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Medical imaging

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Question 22

An ultrasound scan is a widely used non-invasive diagnostic technique in modern medicine.

a.

Explain what is meant by ultrasound.

[2]
b.

Describe how a piezoelectric transducer is utilized to both generate and detect ultrasound waves during a clinical scan, and explain why an acoustic coupling gel must be applied to the patient's skin before the probe is used.

[5]
c.

During a renal scan of a patient's abdomen:

Explain why virtually no ultrasound signal is reflected back to the transducer from within a large volume of uniform urine inside the bladder.

[2]
d.

During a renal scan of a patient's abdomen:

Explain why the boundary between soft kidney tissue and surrounding bone produces a much stronger reflection signal than the boundary between muscle and fat (two different types of soft tissue).

[3]
e.

A clinician uses a Doppler ultrasound probe to assess the speed of blood flow in a patient's carotid artery.

  • The speed of ultrasound in blood is taken as 1560 m s-1.
  • The transducer emits ultrasound waves at a frequency of 5.5000 MHz directed at an angle of 42∘ 42^\circ\,42∘ to the direction of the blood flow.
  • The frequency of the reflected ultrasound received back by the transducer is detected as 5.5018 MHz.

Calculate the speed v v\,v of the blood flow. Give your answer to 2 significant figures.

[4]
Markscheme

Medical imaging Questions

  1. A Level
  2. /Physics
  3. /Medical imaging

25 exam-style questions on OCR A A Level Physics Medical imaging, covering Using X-rays, Diagnostic methods in medicine, and Using ultrasound. Each one has a worked solution and a mark scheme showing where the marks go.

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