Physics · OCR H556 · Topic 6.5

Medical imaging

Using X-rays, diagnostic methods in medicine, using ultrasound.

  • 3 sub-topics
  • Taught in Year 13
  • 38 practice questions
  • 3 animated lessons
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What the specification says

Every sub-topic OCR can examine in this topic, with its reference number from the official specification. The Y12 and Y13 tags show when each sub-topic is usually taught.

  1. 6.5.1Using X-raysY13
  2. 6.5.2Diagnostic methods in medicineY13
  3. 6.5.3Using ultrasoundY13

Try 2 questions

Easy and medium questions from this topic, each with a worked solutions and the mark for every step. All 38 questions in this topic, free, no account needed.

Medical physics

Not needed for Year 12Easy

Image detection and enhancement · Year 13 · 3 marks

X-ray images can be recorded on photographic film or with flat-panel detectors.
  1. (a)
    Explain how an intensifying screen reduces the dose to the patient.
    (2)
  2. (b)
    Give one advantage of a flat-panel detector.
    (1)
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Part (a)2 marks

  1. A fluorescent screen emits many visible photons for each X-ray photon,
  2. so the film needs a shorter exposure.

Part (b)1 mark

  1. Images are digital and immediate, and can be enhanced and stored.

Total3

  • M
  • A
  • B
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Medical physics

Not needed for Year 12Medium

Absorption of X-rays · Year 13 · 4 marks

An X-ray beam of intensity 100 W m⁻² passes through 0.5 cm of tissue with linear attenuation coefficient 0.5 cm⁻¹.
  1. (a)
    Calculate the transmitted intensity.
    (2)
  2. (b)
    Calculate the half-value thickness.
    (1)
  3. (c)
    Explain why barium meal contrast media are used for the gut.
    (1)

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Part (a)2 marks

  1. I=I0e−μxI = I_0\mathrm{e}^{-\mu x}
  2. I=77.9 W m−2I = 77.9\ \mathrm{W\,m^{-2}}

Part (b)1 mark

  1. x1/2=1.39 cmx_{1/2} = 1.39\ \mathrm{cm}

Part (c)1 mark

  1. Barium has a high attenuation coefficient, so the gut shows up clearly against soft tissue.

Total4

  • M
  • A
  • B
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