Uses and hazards of radiation for OCR GCSE Physics
This page covers the following topics:
1. Radioactive contamination
3. Comparing radiation hazards
4. Uses of radiation
Contamination is when radioactive material is inserted into an object. Although contamination may be potentially hazardous, there are uses for contamination, such as medical contamination. Isotopes with a short half-life are used in contamination, so that the exposure of the object to radioactive material is contained. Further, the isotopes used must not be poisonous, so as not to cause any damage. A disadvantage of contamination is that the isotopes cannot be fully controlled and thus may not go where they were intended to go. Also, there may be some radioactive material leftover after contamination that may not be possible to fully remove. Finally, radioactive materials may damage or potentially mutate human cells.
Irradiation is the process of exposing objects to radiation without making them radioactive. Irradiation can be stopped by suitable shielding of the object and by moving it away, and the process will stop as soon as the source of the radioactive beams is removed. Irradiation can be hazardous, as exposing people's cells to radiation beams may cause their damage and mutation. However, although it may not kill all bacteria, irradiation is useful for sterilisation. It eliminates the need of high temperatures, thus allowing objects that would otherwise melt to be sterilised.
Both irradiation and contamination may cause damage or even mutation to people's cells, as they are being exposed to radioactive material. However, there are some differences in the hazards associated with the two processes. While irradiation doesn't make the object radioactive, contamination will for the time in which the radioactive material is in the object. Irradiation is performed through an external source of radioactive material, whereas contamination required for it to be in or on the object. Contamination can be seen as more hazardous than irradiation, since irradiation can be blocked using shielding, whereas contamination can't. Further, irradiation stops when the radioactive source is removed, whereas the radioactive material used in contamination may be difficult to be fully removed.
Different types of radiation have different uses. Alpha radiation is used in smoke detectors by ionising the air inside it. In the case of a fire, the smoke will disrupt the ionisation and turn the alarm on. Beta radiation is used in medical imaging. Radiation will gather around damaged organs and detectors will be able to detect the radiation being emitted, and thus an internal image is constructed. This is also achieved through the use of gamma radiation. The isotope injected into the body will emit gamma rays outside it and a detector will be able to follow its path to be able to identify any soft tissue or blockages inside the body. Such radioactive sources used in medical imaging are called tracers. Gamma radiation is also used for cancer treatment by killing cancer cells, and the sterilisation of medical equipment by killing bacteria.
How can beta radiation be used in medical imaging?
A radioactive source will be injected into the body. Radiation will gather around damaged organs and detectors will be able to detect the beta radiation being emitted out of the body, and thus an internal image is constructed.
Explain how irradiation may be used in supermarkets to help preserve fruit.
Exposing fruit to radiation beams through irradiation will sterilise the fruit, and thus will remove bacteria from me. This will help preserve the fruit without making the fruit itself radioactive.
Contamination is when radioactive material is inserted into an object.
What is the difference between the ways in which irradiation and contamination are performed?
For irradiation to occur, the object has to be exposed to a source of radioactive material, whereas for contamination, the radioactive material must be inserted into or onto the object.
State a disadvantage of sterilisation through irradiation.
Sterilisation through irradiation may not kill all bacteria on the object.
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