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Non-ionising imaging (A-level only)

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Question 1

An ultrasound scan of frequency 3.8 MHz3.8\text{ MHz}3.8 MHz is used to image a boundary between kidney tissue and a kidney stone (calcium deposit) during a diagnostic procedure.

a.

Estimate the resolution of the scan in kidney tissue, assuming the resolution is approximately equal to the wavelength of the ultrasound in the tissue.

[2]
b.

Calculate the acoustic impedances of the kidney tissue and the kidney stone.

[2]
c.

Calculate the percentage of the incident ultrasound intensity that is transmitted across the kidney-stone boundary.

Data:

  • Speed of sound in kidney tissue = 1560 m s−11560\text{ m s}^{-1}1560 m s−1
  • Density of kidney tissue = 1050 kg m−31050\text{ kg m}^{-3}1050 kg m−3
  • Speed of sound in kidney stone = 2510 m s−12510\text{ m s}^{-1}2510 m s−1
  • Density of kidney stone = 2160 kg m−32160\text{ kg m}^{-3}2160 kg m−3
[3]

Non-ionising imaging (A-level only) Questions

  1. A Level
  2. /Physics
  3. /Non-ionising imaging (A-level only)