;Choi, Min Joo;Lee, Kang Il
    • Journal of the Korean Society for Nondestructive Testing
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    • v.32 no.5
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    • pp.502-508
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    • 2012
  • Quantitative ultrasound technologies for osteoporosis diagnosis measure ultrasonic parameters such as speed of sound(SOS) and normalized broadband ultrasound attenuation(nBUA) in the calcaneus (heel bone). In the present study, the dependences of SOS and nBUA on bone mineral density in the proximal femur with high risk of fracture were investigated by using 20 trabecular bone samples extracted from bovine femurs. SOS and nBUA in the femoral trabecular bone samples were measured by using a transverse transmission method with one matched pair of ultrasonic transducers with a center frequency of 1.0 MHz. SOS and nBUA measured in the 20 trabecular bone samples exhibited high Pearson's correlation coefficients (r) of r = 0.83 and 0.72 with apparent bone density, respectively. The multiple regression analysis with SOS and nBUA as independent variables and apparent bone density as a dependent variable showed that the correlation coefficient r = 0.85 of the multiple linear regression model was higher than those of the simple linear regression model with either parameter SOS or nBUA as an independent variable. These high linear correlations between the ultrasonic parameters and the bone density suggest that the ultrasonic parameters measured in the femur can be useful for predicting the femoral bone mineral density.

Variations of Speed of Sound and Attenuation Coefficient with Porosity and Structure in Bone Mimics (뼈 모사체에서 다공율 및 구조에 대한 음속 및 감쇠계수의 변화)

  • Kim, Seong-Il;Choi, Min-Joo;Lee, Kang-Il
    • The Journal of the Acoustical Society of Korea
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    • v.29 no.6
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    • pp.388-394
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    • 2010
  • In the present study, polyacetal bone mimics with circular cylindrical pores were used to investigate variations of speed of sound and attenuation coefficient with porosity and microarchitecture in bone. The speed of sound and attenuation coefficient of the 6 bone mimics with porosities from 0 % to 65.9 % were measured by a through-transmission method in water, using a pair of broadband, unfocused transducers with a diameter of 12.7 mm and a center frequency of 1.0 MHz. Independently of the structural properties of the bone mimics, the speed of sound decreased almost linearly with the increasing porosity. The attenuation coefficient measured at 1.0 MHz exhibited linear or nonlinear correlations with the porosity, depending on the structural properties of the bone mimics. These results are consistent with those previously published by other researchers using bone samples and mimics, and advances our understanding of the relationships of the ultrasonic parameters for the diagnosis of osteoporosis with the bone density and microarchitecture in human bones.

Characteristics of High Frequency Ultrasonic Transducer Employing Polyvinylidene Fluoride and Detectability of Flaw in Cr-Ni Steel (PVDF 수침용 고주파수 초음파 탐촉자의 검출장과 Cr-Ni 강에서의 결함 검출능 측정)

  • Kim, Byoung-Geuk;Lee, S.S.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.17 no.1
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    • pp.23-30
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    • 1997
  • Recently high frequency ultrasonic transducers to employ polyvinylidene fluoride(PVDF) or polyvinylidene fluoride trifluoroethylene P(VDF-TrFE) have been used to detect small flaws in immersion testing. The detection field depending on the water path between the transducer and a specimen and the path in a tested specimen was measured using a PVDF transducer with nominal frequency 80MHz. Also, C-scan and B-scan were performed for the specimens made of Cr-Ni steel with the artificial flaws, the flat-bottom holes with diameter ranging from $50{\mu}m$ to $560{\mu}m$ at 12mm depth. As the result, the flaws with diameter larger than $280{\mu}m$ were detected, but the flaws with the ratio of diameter to wavelength smaller than about 0.48 were not detected. That the smaller flaws could not be detected was attributed to the attenuation of high frequency components in the steel specimens.

