scholarly journals A 3D-printed passive ultrasound phase-interference compensator for reduced wave degradation in cancellous bone – an experimental study in replica models

2018 ◽  
Vol 9 ◽  
pp. 204173141876641 ◽  
Author(s):  
Christian M Langton ◽  
Saeed M AlQahtani ◽  
Marie-Luise Wille
Keyword(s):  
Transit Time ◽  
Cancellous Bone ◽  
Broadband Ultrasound Attenuation ◽  
Quantitative Measure ◽  
Ultrasound Transducer ◽  
Single Element ◽  
Ultrasound Wave ◽  
Additional Material ◽  
Phase Interference ◽  
3D Printed

The current ‘active’ solution to overcome the impediment of ultrasound wave degradation associated with transit-time variation in complex tissue structures, such as the skull, is to vary the transmission delay of ultrasound pulses from individual transducer elements. This article considers a novel ‘passive’ solution in which constant transit time is achieved by propagating through an additional material layer positioned between the ultrasound transducer and the test sample. To test the concept, replica models based on four cancellous bone natural tissue samples and their corresponding passive ultrasound phase-interference compensator were 3D-printed. Normalised broadband ultrasound attenuation was used as a quantitative measure of wave degradation, performed in transmission mode at a frequency of 1 MHz and yielding a reduction ranging from 57% to 74% when the ultrasound phase-interference compensator was incorporated. It is suggested that the passive compensator offers a broad utility and, hence, it may be applied to any ultrasound transducer, of any complexity (single element or array), frequency and dimension.

scholarly journals The dependence of broadband ultrasound attenuation on phase interference in thin plates of variable thickness and curvature: a comparison of experimental measurement and computer simulation

2018 ◽  
Vol 232 (5) ◽  
pp. 468-478 ◽  
Author(s):  
Ali Hamed Alomari ◽  
Marie-Luise Wille ◽  
Christian M Langton
Keyword(s):  
Computer Simulation ◽  
Cancellous Bone ◽  
Variable Thickness ◽  
Broadband Ultrasound Attenuation ◽  
Constant Thickness ◽  
Single Element ◽  
Mineral Density ◽  
Attenuation Measurement ◽  
Ultrasound Attenuation ◽  
Phase Interference

The measurement of broadband ultrasound attenuation describes the linear increase in ultrasound attenuation with frequency (dB/MHz); this is generally performed at the calcaneus, consisting of a high proportion of metabolically active cancellous bone. Although broadband ultrasound attenuation is not routinely implemented within clinical management since it cannot provide a reliable estimation of bone mineral density and hence clinical definition of osteopenia and osteoporosis, it offers a reliable means to predict osteoporotic fracture risk. One of the potential factors that can influence the accuracy of broadband ultrasound attenuation measurement is the effect of cortical end plates. This study aimed to explore this, performing a comparison of experimental study and computer simulation prediction. A total of three categories of thin discs were three-dimensional (3D) printed to replicate cortical shells of (1) variable constant thickness (planar), (2) variable constant thickness (curved), and (3) variable thickness. A through-transmission technique was used, where two single-element, unfocused, 1 MHz broadband transducers, as utilised clinically, were positioned coaxially in a cylindrical holder and immersed in water. Both quantitative and qualitative analyses demonstrated that broadband ultrasound attenuation measurements of the ‘planar’ and ‘curved’ discs were not statistically different (p-values > 0.01). A cyclic relationship between broadband ultrasound attenuation and disc thickness was observed; this was replicated within a computer simulation of phase interference created by a double-reflection echo within each disc (R2 = 97.0%). Variable-thickness discs provided broadband ultrasound attenuation measurements ranging between 31.6 ± 0.1 and 40.60 ± 0.1 dB/MHz. Again applying the double-reflection echo simulation, a high level of agreement between experimental and simulation was recorded (R2 = 93.4%). This study indicates that the cortical end plate can significantly affect the broadband ultrasound attenuation measurement of cancellous bone as a result of phase interference and, therefore, warrants further investigation to minimise its effect on clinical assessment.

scholarly journals Reconstruction of Severe Acetabular Bone Defect with 3D Printed Ti6Al4V Augment: A Finite Element Study

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Jun Fu ◽  
Ming Ni ◽  
Jiying Chen ◽  
Xiang Li ◽  
Wei Chai ◽  
...  
Keyword(s):  
Finite Element ◽  
Yield Strength ◽  
Bone Defect ◽  
Cancellous Bone ◽  
Acetabular Bone ◽  
Fea Model ◽  
Acetabular Bone Defect ◽  
3D Printed ◽  
Von Mises ◽  
Von Mises Stresses

Purpose. The purpose of this study was to establish the finite element analysis (FEA) model of acetabular bone defect reconstructed by 3D printed Ti6Al4V augment and TM augment and further to analyze the stress distribution and clinical safety of augments, screws, and bones.Methods. The FEA model of acetabular bone defect reconstructed by 3D printed Ti6Al4V augment was established by the CT data of a patient with Paprosky IIIA defect. The von Mises stresses of augments, screws, and bones were analyzed by a single-legged stance loading applied in 3 increments (500 N, 2000 N, and 3000 N).Results. The peak von Mises stresses under the maximal loading in the 3D printed augments, screws, and cortical bone were less than the yield strength of the corresponding component. However, the peak stress in the bone was greater than the yield strength of cancellous bone under walking or jogging loading. And under the same loading, the peak compressive and shear stresses in bone contact with TM augment were larger than these with 3D printed augment.Conclusions. The FEA results show that all the components will be intact under single-legged standing. However, partial cancellous bone contacted with 3D printed augment and screws will lose efficacy under walking or jogging load. So we recommend that patients can stand under full bearing, but can not walk or jog immediately after surgery.

