7.13 describe the uses of radioactivity in medical and non-medical tracers, in radiotherapy, and in the radioactive dating of archaeological specimens and rocks

Medical tracers
This method is used for doctors to find out whether a persons organs are working as they should be. Alpha can not be used as it does not penetrate human skin and is strongly ionising, but beta and gamma can be used at it will penetrate human skin and body tissue.

The process...
- A source which  emits beta or gamma radiation is injected or swallowed.
- The source moves around the body and the radiation will penetrate the body tissues and can be detected externally by a radiographer with a detector
- A computer converts the reading to a screen display which shows where the radiation is coming from

NOTE: The radioactive source they use would have to have a short half-life so it does not damage the person.

Non-medical tracers
Industrial tracers can be used for looking for things like leaks in underground pipes (using a tracer you would not need to dig out the pipe to find the leak, it's just a little bit less hassle).

The process...

- Put a gamma source into the pipe and let it flow through the pipe. Detect where the radiation goes with a detector above ground (follow it)
- When you reach the point where there is a hole in the pipe, there will b a much larger reading of radiation on the detector as lots of radiation will have escaped.

NOTE: A gamma source must be used, as beta or alpha would be stopped by the earths rocks and there would be a very little (if any) reading. It should also have a short half-life as it could cause damage if it stays/collects somewhere (think Chernobyl and Fukushima, but on a smaller scale)

Radioactive dating
Radioactive dating enables archaeologists to accurately work out the age of rocks, fossils and archaeological specimens (for example, Egyptian mummys)

If you know the half-life and amount of radioactive isotope in a sample, you can work out how long it has been around.

By comparing the activity level of an archaeological sample to a sample of living tissue, you can work out the amount of Carbon-14 half-lives that have passed (for example). This can give you an idea of how long ago the sample was living/died.

NOTE: an alternative is to look at the  ratio of Carbon-14 to Carbon-12 as this is fixed in living materials, so by comparing the ratio in a living and non living sample you can estimate the age of the sample.