Because radioactive radiation can pass through materials, kill living cells and be detected even in tiny amounts, it has many useful applications. Each use is chosen to match the penetrating power and effect of a particular type of radiation.
Medicine
Gamma rays are used to sterilise medical equipment by killing bacteria. In radiotherapy, carefully controlled beams of gamma rays are aimed at tumours to destroy cancer cells. Small amounts of radioactive substances called tracers, such as iodine-131, are given to patients so that doctors can follow how an organ is working. Because the tracer gives out radiation, its path through the body can be followed with a detector outside the body, without the need for surgery.
Example
A smoke detector contains a weak alpha source. Smoke blocks the alpha particles, which changes the current and sets off the alarm. This tiny amount of radiation is safe for use in homes.
Industry, agriculture and dating
In industry, beta radiation is used to check the thickness of paper or metal foil, and gamma radiation helps find leaks in underground pipes. If the thickness is wrong, the reading changes and rollers can be adjusted automatically. In agriculture, radiation is used to kill pests and to study how plants take up fertiliser. Archaeologists use carbon-14 dating to estimate the age of very old objects such as bones and wood. As living things slowly lose carbon-14 after they die, the amount left behind acts like a natural clock.
Remember
- Gamma: sterilising, treating cancer.
- Beta: measuring thickness.
- Carbon-14: dating old materials.
- Always handle radioactive sources safely.