Author Question: Explain how the pulse-echo technique works for medical imaging. What will be an ideal ... (Read 94 times)

tiffannnnyyyyyy · **on:** Jul 29, 2018

Explain how the pulse-echo technique works for medical imaging.

What will be an ideal response?

Question 2

By how many newtons does the weight of a 100-kg person change when he goes from sea level to an altitude of 5000 m? (The mean radius of the Earth is 6.38 106 m.)

A)

0.6 N

B)

1.6 N

C)

2.6 N

D)

3.6 N

E)

5.2 N

brittrenee · **Reply #1 on:** Jul 29, 2018

Answer to Question 1

A brief pulse of ultrasound is emitted by a transducer that transforms an electrical pulse into a sound-wave pulse. Part of the pulse is reflected as echoes at each interface in the body, and most of the pulse continues on. The detection of reflected pulses by the same transducer can then be displayed on the screen of a monitor. The time elapsed from when the pulse is emitted to when each reflection is received is proportional to the distance to the reflecting surface. The strength of a reflected pulse depends mainly on the difference in density of the two materials on either side of the interface and can be displayed as a pulse or as a dot. Each dot can be represented as a point whose position is given by the time delay and whose brightness depends on the strength of the echo. A two-dimensional image can then be formed out of these dots from a series of scans.

Answer to Question 2

B