medical

Question 1

Explain how A scans can be used to measure the thickness of a patients eye

Answer 1

• A scans use single transducers to emit a pulse of ultrasound
• measure time taken for echo to return to boundary
• d= st/2
• distance from front to back = total thickness

Question 2

what are some positives of ultrasound?

Answer 2

• non ionising
• non invasive
• cheap and portable

Question 3

What are some negatives of ultrasound?

Answer 3

• limited penetration, deep structures in the body can’t be reached
• low resolution

Question 4

Define doppler effect

Answer 4

Change in frequency (or wavelength) of a wave in relation to an observer who is moving relative to the wave source

Question 5

How can the doppler effect be used to measure blood flow velocity?

Answer 5

• Ultrasound waves are reflected off of moving blood cells
• the frequency shift between the transmitted and recieved signals is used to calculate the velocity of blood flow