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Temperature and Frequency Dependences of Ultrasonic Properties in Commercial MC Nylon Polymers (상용 MC Nylon계 고분자 재료에서 초음파 특성의 온도 및 주파수 의존성)

  • Kim, Myung Deok;Kim, Yong Tae;Lee, Kang Il
    • Journal of the Korean Society for Nondestructive Testing
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    • v.32 no.5
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    • pp.509-517
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    • 2012
  • In the present study, temperature and frequency dependences of ultrasonic properties such as attenuation coefficient and phase velocity was investigated for six kinds of commercial MC-Nylon polymer samples. The ultrasonic properties of the samples were measured by using a pulse transmission method in water over a broadband frequency range of 2 to 8 MHz. Water temperature was varied from 10 to $60^{\circ}C$ with the $10^{\circ}C$ interval. The attenuation coefficients of the samples increased with the frequency and the exponent n of frequency dependence ranged within 1.16 to 1.44, slightly deviating from the linear dependence (n=1). The phase velocities of the samples exhibited negative dispersion, i.e., decreasing velocity with increasing frequency, except for ivory sample at $60^{\circ}C$. The frequency-dependent phase velocities of the samples showed the decreasing tendency with increasing temperature.

Effect of Cortical Bone on Acoustic Properties of Trabecular Bone in Bovine Femur In Vitro (생체 외 조건의 소 대퇴골에서 해면질골의 음향특성에 대한 피질골의 효과)

  • Hwang, Kyo Seung;Lee, Kang Il
    • The Journal of the Acoustical Society of Korea
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    • v.32 no.2
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    • pp.181-189
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    • 2013
  • The purpose of the present study is to investigate the effect of cortical bone on acoustic properties of trabecular bone, such as speed of sound (SOS) and normalized broadband ultrasound attenuation (nBUA), in bovine femur in vitro. Twelve trabecular bone samples and three cortical bone plates with thicknesses of 1.00, 1.47, and 2.00 mm were extracted from the proximal end of two bovine femurs. The correlations between acoustic properties and trabecular apparent bone density were also examined before and after attaching a cortical bone plate to the trabecular bone samples. SOS increased linearly with increasing thickness of the cortical plate attached to one side of ultrasonic incidence of the trabecular bone samples, whereas nBUA showed a nonlinear dependence on the thickness of the cortical plate. All the SOS (r = 0.95-0.97) and nBUA (r = 0.53-0.73) measurements with and without the cortical bone plate with various thicknesses were found to exhibit high correlations with the trabecular apparent bone density. These results imply that the acoustic properties measured in the femur with lateral cortical layers in vitro can be useful indices for the prediction of trabecular bone mineral density.

Dependencies of Group Velocity and Attenuation Coefficient on Structural Properties in Copper and Nickel Foams with an Open-Celled Structure as Trabecular-Bone-Mimicking Phantoms (해면질골 팬텀으로서 개포된 구조를 갖는 구리폼 및 니켈폼에서 구조적 특성에 대한 군속도 및 감쇠계수의 의존성)

  • Kim, Seong-Il;Lee, Kang-Il
    • The Journal of the Acoustical Society of Korea
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    • v.30 no.3
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    • pp.158-166
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    • 2011
  • In the present study, copper and nickel foams with an open-celled structure as trabecular-bone-mimicking phantoms were used to investigate the dependencies of group velocity and attenuation coefficient on structural properties such as trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp) in trabecular bone. The group velocity and attenuation coefficient of the copper and nickel foams were measured by a through-transmission method in water, using a pair of broadband, unfocused transducers with a diameter of 12.7 mm and a center frequency of 1.0 MHz. The separation of the Biot's fast and slow waves was consistently observed in the ultrasonic signals transmitted through the copper and nickel foams. The group velocities of the copper and nickel foams showed highly positive correlations with Tb.Th and Tb.Sp. The attenuation coefficient of the copper foam showed a highly negative correlation with Tb.Th and Tb.Sp, whereas that of the nickle foam showed a highly positive correlation with Tb.Th and Tb.Sp. These results advance our understanding of those previously reported by other researchers using trabecular bone samples or phantoms.