scholarly journals Porous polylactic acid scaffolds for bone regeneration: A study of additively manufactured triply periodic minimal surfaces and their osteogenic potential

2020 ◽  
Vol 11 ◽  
pp. 204173142095654
Author(s):  
Anna Diez-Escudero ◽  
Hugo Harlin ◽  
Per Isaksson ◽  
Cecilia Persson
Keyword(s):  
Polylactic Acid ◽  
Cancellous Bone ◽  
Minimal Surfaces ◽  
Pore Distribution ◽  
Osteogenic Potential ◽  
Osteoblastic Cell ◽  
Triply Periodic Minimal Surfaces ◽  
Triply Periodic ◽  
3D Printed ◽  
Grade Material

Three different triply periodic minimal surfaces (TPMS) with three levels of porosity within those of cancellous bone were investigated as potential bone scaffolds. TPMS have emerged as potential designs to resemble the complex mechanical and mass transport properties of bone. Diamond, Schwarz, and Gyroid structures were 3D printed in polylactic acid, a resorbable medical grade material. The 3D printed structures were investigated for printing feasibility, and assessed by morphometric studies. Mechanical properties and permeability investigations resulted in similar values to cancellous bone. The morphometric analyses showed three different patterns of pore distribution: mono-, bi-, and multimodal pores. Subsequently, biological activity investigated with pre-osteoblastic cell lines showed no signs of cytotoxicity, and the scaffolds supported cell proliferation up to 3 weeks. Cell differentiation investigated by alkaline phosphatase showed an improvement for higher porosities and multimodal pore distributions, suggesting a higher dependency on pore distribution and size than the level of interconnectivity.

scholarly journals Tortuosity and the Averaging of Microvelocity Fields in Poroelasticity

2013 ◽  
Vol 80 (2) ◽  
Author(s):  
M. F. Souzanchi ◽  
L. Cardoso ◽  
S. C. Cowin
Keyword(s):  
Porous Media ◽  
Kinetic Energy ◽  
Energy Loss ◽  
Cancellous Bone ◽  
Quantitative Measure ◽  
Pore Fluid ◽  
Fluid Viscosity ◽  
Anisotropic Porous Media ◽  
Pore Architecture ◽  
Kinetic Energy Loss

The relationship between the macro- and microvelocity fields in a poroelastic representative volume element (RVE) has not being fully investigated. This relationship is considered to be a function of the tortuosity: a quantitative measure of the effect of the deviation of the pore fluid streamlines from straight (not tortuous) paths in fluid-saturated porous media. There are different expressions for tortuosity based on the deviation from straight pores, harmonic wave excitation, or from a kinetic energy loss analysis. The objective of the work presented is to determine the best expression for tortuosity of a multiply interconnected open pore architecture in an anisotropic porous media. The procedures for averaging the pore microvelocity over the RVE of poroelastic media by Coussy and by Biot were reviewed as part of this study, and the significant connection between these two procedures was established. Success was achieved in identifying the Coussy kinetic energy loss in the pore fluid approach as the most attractive expression for the tortuosity of porous media based on pore fluid viscosity, porosity, and the pore architecture. The fabric tensor, a 3D measure of the architecture of pore structure, was introduced in the expression of the tortuosity tensor for anisotropic porous media. Practical considerations for the measurement of the key parameters in the models of Coussy and Biot are discussed. In this study, we used cancellous bone as an example of interconnected pores and as a motivator for this study, but the results achieved are much more general and have a far broader application than just to cancellous bone.

P1D-4 Fast Rotating Single Element Ultrasound Transducer for Image-Guided Thermal

2006 ◽  
Author(s):  
G. Fleury ◽  
D. Cathignol ◽  
G. Bouchoux ◽  
R. Berriet ◽  
C. Lafon
Keyword(s):  
Ultrasound Transducer ◽  
Single Element ◽  
Image Guided ◽  
Fast Rotating

scholarly journals Resonating Shell: A Spherical-Omnidirectional Ultrasound Transducer for Underwater Sensor Networks

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 757 ◽  
Author(s):  
Sina Sadeghpour ◽  
Sebastian Meyers ◽  
Jean-Pierre Kruth ◽  
Jozef Vleugels ◽  
Michael Kraft ◽  
...  
Keyword(s):  
Power Consumption ◽  
Actuation Voltage ◽  
Center Frequency ◽  
Ultrasound Transducer ◽  
Ultrasound Wave ◽  
Outer Diameter ◽  
Underwater Sensor Networks ◽  
Layer By Layer ◽  
Water Tank ◽  
Manufacturing Method

This paper presents the design and fabrication process of a spherical-omnidirectional ultrasound transducer for underwater sensor network applications. The transducer is based on the vibration of two hemispheres with a thickness of 1 mm and an outer diameter of 10 mm, which are actuated by two piezoelectric ring elements. Since the ultrasound wave is generated by the vibration of the two hemispheres, a matching layer is not required. Silicon Carbide (SiC) is used as the material of the hemispherical shells of the transducer. The shells were fabricated by laser sintering as an additive manufacturing method, in which the hemispheres were built layer by layer from a powder bed. All manufactured transducers with an outer dimension of 10 × 14.2 mm and a center frequency of 155 kHz were measured in a water tank by a hydrophone or in mutual communication. The circumferential source level was measured to vary less than 5dB. The power consumption and the insertion loss of the transducer, ranging from 100 μ W to 2.4 mW and 21.2 dB, respectively, along with all other measurements, prove that the transducer can transmit and receive ultrasound waves omnidirectionally at tens of centimeters intervals with a decent power consumption and low actuation voltage.

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