# A hospital uses radioactive tracers to image internal organs. Technetium is commonly used as a medical tracer. Explain why technetium is a suitable radioactive isotope for use as a medical tracer inside the human body.

> OCR A-Level Physics A (H556) — 6.2 Electric and magnetic fields · Explain · 5 marks

> Technetium is a gamma emitter with a half-life of 6 hours. It decays into a stable isotope that can be excreted by the body. It is either injected or swallowed by the patient so that it travels through the body and can be detected externally.

## Mark scheme (5 marks)

1. Technetium is a gamma emitter, so gamma radiation can pass through body tissue to be detected outside the body
2. Gamma radiation has the least ionising power, so it causes minimal damage to body tissue / cells
3. The half-life of 6 hours is short enough that the technetium decays away quickly, reducing the long-term radiation risk to the patient
4. The half-life of 6 hours is long enough for the technetium to travel through the body and be detected before it decays away
5. Technetium decays into a stable / safe isotope that can be excreted by the body, so no long-term radioactive material remains inside the patient

## Key terms

- [isotope](https://www.gradenine.co.uk/glossary/isotope)
- [tracer](https://www.gradenine.co.uk/glossary/tracer)

## Related

- [Revision notes for OCR A-Level Physics A (H556)](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-radioactive-tracers-to-2e94e4d7) · Published by Druglandscape Ltd.