P4 - Ultrasound Treatments & Scans

Question 1

How are compressions and rarefractions made?

Answer 1

• Sound waves squash up and stretch out the arrangement of particles in material they pass through, making compressions and rarefractions.

Question 2

What are compressions?

Answer 2

Compressions are parts of a wave under high pressure

Question 3

What are rarefractions?

Answer 3

Rarefractions are areas under low pressure ( fewer particles ).

Question 4

What is the wavelength?

Answer 4

Wavelength is the full cycle of a wave, e.g. from crest to crest, or from compression to compression.

Question 5

What is frequency & how is it measured?

Answer 5

Frequency is how many complete waves there are per second ( passing a certain point ). Frequency is measured in hertz. 1 Hz is 1 complete wave per second.

Question 6

What is amplitude?

Answer 6

Amplitude is how much energy the wave is carrying, or how loud the sound is.

Question 7

How can you see the amplitude of a sound?

Answer 7

You can see the amplitude of a sound on a CRO ( Oscilloscope ).
- CRO displays show sounds as transverse waves so you can see what is going on.

Question 8

Where do you measure the amplitude from?

Answer 8

You measure the amplitude from the middle line to the crest ( never the tough ).

Question 9

What is a feature of vibrations in longitudinal waves?

Answer 9

• In Longitudinal waves the vibrations are along the same direction as the wave is travelling.

Question 10

What is a feature of the vibrations in transverse waves?

Answer 10

• In Transverse waves the vibrations are at 90 degrees to the direction of travel of the wave.

Question 11

How can ultrasound be produced?

Answer 11

• Electrical devices can be made which produce electrical oscillations of any frequency.
• These are converted into mechanical vibrations to produce longitudinal ( sound ) waves beyond the range of human hearing ( I.e. frequencies above 20,000 Hz ).
• This is called Ultrasound.

Question 12

What are some uses of Ultra sound?

Answer 12

• Body Scanning

- Breaking down accumulations in the body - Kidney stones.

Question 13

How does ultrasound remove kidney stones?

Answer 13

• The ultrasound concentrates high energy waves at the kidney stones and turns it into sand-like particles.
• These particles can then pass out of the body in urine.

Question 14

Why is it better to use ultrasound to remove kidney stones as opposed to other methods?

Answer 14

• It is non invasive, as the patient will not be carrying out surgery.
• It is relatively painless.

Question 15

How is ultrasound used for body scanning?

Answer 15

• Ultrasound waves can pass through the body, but whenever they reach a boundary between two different media ( like fluid in the womb and the skin of the fetus ) some of the wave is reflected back and detected returning back from different depths at different times.
• The exact timing an distribution of these echoes are processed by a computer to produce a video image of whatever is being scanning ( for example a foetus ).

Question 16

What are some advantages of using ultra-sound over x-rays?

Answer 16

1 : X-Rays pas easily though soft tissue such as muscles and skin, so you can only usually them to see hard things such as Bone, ultrasound is better for imaging soft tissue
2: Ultrasound doesn’t damage living cells, X-rays are ionising radiation. They can damage living cells and cause cancer if you are exposed to too high a dosage.