# Radioactive materials can be used as tracers in medicine. A doctor injects a patient with a radioactive tracer that emits gamma radiation. Explain why gamma-emitting isotopes are chosen for use inside the body as medical tracers, rather than isotopes that emit alpha or beta radiation.

> Eduqas A-Level Physics — 3.5 Nuclear decay · Explain · 5 marks

## Mark scheme (5 marks)

1. Gamma radiation can penetrate through body tissue / organs to be detected outside the body
2. Alpha radiation has very short range / is stopped by a few centimetres of air or skin and would not be detected outside the body
3. Alpha radiation causes the most ionisation (inside the body) / would cause the most damage to body cells / tissues
4. Beta radiation has greater penetration than alpha but is still largely absorbed by body tissue / does not penetrate as well as gamma
5. Gamma radiation has the lowest ionising power / causes the least ionisation damage to body cells, making it the safest option inside the body

## Key terms

- [gamma radiation](https://www.gradenine.co.uk/glossary/gamma-radiation)
- [beta radiation](https://www.gradenine.co.uk/glossary/beta-radiation)
- [tracer](https://www.gradenine.co.uk/glossary/tracer)

## Related

- [Revision notes for Eduqas A-Level Physics](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/radioactive-materials-can-be-used-as-0166210c) · Published by Druglandscape Ltd.