The uses of Radioisotopes in various fields

Isotopes are different forms of an atom of the same chemical element. They have identical chemical properties but a different relative atomic mass. While the number of protons is the same, the number of neutrons in the nucleus differs. Some isotopes are referred to as 'stable' and others as 'unstable' or 'radioactive'. It is the radioactive nature of these unstable isotopes, usually

referred to as 'radioisotopes', which gives them so many applications in modern science and technology.

Medicines

Radiotherapy (Cobalt-60 )

- Destroy cancer cells in patients

Tracer to Detect Blood Clots or Tumour (Sodium-24)

- A small amount of sodium-24 is injected into the patient's body.

- Radioactive imaging is then used to detect accumulation of sodium-24 and therefore detect tumours and blood clots before they become dangerous.

Sterilising Medical Instrument (Cobalt-60)

- Gamma ray emitted from radioactive cobalt-60 can kill germs such as bacteria and fungus.

- Medical instruments such as surgical equipment, syringes and bandages can be sterilised by using gamma rays.

Heart Pacemaker (Plutonium-238)

- A heart pacemaker is a medical device which uses electrical pulses to contract the heart muscles, and hence

to regulate the beating of the heart.- Plutonium-238 in a nuclear battery is used to produce

small electric shocks in the heart pacemaker.- People with irregular heartbeats need to have a heart

pacemaker implanted inside their chest.-

Tracer to Investigate Activities of Thyroid Glands (iodine-123 or iodine-125)-A radioactive tracer is a substance containing a radioisotope that is used for tracking purposes.-In medicine, radioactive substances are introduced into the body of patients and the radiation --emitted is detected by using a gamma camera. This diagnostic process is known as radioactive imaging.-In medicine, radioactive iodine-123 or iodine-125 is introduced into patient's body.-The rate of accumulation of radioactive iodine in thyroid glands is measured through radioactive imaging. This is used to evaluate the function of the thyroid gland.

Industries

Monitoring Content of Food

Monitoring Thickness of Steel/paper Sheet

Detecting Underground Leakage

Measuring the Wearing Rate of

Engine

Agriculture

Pest Control

- Male insect is sterilised by exposing to

radioactive radiation and then released back to the ecosystem.

- This can ensure that their reproducing effort do not generate new generation and hence

reduces the population of the insect.

Tracer- The metabolism of phosphorus by plants

can be studied using phosphate fertilisers that contain phosphorus-32.

- A small amount of phosphorus-32 is used in fertilisers.

- The radiation produced by phosphorus-32decay is detected by a Geiger-Muller counter.

- This method can trace the passage of phosphate ions in plants.

- Carbon-14 is used to study the passage of carbon during photosynthesis in plants.

Develop New Species of Plant

- Radioactive radiation is targeted to the seeds of plants and hence causes mutation to the genes.

- By chance, this may develop some superior agricultural products.

Preserve Food

- The gamma rays from cobalt-60 are used to kill bacteria in food to make fresh vegetables and fruits last longer without any change in quality, flavour and

texture of food.

- Gamma rays are used to inhibit budding in potatoes.

Archeology

- In archaeology radioisotope carbon-14 is used to study and estimate the age of

ancient artifacts. This method is named as the radiocarbon dating.

- Radiocarbon dating can be used to estimate the age of organic materials, such as wood and leather, up to about

58,000 to 62,000 years.

Example:

A piece of wood found in a cave of an archaeology site has a carbon-14 activity 25% of the activity from a live plant. Estimate the age of the wood. [Half-life of carbon-14 = 5730 years]

Answer:

100% → 50% → 25%

Carbon-14 take 2 half-life to decay from 100% to 25%, hence the age of the wood

Shorter notes

Medicine Technetium-99m: injected in blood stream to detect brain cancer, internal hemorrhage, and blood clotsSodium-24: to detect blood clotCobalt-60: kill cancer cells in radiotherapy, sterilization of hospital equipmentPhosporus-32: to detect brain tumourIodine-131: to determine thyroid glandsIron-59: to trace iron distribution in blood

Agricultur e

The rate and quantity of fertilizer absorption by plants can be determined by mixing radioactive phosphate into the fertilizer.

Radioactive radiation from radioisotopes are used to kill pests.

Pests can also be multiplied in the lab and exposed to gamma rays, where they will mutate to infertility.

Control ripening of fruits.

A piece of wood found in a cave of an archaeology site has a carbon-14 activity 25% of the activity from a live plant. Estimate the age of the wood. [Half-life of carbon-14 = 5730 years]

Answer:

100% → 50% → 25%

Carbon-14 take 2 half-life to decay from 100% to 25%, hence the age of the wood

Archeology Carbon dating with carbon-14

Industry Gamma rays are used to penetrate deep into weldings to detect faults. Water leaks are determined by dissolving sodium-24 salt into the water and the pipes are checked with a GM tube. Polonium-210 is used to neutralize static charge in photographic plates. Americium-241 is used in smoke detectors. Automatic thickness control of paper, plastic and metal sheets. Automatic check of level of fullness within tins and packages.