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

> OCR A-Level Physics B: Advancing Physics (H557) — 6.2 Electric and magnetic fields · Explain · 5 marks

> Technetium is injected into a patient and its radiation is detected outside the body to build up an image of an internal organ. Technetium has a half-life of 6 hours and is a gamma emitter.

## Mark scheme (5 marks)

1. Technetium is a gamma emitter, so the radiation can pass through body tissue without being absorbed / is highly penetrating
2. The gamma radiation can be detected outside the body / by a detector placed outside the patient
3. The half-life of 6 hours is short enough that the technetium decays / activity dies down relatively quickly, reducing long-term radiation risk to the patient
4. The half-life of 6 hours is long enough for the technetium to flow through the body and be detected before it decays away
5. Technetium decays into a safe / stable isotope that can be excreted / removed from the body

## Key terms

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

## Related

- [Revision notes for OCR A-Level Physics B: Advancing Physics (H557)](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/a-hospital-uses-technetium-as-a-2cf7a026) · Published by Druglandscape Ltd.