Uses and risks of radiation

​​In a nutshell

Although there are risks associated with it, radiation has uses in everyday life. Alpha sources are used in smoke detectors. Beta sources are used to detect how thick a piece of material is. Gamma sources can be used as medical tracers, in radiotherapy and to sterilise food and equipment.

Alpha radiation

Smoke detectors

Alpha radiation ionises the air it passes through. This ionisation can cause a current to flow between two electrodes. 

1. Alpha source 2. Electrodes 3. Air gap 4. Current 5. Alpha particles ionizing air 6. Alarm

When there is a fire, smoke in the air blocks the alpha particles from travelling through the air. This prevents a current from being generated which results in the alarm sounding.

The alpha sources used in smoke detectors have long half-lives. This is so they don't need replacing very often.

Beta radiation

Thickness of sheets

Beta sources can be used to test the thickness of materials. This is because they are able to travel a certain distance without being absorbed, unlike alpha particles which would all be absorbed or gamma which would all get through. The beta particles that can pass through a material can be detected using a radiation detector. 

The thicker the material, the more beta particles the material will absorb. The thinner the material, the less beta particles the material will absorb.

Example

This method is often used to keep the thickness of a material constant. Machines that make aluminium foil use the detections to make adjustments to keep the thickness of the foil constant.

1. Aluminium foil 2. Radiation detector 3. Beta emitter

Gamma radiation

Medical tracers

Gamma sources can be used as medical tracers. Patients are injected with or swallow gamma sources and their position through the body can be tracked using a detector.

Gamma radiation is used as it passes out of the body without causing much ionisation. The sources also have a short half-life which means the radioactivity disappears quickly.

Example

Iodine-$$123$$​ is used to determine whether the thyroid gland is behaving correctly. The source injected into the body is absorbed by the thyroid gland and can be measured.

Radiotherapy

Gamma rays are a type of ionising radiation. Large amounts of ionising radiation kills living cells, which is useful in radiotherapy.

The rays are directed at tumours (cancer cells) to kill them. This has to be done carefully as the surrounding normal cells can also be damaged. The damage caused may result in the patient feeling ill.

Sterilisation

Gamma radiation is also used in the sterilisation of food and medical equipment. This is because it is highly penetrating so it can sterilise objects without having to remove their packaging. It can also irradiate (expose to radiation) all sides of the medical instruments. 

Risks of radiation

As well as having many uses, there are dangers to using radiation. 

When radiation enters living cells, it can ionise the molecules within them. Lower doses of radiation can cause minor damage which may lead to mutant cells. These cells divide uncontrollably which is labelled as cancer. Higher doses can kill cells which leads to radiation sickness.