A Method for the Measurement of Acoustic Impedance and Speed of Sound in a Small Region of Bone using a Fused Quartz Rod as a Transmission Line

Abstract

Precise correction for γ-ray attenuation in skull bone has been a significant problem in obtaining quantitative single photon emission computed tomography (SPECT) images. The correction for γ-ray attenuation is approximately proportional to the density and thickness of the bone under investigation. If the acoustic impedance and the speed of sound in bone are measurable using ultrasonic techniques, then the density and thickness of the bone sample can be calculated. Whole bone usually consists of three layers, and each layer has a different ultrasonic character. Thus, the speed of sound must be measured in a small section of each layer in order to determine the overall density of whole bone. It is important to measure the attenuation constant in order to determine the appropriate level for the ultrasonic input signal. We have developed a method for measuring the acoustic impedance, speed of sound, and attenuation constant in a small region of a bone sample using a fused quartz rod as a transmission line. In the present study, we obtained the following results: impedance of compact bone; 5.30(±0.40)×106 kg/(m2s), speed of sound; 3780±250 m/s, and attenuation constant; 2.70±0.50 Np/m. These results were used to obtain the densities of compact bone, spongy bone and bone marrow in a bovine bone sample and as well as the density of pig skull bone, which were found to be 1.40±0.30 g/cm3, 1.19±0.50 g/cm3, 0.90±0.30 g/cm3 and 1.26±0.30 g/cm3, respectively. Using a thin solid transmission line, the proposed method makes it possible to determine the density of a small region of a bone sample. It is expected that the proposed method, which is based on ultrasonic measurement, will be useful for application in brain SPECT.

Accurate in vitro identification of fracture onset in bones: Failure mechanism of the proximal human femur

“…Acoustic emissions (AE) were applied to bone (Guyer and Dauskardt, 2004;Van Toen et al, 2012). However, identification of the point of fracture initiation based on two AE-detectors is intrinsically impossible when the structure is inhomogeneous and anisotropic (Hatakeyama et al, 2000;Reilly et al, 2005). Adhesive sensors such as grid-based crack-propagation (Miles and Tanner, 1992), or foil crack gauges made of constantan sheet (Krak-Gauge, Rumul, Neuhausen, CH) or a graphite layer (Hatakeyama et al, 2000) can be applied only on flat or single-curvature surfaces.…”

A Novel Method for Determining the Time and Location of Abrupt Fracture Initiation in Bones

“…While acoustic emissions are very effective in detecting fracture onset, they are less accurate in determining the instant when the structure has failed. Also, spatial accuracy with acoustic emissions is severely limited with the inhomogeneous and irregular structure of bone [22].…”

Production of nanoparticles from natural hydroxylapatite by laser ablation

“…On the other hand, stress confinement condition is fulfilled when the energy is deposited in the irradiated volume more rapidly than it can be dissipated through collective molecular motion according to τ p ≪ t sc , which can lead to material fracture into more or less chunks [ 21 ]. As the use of CW laser is dominated by thermal regime, both conditions can be estimated in our work in the case of pulsed laser when thermal diffusivity ( ) and the speed of sound ( v s = 1801 m/s) for spongy bone [ 22 , 23 ] are assumed valid for fish bones. Calculations for the used laser beam diameter ( φ = 0.14 mm) confirm that thermal confinement condition is fulfilled for laser pulse durations in our experiments.…”