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Biophys J, November 1999, p. 2387-2399, Vol. 77, No. 5
*Laboratory of Biomedical Engineering,
A system-based model is proposed to describe and simulate
the ultrasound signal backscattered by red blood cells (RBCs). The model is that of a space-invariant linear system that takes into consideration important biological tissue stochastic scattering properties as well as the characteristics of the ultrasound system. The
formation of the ultrasound signal is described by a convolution integral involving a transducer transfer function, a scatterer prototype function, and a function representing the spatial arrangement of the scatterers. The RBCs are modeled as nonaggregating spherical scatterers, and the spatial distribution of the RBCs is determined using the Percus-Yevick packing factor. Computer simulations of the
model are used to study the power backscattered by RBCs as a function
of the hematocrit, the volume of the scatterers, and the frequency of
the incident wave (2-500 MHz). Good agreement is obtained between the
simulations and theoretical and experimental data for both Rayleigh and
non-Rayleigh scattering conditions. In addition to these results, the
renewal process theory is proposed to model the spatial arrangement of
the scatterers. The study demonstrates that the system-based model is
capable of accurately predicting important characteristics of the
ultrasound signal backscattered by blood. The model is simple and
flexible, and it appears to be superior to previous one- and
two-dimensional simulation studies.
Biophys J, November 1999, p. 2387-2399, Vol. 77, No. 5
© 1999 by the Biophysical Society 0006-3495/99/11/2387/13 $2.00
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