# A hospital uses a radioactive tracer to investigate a patient's internal organs. The tracer is a gamma emitter with a half-life of six hours. Explain why a gamma emitter with this half-life is suitable for use as a medical tracer inside the body.

> Edexcel GCSE Physics (1PH0) — 6.1 Radioactivity · Explain · 4 marks

> Radioactive tracers are used in hospitals to help doctors diagnose conditions. The tracer is introduced into the patient's body and an external detector monitors where it collects.

## Mark scheme (4 marks)

1. Gamma radiation is highly penetrating, so it can pass out of the body to be detected externally.
2. Gamma radiation is only weakly ionising, so it causes minimal damage to the patient's body tissues / cells.
3. A half-life of six hours is long enough for the tracer to be administered and for the imaging to be completed.
4. A half-life of six hours means the activity decreases quickly after the procedure, reducing the patient's long-term exposure to radiation / the tracer does not remain radioactive in the body for a long time.

## Key terms

- [half-life](https://www.gradenine.co.uk/glossary/half-life)

## Related

- [Revision notes for Edexcel GCSE Physics (1PH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-hospital-uses-a-radioactive-tracer-85f3a928) · Published by Druglandscape Ltd.