Physics - Putting Radiation To Use

Smoke detectors use alpha particles

1) A weak source of alpha particles is put into the detector

2) The source causes ionisation and a current will flow

3) If there is a fire, the radiation will absorb the smoke and the alarm will go off.

Tracers in medicine - gamma and beta particles

1) Certain radioactive isotopes can be injected (or swallowed) into the body and their progress can be monitored using an external detector

2) All isotopes injected into the body MUST be gamma or beta particles so that they can pass out of the body. They should only last a few hours so that the radioactivity inside the patient goes quickly. (must have a short half life.) 

Radiotherapy - Gamma Rays

• As gamma can kill all living cells, they can be used to treat cancer by killing the cancerous cells.
• It is important that the right direction and dosage is used to ensure as little as possible of the healthy cells are damaged
• It is expected that a fair amount of the healthy cells will be damaged, leaving the patient feeling quite ill. However, if it gets rid of the cancer, it is worth it in the end.

Sterilisation of food and surgical instruments - Gamma

• Gamma rays can be used to sterilise food. It can kill the microbes in food, keeping the food fresher for longer.
• They can also be used to sterilise surgical equipment instead of boiling it.
• The advantage of irradiation over boiling is that you do not need high temperatures.
• It does not leave the food radioactive.

Alpha, beta and gamma can all enter living body cells and collide with molecules.

This can lead to the production of mutant cells which divide rapidly. 

These are cancerous cells.

Outside the body, gamma and beta are most dangerous - This is because they can get inside and cause damage to vital organs. However, alpha cannot as it cannot penetrate the skin

Inside the body, alpha is the most dangerous because it works in localised areas. Beta and gamma, however, mostly pass through the body.