(a)[6]
Explain the basic principles that underlie the use of ultrasound to obtain diagnostic information about internal body structures.
(b)[3]
A parallel beam of ultrasound enters a muscle layer of thickness $4.6\,\text{cm}$ with intensity $I_0$, as shown in Fig. 4.1. Just before the beam leaves the muscle, its intensity is $I_T$. The ratio $\frac{I_0}{I_T}$ is measured to be $2.9$. Calculate the linear attenuation (absorption) coefficient $\mu$ of the ultrasound in the muscle layer.