Photo-acoustic Excitation and Optical Detection of Fundamental Flexural Guided Wave in Coated Bone Phantoms

Moilanen, Petro; Zhao, Zuomin; Karppinen, Pasi; Karppinen, Timo; Kilappa, Vantte; Pirhonen, Jalmari; Myllylä, Risto; Hæggström, Edward; Timonen, J.

doi:10.1016/j.ultrasmedbio.2013.10.018

Cited by 26 publications

(21 citation statements)

References 49 publications

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“…[3][4][5] Accuracy of estimates for bone characteristics depends on the chosen model for ultrasound propagation in the cortical bone (which represents the "forward problem") and on its ability to account for the complexity of the waveguide, including not only the elastic anisotropy, the tubular shape of bone and the presence of soft tissues, but also a variable thickness, irregular geometry, inhomogeneity, and absorption, for example. In previous investigations, more or less complex waveguide models, such as free plate 5 and tube models, 3,4,11 or bilayer models, [12][13][14] were applied and found to conform fairly well to experimental dispersion curves of guided modes in bone mimicking phantoms 3,5,12,14 and in ex vivo bone specimens. [3][4][5]13 On the other hand, more complex models involving more physical parameters would make the solution of the inverse problem more difficult to find.…”

Section: -10mentioning

confidence: 78%

“…In particular, earlier studies by Moilanen et al suggest that, at low ultrasound frequencies (<0.4 MHz), the effects of bone curvature 3 and coating 14,19 must be accounted for by the model, so as to properly evaluate the characteristics (such as wall thickness) of the solid waveguide. Sensitivity to such geometrical details with decreasing frequency could be true and explained by wavelength, which then becomes longer, and absorption, which then becomes weaker.…”

Section: Ultrasonic Methodsmentioning

confidence: 99%

“…14,15 All tubes had a length of 120 mm and a transverse circular cross-section with an external radius of curvature of 8 mm. Five wall thicknesses from 1 to 5 mm [known to an accuracy of 60.05 mm (Ref.…”

Section: Samplesmentioning

confidence: 99%

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A free plate model can predict guided modes propagating in tubular bone-mimicking phantoms

Minonzio

Foiret

Moilanen

et al. 2014

The Journal of the Acoustical Society of America

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The goal of this work was to show that a non-absorbing free plate model can predict with a reasonable accuracy guided modes measured in bone-mimicking phantoms that have circular cross-section. Experiments were carried out on uncoated and coated phantoms using a clinical axial transmission setup. Adjustment of the plate model to the experimental data yielded estimates for the waveguide characteristics (thickness, bulk wave velocities). Fair agreement was achieved over a frequency range of 0.4 to 1.6 MHz. A lower accuracy observed for the thinnest bone-mimicking phantoms was caused by limitations in the wave number measurements rather than by the model itself.

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Section: -10mentioning

confidence: 78%

Section: Ultrasonic Methodsmentioning

confidence: 99%

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A free plate model can predict guided modes propagating in tubular bone-mimicking phantoms

Minonzio

Foiret

Moilanen

et al. 2014

The Journal of the Acoustical Society of America

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“…50,51 This approach has several disadvantages, which limit their potential use. First, in real situation, the bones are wet while inside the body.…”

Section: Discussionmentioning

confidence: 99%

Multi-layered tissue head phantoms for noninvasive optical diagnostics

Wróbel

Попов

Bykov

et al. 2015

J. Innov. Opt. Health Sci.

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Extensive research in the area of optical sensing for medical diagnostics requires development of tissue phantoms with optical properties similar to those of living human tissues. Development and improvement of in vivo optical measurement systems requires the use of stable tissue phantoms with known characteristics, which are mainly used for calibration of such systems and testing their performance over time. Optical and mechanical properties of phantoms depend on their purpose. Nevertheless, they must accurately simulate speci¯c tissues they are supposed to mimic. Many tissues and organs including head possess a multi-layered structure, with speci¯c optical properties of each layer. However, such a structure is not always addressed in the presentday phantoms. In this paper, we focus on the development of a plain-parallel multi-layered phantom with optical properties (reduced scattering coe±cient 0 s and absorption coe±cient a ) corresponding to the human head layers, such as skin, skull, and gray and white matter of the brain tissue. The phantom is intended for use in noninvasive di®use near-infrared spectroscopy (NIRS) of human brain. Optical parameters of the fabricated phantoms are reconstructed using spectrophotometry and inverse adding-doubling calculation method. The results show that polyvinyl chloride-plastisol (PVCP) and zinc oxide (ZnO) nanoparticles are suitable materials for fabrication of tissue mimicking phantoms with controlled scattering properties. Good matching

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“…In vivo assessment of FFGW through soft tissue, which always covers the bone, is, however, challenging (Moilanen et al, 2008). This is due to the low FFGW amplitude on top of the soft tissue as well as to propagating ultrasonic modes in that tissue, which interfere with FFGW (Moilanen et al, 2014). This problem of FFGW detection can be alleviated on the receiver side by group-velocity filtering (Moilanen et al, 2006) and 2D-Fourier-transform analysis (2D-FFT) (Alleyne and Cawley, 1991), or by alternative techniques reported by other research groups, such as singular value decomposition (Minonzio et al, 2010), Radon transform (Tran et al, 2013) or various methods based on time-frequency transformation (Cohen, 1989;Protopappas et al, 2006;Xu et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Tailoring the excitation of fundamental flexural guide waves in coated bone by phase-delayed array: Two-dimensional simulations

Kilappa

Moilanen

Salmi

et al. 2015

The Journal of the Acoustical Society of America

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The fundamental flexural guided wave (FFGW) enables ultrasonic assessment of cortical bone thickness. In vivo, it is challenging to detect this mode, as its power ratio with respect to disturbing ultrasound is reduced by soft tissue covering the bone. A phase-delayed ultrasound source is proposed to tailor the FFGW excitation in order to improve its power ratio. This situation is analyzed by 2D finite-element simulations. The soft tissue coating (7-mm thick) was simulated as a fluid covering an elastic plate (bone, 2-6 mm thick). A six-element array of emitters on top of the coating was excited by 50-kHz tone bursts so that each emitter was appropriately delayed from the previous one. Response was recorded by an array of receivers on top of the coating, 20-50 mm away from the closest emitter. Simulations predicted that such tailored/phase-delayed excitations should improve the power ratio of FFGW by 23 ± 5 dB, independent of the number of emitters (N). On the other hand, the FFGW magnitude should increase by 5.8 ± 0.5 dB for each doubling of N. This suggests that mode tailoring based on phase-delayed excitation may play a key role in the development of an in vivo FFGW assessment.

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Photo-acoustic Excitation and Optical Detection of Fundamental Flexural Guided Wave in Coated Bone Phantoms

Cited by 26 publications

References 49 publications

A free plate model can predict guided modes propagating in tubular bone-mimicking phantoms

A free plate model can predict guided modes propagating in tubular bone-mimicking phantoms

Multi-layered tissue head phantoms for noninvasive optical diagnostics

Tailoring the excitation of fundamental flexural guide waves in coated bone by phase-delayed array: Two-dimensional simulations

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