State and explain one advantage of the use of high-frequency ultrasound as compared with low-frequency ultrasound for medical diagnosis.
The absorption (attenuation) coefficient for ultrasound in muscle is 
. A parallel beam of ultrasound is passed through a muscle of thickness 
.
Calculate the ratio
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 that received at an earlier time.
