Dependencies of the Attenuation Coefficient on the Frequency and the Trabecular Thickness in Trabecular-bone-mimicking Phantoms: Application of a Scattering Model

초록

The present study aims to provide insight into the dependencies of the attenuation coefficient on the frequency and the trabecular thickness in trabecular bone by using trabecular-bone-mimicking phantoms consisting of nickel foams immersed in water. The frequency-dependent attenuation coefficients were measured over a frequency range from 0.8 to 1.2 MHz. The present study also adopted a scattering model, in which the scattering coefficient is proportional to the mean velocity fluctuation, to predict the experimental measurements in the phantoms. The attenuation coefficients for the phantoms appeared to increase approximately linearly with the frequency from 0.8 to 1.2 MHz, consistent with the behavior in trabecular bone. The specific attenuation coefficient for the phantoms was found to vary nonlinearly with the trabecular thickness from 52 to 215 mu m. Despite the limitation that the scattering model does not account for absorption, it successfully predicted the experimental measurements, suggesting that scattering is the principal mechanism responsible for the attenuation in these phantoms.

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