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GCSE Questions: Medical Physics

- scanning and therapy

 

Q13. These photos show one medical use of ultrasound and one medical use of X-rays.

(a) Ultrasound and X-rays are commonly used in hospitals.

(i) What is the minimum frequency of ultrasound waves? 20,000 Hz

(ii) The wavelength of an X-ray is about the same as the diameter of something. What is that 'something'? An atom

[3 marks]

(b) Compare the medical uses of ultrasound and X-rays. Your answer should include the risks, if any, and precautions, if any, associated with the use of ultrasound and X-rays.

This type of question is marked in two ways:

- the examiner looks for relevant points

- but also for a logical sequence...

It is not just a 'tick fest' - but a marker does look to see how many relevant points you have made, then considers how you have strung them together to put your answer into a 'level'

Level 3:

At least one medical use is given for both types of wave linked to the risks and any precautions necessary
5 - 6 marks
Level 2:

Either

A use, risk and precaution is given for one type of wave

Or

A medical use is given for both types of wave plus a risk or precaution for one type of wave

3 - 4 marks
Level 1:

At least one relevant statement is given for either type of wave
1 - 2 marks
Level 0:

No relevant information
0 marks

 

Examples of physics points that should be made in the response:

Medical use of X-rays

Any one from:

Detecting bone fractures

Detecting dental problems

Killing cancer cells

CT scanning

Risks with X-rays

X-rays pose a risk / danger / hazard because

X-rays cause ionisation / damage to cells or mutate cells / cause mutations / increase chances of mutations

or

turn cells cancerous / produce abnormal growths / produce rapidly growing cells or kill cells

Operator precautions with X-rays

The X-ray operator should go behind a (metal / glass) screen / leave the room when making an X-ray / wear a lead lined apron

Medical use of ultrasound

Any one from:

Pre-natal scanning

Imaging (a named body part).

removal / destruction of kidney / gall stones

removing plaque from teeth

repair of damaged tissue / muscle

Risks with ultrasound Ultrasound

poses no risk / danger / hazard (to the user / patient).

Ultrasound is not ionising

or

Ultrasound does not damage (human) cells

Precautions with ultrasound

The operator needs to take no precautions when making an ultrasound scan.

[6 marks]

(Total 9 marks)