A dedicated ultrasonic scanner for acquiring RF echoes backscattered from the trabecular bone was developed. The design of device is based on the goal of minimizing of custom electronics and computations executed solely on the main computer processor and the graphics card. The electronic encoder-digitizer module executing all of the transmission and reception functions is based on a single low-cost field programmable gate array (FPGA). The scanner is equipped with a mechanical sector-scan probe with a concave transducer with 50 mm focal length, center frequency of 1.5 MHz and 60% bandwidth at -6 dB. The example of femoral neck bone examination shows that the scanner can provide ultrasonic data from deeply located bones with the ultrasound penetrating the trabecular bone up to a depth of 20 mm. It is also shown that the RF echo data acquired with the scanner allow for the estimation of attenuation coefficient and frequency dependence of backscattering coefficient of trabecular bone. The values of the calculated parameters are in the range of corresponding in vitro data from the literature but their variation is relatively high.

The paper describes the investigations intended to compare the results of experimental measurements of backscattering properties of the trabecular bone with the results of computer simulations. Ultrasonic RF echoes were collected using two bone scanners operating at 0.58 and 1.3 MHz. The simulations of the backscattered RF echoes were performed using the scattering model of the trabecular bone that consisted of cylindrical and spherical elements uniformly distributed in water-like medium. For each measured or simulated RF backscatter the statistical properties of the signal envelope were determined. Experimental results suggest deviations of the backscattering properties from the Rayleigh distribution. The results of simulation suggest that deviation from Rayleigh distribution depends on the variation of trabeculae diameters and the number of thin trabeculae. Experimentally determined deviations corresponded well to the deviations calculated from simulated echoes assuming trabeculae thickness variation equaled to the earlier published histomorphometric study results.

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The ultrasonic scanner dedicated for acquiring the RF echoes, backscattered from the trabecular bone, was developed. The device is based on the concept of minimizing of electronics and computations executed solely in the main computer processor and the graphics card. The electronic module of encoder-digitizer -executing all the transmission and reception functions -is based on a single low-cost FPGA chip. The scanner is equipped with the mechanical sector scan probe with a concave transducer with 50 mm focal length, center frequency of 1.5 MHz and 60 % bandwidth at -6 dB. The example of femoral neck bone examination shows that the scanner can provide ultrasonic data from deeply located bones with the ultrasound penetrating the trabecular bone up to the depth of 20 mm. It was also presented that the RF echo-data acquired with the scanner allow for the estimation of sound attenuation in trabecular bone.

The presented investigations were intended to compare the experimental results obtained from the heel bones in vivo with the results of simulations. Ultrasonic RF echoes were collected using two bone scanners operating at 0.58 MHz and 1.3 MHz. The simulations of the backscattered RF echoes were performed using the scattering model of the trabecular bone that consisted of cylindrical and spherical elements uniformly distributed in water. For each measured or simulated RF backscatter statistical properties of the signal envelope was determined. Experimental results suggest deviations from the Rayleigh distribution. Simulation results suggest that deviations from Rayleigh distribution depend on the variation of trabeculae diameters and the number of thin trabeculae. Experimentally determined deviations corresponded well with the deviations calculated from simulated echoes assuming trabeculae thickness variation equal to published histomorphometric study results.