Explain why patients and radiographers are at risk of harm from X-rays, and describe two precautions taken to reduce the risk to each group.

AQA A-Level Physics (7408) — 3.10.5 X-ray Imaging · Explain · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (5 marks)

X‑rays are ionising radiation, so they can damage or mutate cells and DNA, which increases the risk of cancer.

Patients:
1. A lead shield or lead apron is placed over the body parts that are not being imaged to absorb the X‑rays.
2. The exposure time is kept as short as possible and the minimum dose is used, limiting the number of X‑rays taken.

Radiographers:
1. They stand behind a lead screen during the exposure.
2. They leave the room during the exposure to increase the distance from the source.

Examiner tips

  • Use the exact terms ‘ionising radiation’, ‘lead shield/apron’, ‘minimum dose’ and ‘lead screen’ to match the mark scheme.
  • Show the two precautions for each group separately to earn the full 5 marks.

Common mistakes

  • Confusing X‑rays with non‑ionising radiation, or omitting the lead shield as a patient precaution.
  • Failing to mention the radiographer’s distance from the source or the use of a lead screen.

Mark scheme (5 marks)

  1. X-rays are ionising radiation
  2. Ionising radiation can damage or mutate cells / DNA, increasing cancer risk
  3. Patient precaution: lead shield / lead apron placed over parts of the body not being imaged to absorb X-rays
  4. Patient precaution: keep exposure time as short as possible / use the minimum dose needed / limit the number of X-rays taken
  5. Radiographer precaution: stands behind a lead screen / leaves the room during the exposure to increase distance from the source

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