Strelitzki R, Evans J A, Clarke A J
Centre for Bone and Body Composition Research, University of Leeds, UK.
Osteoporos Int. 1997;7(4):370-5. doi: 10.1007/BF01623780.
Ultrasonic propagation in bone has been investigated using the Leeds Ultrasonic Bone Phantom Material. Phantoms were produced with different porosities in the range of 45-83% and pore sizes of 1.3 and 0.6 mm. The phase velocity at 600 kHz was found to follow a second-order polynomial as a function of porosity. Phase velocity values between 1545 and 2211 m s-1 were measured and found to be largely independent of pore size for a given porosity. The slope of the phase velocity as a function of frequency (dispersion) decreases with increasing porosity. The values obtained from samples having different pore sizes were also similar. The attenuation coefficient and normalized broadband ultrasonic attenuation (nBUA) reached a maximum at about 50%. The normalized attenuation ranged from 6 to 25 dB cm-1 over the porosity range available and consistently showed higher values for the larger pore size. Similarly, the nBUA values were found to be between 14 and 53 dB MHz-1 cm-1, with the values for the larger pore size being roughly 10 dB MHz-1 cm-1 greater than those for the smaller pore size. These findings demonstrate that the Leeds phantom can be used to investigate the effect of structural changes in bone and to aid the understanding of quantitative ultrasound. The results support the assumption that the velocity in trabecular bone is not dependent on pore size but is influenced by the mechanical properties of the bone's constituents and the overall framework, whereas the attenuation and BUA are also influenced by structure.
利用利兹超声骨模拟材料对超声波在骨中的传播进行了研究。制作了孔隙率在45%-83%范围内、孔径分别为1.3毫米和0.6毫米的模拟体。发现600千赫兹时的相速度随孔隙率呈二阶多项式变化。测量得到的相速度值在1545至2211米/秒之间，且发现对于给定的孔隙率，相速度在很大程度上与孔径无关。相速度随频率变化（频散）的斜率随孔隙率增加而减小。从具有不同孔径的样品中获得的值也相似。衰减系数和归一化宽带超声衰减（nBUA）在约50%时达到最大值。在可用的孔隙率范围内，归一化衰减范围为6至25分贝/厘米，并且对于较大孔径始终显示出更高的值。同样，nBUA值在14至53分贝/兆赫·厘米之间，较大孔径的值比较小孔径的值大约大10分贝/兆赫·厘米。这些发现表明，利兹模拟体可用于研究骨结构变化的影响，并有助于理解定量超声。结果支持这样的假设，即小梁骨中的速度不依赖于孔径，而是受骨成分的力学性能和整体结构的影响，而衰减和BUA也受结构影响。
