(a)[6]
Explain the basic principles of using ultrasound to gather diagnostic information about structures inside the body.
(b)[2]
State and explain one advantage of high frequency ultrasound over low frequency ultrasound when used for medical diagnosis.
(c(i))[3]
The absorption (attenuation) coefficient for ultrasound in muscle is $23\,\text{m}^{-1}$. A parallel beam of ultrasound is sent through muscle with thickness $6.4\,\text{cm}$. Calculate the ratio $\frac{\text{intensity of transmitted beam}}{\text{intensity of incident beam}}$.
(c(ii))[2]
An ultrasound transmitter emits a pulse. Suggest why, when the signal from the pulse is processed, any signal received later at the detector is usually amplified more than a signal received earlier.