Table 3.
Ultrasound properties at 22°C for the components of the ultrasound elastography phantom
| Attenuation coefficient
|
|||||
|---|---|---|---|---|---|
| Tissue-mimicking material | Propagation speed (m/s) | Density (g/ml) | α0 (dB cm−1MHz−n) | n | Atten. coeff. ÷ freq. at 7.4 MHz (dB/cm/MHz) |
| Fibroadenoma | 1557 ± 1 | 1.01 ± 0.005 | 0.09 ± 0.03 | 1.57 ± 0.17 | 0.28 ± 0.02 |
| Cancer | 1533 ± 1 | 0.99 ± 0.005 | 0.13 ± 0.03 | 1.55 ± 0.12 | 0.39 ± 0.02 |
| Glandular | 1511.5 ± 1.3* | 0.97 ± 0.005 | 0.22 ± 0.02† | 1.31 ± 0.05† | 0.41 ± 0.02† |
| Fat sphere | 1491 ± 1 | 0.95 ± 0.005 | 0.36 ± 0.06 | 1.18 ± 0.08 | 0.52 ± 0.02 |
| Subcutaneous fat | 1492 ± 1 | 0.95 ± 0.005 | 0.35 ± 0.06 | 1.16 ± 0.08 | 0.48 ± 0.02 |
The attenuation coefficients, α, have been fitted to the relation α = α0 f n where α0 and n are fitting constants; the uncertainties in α0 and n account for an instrumental uncertainty in measurements of each attenuation coefficient of 0.15 dB/cm (Bevington 1969). The attenuation coefficient ÷ frequency at 7.4 MHz is also shown for reference because the ultrasound elastograms in Figs. 10–18 were generated using ultrasound near that frequency.
= “uncertainty” is the standard deviation for values for all four layers of the glandular region;
= result using attenuation coefficient values for all four layers of the glandular region; atten. coeff. = attenuation coefficiencies; freq. = frequency.