Table 2.
Estimates from Eq. 2 for the reduction of acoustical radiation pressure at the surface for the bulk model PSRb relative to a tissue-air interface PRSa for transmission of ultrasound into the lung with a lung density of ρlung = 400 kgm−3 and speeds of sound clung from values given by Dunn (1986). The density and speed of sound for the tissue side of the blood-air barrier were taken to be ρtis = 1050 kg m−3 and ctis = 1550 m s−1, respectively. The intensity transmission coefficient (ITC) is also given to indicate the potential energy penetrating into the interior of the lung.
| Frequency MHz | clung m s−1 | ρlung clung krayl | ctis/clung | Z | PSRb/PRSa | ITC |
|---|---|---|---|---|---|---|
| 1.0 | 644 | 258 | 2.4 | 6.3 | 0.20 | 0.47 |
| 1.5 | 712 | 285 | 2.2 | 5.7 | 0.19 | 0.51 |
| 3.0 | 916 | 366 | 1.7 | 4.4 | 0.19 | 0.60 |
| 4.5 | 1126 | 450 | 1.4 | 3.6 | 0.19 | 0.68 |
| 5.0 | 1196 | 478 | 1.3 | 3.4 | 0.19 | 0.70 |
| 7.0 | 1472 | 589 | 1.1 | 2.8 | 0.20 | 0.78 |
| 7.5 | 1541 | 616 | 1.0 | 2.6 | 0.20 | 0.80 |