Gamma radiation is used in the treatment of cancer tumours. Explain why gamma radiation is used for this purpose and describe the precautions that must be taken to protect healthy tissue during treatment.

Eduqas GCSE Physics — 9.3 Hazards and uses of radioactive emissions · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

Gamma radiation is highly penetrating, so it can pass through the body and reach the tumour.
It kills cancer cells by damaging their DNA, thereby destroying the tumour.
During treatment the gamma beam is aimed at the tumour from many angles, rotating around the patient.
This technique concentrates the highest dose on the tumour while the surrounding healthy tissue receives a lower dose, protecting it.

Examiner tips

  • Use the term "highly penetrating" and link to tumour reach. Mention DNA damage to justify cell death. Explain multi‑angle beam and rotation. Show how dose distribution protects healthy tissue.

Common mistakes

  • Confusing gamma with X‑ray or beta radiation. Failing to mention the multi‑angle beam. Not explaining why healthy tissue is spared.

Mark scheme (4 marks)

  1. Gamma radiation is highly penetrating / can penetrate the body to reach the tumour
  2. Gamma radiation kills (cancer) cells / destroys the tumour
  3. The beam of gamma radiation is directed at the tumour from multiple angles / rotated around the patient
  4. This means healthy tissue receives a lower dose (than the tumour) / the tumour receives the highest dose while surrounding tissue is protected

Key terms in this question

gamma radiation · tumour · healthy tissue

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