Applications of radio-isotopes
The radio-isotopes have wide applications in medicine, agriculture, industry and research. A radio-isotope is added to a particular system and the course of the isotope is studied to understand the system.
(i) Medical applications
In medical field, radio-isotopes are used both in diagnosis and therapy. Radio cobalt (Co60) emitting γ−rays is used in the treatment of cancer. Gamma rays destroy cancer cells to a greater extent.
Radio-sodium (Na24) is used to detect the presence of blocks in blood vessels, to check the effective functioning of heart in pumping blood and maintaining circulation. Radio-iodine (I131) is used in the detection of the nature of thyroid gland and also for treatment. Radio-iodine is also used to locate brain tumours.
Radio-iron (Fe59) is used to diagnose anaemia. An anaemic patient retains iron in the blood longer than normal patient.
Radio-phosphorous (P32) is used in the treatment of skin diseases.
In agriculture, radio-isotopes help to increase the crop yields. Radio-phosphorous (P32) incorporated with phosphate fertilizer is added to the soil. The plant and soil are tested from time to time. Phosphorous is taken by the plant for its growth and radio-phosphorous is found to increase the yield.
Sprouting and spoilage of onions, potatoes, grams etc. are prevented by exposure to a very small amount of radiation. Certain perishable cereals remain fresh beyond their normal life span when exposed to radiation.
In Industry, the lubricating oil containing radio-isotopes is used to study the wear and tear of the machinery.
(iv) Molecular biology
In molecular biology radio-isotopes are used in sterilising pharmaceutical and surgical instruments.
(v) Radio-carbon dating
In the upper atmosphere, C14 is continually formed from N14 due to the bombardment by neutrons produced from cosmic rays.
7N14 + 0n1 -- -- > 6C14* + 1H1.
The C14 is radioactive with half life of 5570 years.
The production and the decay of C14 are in equilibrium in atmosphere. The ratio of C14 and C12 atoms in atmosphere is 1 : 106. Hence, carbon dioxide present in the atmosphere contains a small portion of C14.
Living things take C14 from food and air. However with death, the intake of C14 stops, and the C14 that is already present begins to decay. Hence the amount of C14 in the sample will enable the calculation of time of death i.e, the age of the specimen could be estimated. This is called radio-carbon dating. This method is employed in the dating of wooden implements, leather clothes, charcoal used in oil paintings, mummies and so on.