Uses of radioactivity

What nuclear emissions are used for medical purposes?

• Gamma rays

• Beta particles

What are the implications of the short half life of certain emissions?

• Do not stay in the body for too long

What are the implications of the long half life of certain emissions?

• Stay in the body for a long time

• Only a small quantity is needed over a long time

How are gamma rays used for medical purposes?

Detection of tumors

• Technetium-99 (short 6h half life) is taken into the body

• Emits gamma rays that allow images of internal organs to be taken with the help of a gamma camera, helping in diagnosis

Gamma knife radiosurgery

• Gamma rays from cobalt-60 (long 5.3y half life) are directed at the brain to destroy brain tumors

How are beta particles used for medical purposes?

Treatment of thyroid disorder

• A small amount of iodine-131 (short 8d half-life) is taken into the body

• Beta particles emitted can destroy thyroid cells including cancer cells

What nuclear emissions are used for safety purposes? 

Gamma rays

How are gamma rays used for safety purposes?

Killing microbes in food

• Gamma rays kill microbes whose action causes the decay of food, making food no longer safe for consumption

Sterilising medical equipment

• Medical equipment like syringes and scalpels are kept in sealed packages  and exposed to gamma rays that kill microbes

*Isotopes have long half lives of a few years

What nuclear emissions are used for geological purposes?

Alpha particles

How are alpha particles used for geological purposes?

Estimating the age of rocks

• Uranium-238 (long half life of 4.5b years) is found in most rocks and it decays to a stable isotope lead-206

• Relative amount of each isotope in a sample can be determined

• More lead-206 → older rock

What nuclear emissions are used for penetration abilities and ionizing effects?

• Alpha particles

• Beta particles

• Gamma rays

How are nuclear emissions used in smoke detectors?

• Alpha particles are emitted by americium-241 (long half-life of 432 years)

• Particles fall on smoke detector and current flows into the detector due to particles’ high ionizing ability

• Smoke easily absorbs the radiation, disrupting the flow of current and trigger the detector’s alarm

How are nuclear emissions used in measuring the thickness of materials?

• Beta particles or gamma rays from a radioactive source are directed at a material, depending on the type of material

• Manufacturers need their materials to be of uniform thickness

• Thick material → low amount of radiation

Beta → Thin materials (gamma will always penetrate)

Gamma → Thick materials

Alpha is unsuitable as they will be absorbed by most materials easily

How can we limit contamination with radioactivity?

1. Leave the area quickly

2. Remove the outer layer of clothing

3. Wash all exposed parts of the body with soap and lukewarm water to remove radioactive materials from the body

How do we reduce exposure time with radioactivity?

• Only carry out experiments involving radioactive materials in designated locations

• The locations are only meant for work that requires the use of ionizing radiation

How do we increase the distance between the radioactive materials and living tissue?

• The intensity of ionizing radiation decreases with distance

• Use long tongs or remote-controlled devices

How do we use shielding to protect ourselves from radiation?

• Use materials that absorb ionizing radiation while performing experiments involving ionizing radiation

• E.g. lead-lined gloves and suits, thick concrete walls and doors

How do we use storage to protect ourselves from radiation?

• Store radioactive materials in a sealed container that will absorb the radiation

• Prevents nuclear radiation from penetrating the container and escaped into air

• Boxes should be clearly labelled and not kept in an easily accessible place