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GCSE Questions: Medical Physics

- scanning and therapy

Q5.CT scans are used by doctors to create three-dimensional images of a patient's body.

(a)

(i) Explain why CT scans can increase the risk of cancer to the patient.

CT scans use ionisating radiation (X-rays) and these can cause mutations in the cells/dna of the patient when they ionise atoms/molecules within the body.

References to mutations/damage to cells were insufficient on their own - you needed to say how they occurred.

[2 marks]

(ii) Although CT scans increase the risk of cancer they are still carried out. Suggest why.

Because the (potential) benefits of a diagnosis outweigh the risks.

[1 mark]

(b) A child has a CT scan. Her mother stays in the room with her during the scan. Suggest one precaution that the mother should take during the scan.

Wear a lead vest or stand behind a safety screen

[1 mark]

(c) Ultrasound can also be used to create three-dimensional images of a patient. State one advantage of using CT scans rather than ultrasound scans.

CT scans give a higher quality (or resolution) image (or clearer image) than ultrasound.

OR 'They can differentiate more clearly between different types of tissue'

'Are more accurate or precise' was not worthy of a mark.

[1 mark]

[Total: 5 marks]