Irradiation
A torch beam lights up a person's hand because the hand is exposed to light, which is visible Energy travelling as waves in the form of changing electrical and magnetic fields.. Exposing objects to beams of Energy carried by particles from a radioactive substance, or spreading out from a source. is called Process of exposing an object to a source of radiation. Eg fruit exposed to gamma rays in order to destroy bacteria is said to have been irradiated.. This term applies to all types of radiation, including radiation from the Nuclei is the plural of nucleus. The nucleus is the central part of an atom. It contains protons and neutrons, and has most of the mass of the atom. of The smallest part of an element that can exist..
Irradiation from The process in which unstable atomic nuclei break apart or change, releasing radiation as they do so. can damage living cells. However, it can be put to good use as well as being a hazard.
Irradiation for sterilisation
Irradiation can be used to preserve fruit sold in supermarkets. The fruit is exposed to a When unstable atoms give off particles that can be harmful to humans. source, typically cobalt-60. The The shortest wavelength and highest energy part of the EM spectrum. Produced by radioactive materials. emitted by the cobalt-60 nuclei destroy bacteria on the fruit without changing the fruit in any significant way. The process does not cause the irradiated object itself to become radioactive.
Medical irradiation
Doctors use radioactive sources for The process of ensuring that a sample contains no living things. of surgical instruments. They may also use beams of gamma rays to kill cancerous tumour cells deep inside the body. The beams are aimed at the tumour from many different directions. This:
- maximises the dose on the tumour cells, but
- minimises the dose on the surrounding soft tissue cells
This technique can damage healthy tissue, so careful calculations are done to find the best dose. This is enough to kill tumour cells but not so high that healthy tissue is damaged.
Efforts are made to ensure that irradiation does not cause any long-term effects. This is done by considering:
- the nature of the radioactive decay (A type of ionising radiation consisting of 2 protons and 2 neutrons., A type of ionising radiation consisting of a single electron. or A type of ionising radiation that is also part of the EM spectrum. It has no mass.)
- the Poison level. of the radiation
Advantages and disadvantages of irradiation
Advantages
- sterilisation can be done without high temperatures
- it can be used to kill bacteria on things that would be damaged by heating
Disadvantages
- it may not kill all bacteria on an object
- a person standing in the environment where objects are being treated by irradiation could suffer cell damage and cell A random and spontaneous change in the structure of a gene, chromosome or number of chromosomes.