Radiation Safety @ CurtinRADIATION SAFETY INFORMATIONHere you can obtain information about the nature of radioactivity, sources of radioactivity and protection from radioactivity.
Radiation is the process of emitting energy in the form of waves and particles. Radiation occurs when the particles of an atom undergo a change in position, or energy. Matter that contains unstable atoms that frequently undergo such changes are said to be radioactive. The term radiation is more commonly used to describe these emissions. There are different types of radiation, each characterised by how energetic it is. Non-ionising radiation does not have enough energy to change things chemically, but ionising radiation can. Ionising radiation is the more energetic and is potentially the most harmful. There are three main types of ionising radiation:
Radiation and radioactive substances are natural and permanent features of the environment, and thus the risks associated with radiation exposure can only be restricted, not eliminated entirely. Additionally, the use of human made radiation is widespread. Sources of radiation are essential to modern health care: disposable medical supplies sterilized by intense radiation have been central to combating disease; radiology is a vital diagnostic tool; and radiotherapy is commonly part of the treatment of malignancies. The use of nuclear energy and applications of its by-products, i.e. radiation and radioactive substances, continue to increase around the world. Nuclear techniques are in growing use in industry, agriculture, medicine and many fields of research. Irradiation is used around the world to preserve foodstuffs as a sterilization technique. Industrial radiography is in routine use. There are three main concepts to remember in protecting yourself from radiation. They are:
This only describes the general concepts. There are radiation protection standards and guidelines you should be familiar with. These generally pertain to exposure and dosage. Exposure and Dosage; Quantities and Units Although most of the requirements of the Standards are qualitative, the Standards also establish quantitative limits, and guidance levels. For these purposes, the main physical quantities used in the Standards are the rate of nuclear transformation of radionuclides (the activity) and the energy absorbed by a unit mass of a substance from the radiation to which it is exposed (the absorbed dose). The unit of activity is the reciprocal second, representing the number of nuclear transformations (or disintegrations) per second, which is termed the becquerel (Bq). The unit of absorbed dose is the joule per kilogram, termed the gray (Gy). The absorbed dose is the basic physical dosimetric quantity of the Standards. However, it is not entirely satisfactory for radiation protection purposes because effectiveness in damaging human tissue differs for different types of ionizing radiation. Consequently, the absorbed dose averaged over a tissue or organ is multiplied by a radiation weighting factor to take account of the effectiveness of the given type of radiation in inducing health effects; the resulting quantity is termed the equivalent dose. The quantity equivalent dose is used when individual organs or tissues are irradiated, but the likelihood of injurious stochastic effects due to a given equivalent dose differs for different organs and tissues. Consequently, the equivalent dose to each organ and tissue is multiplied by a tissue weighting factor to take account of the organ's radiosensitivity. The sum total of such weighted equivalent doses for all exposed tissues in an individual is termed the effective dose. The unit of equivalent dose and of effective dose is the same as that of absorbed dose, namely joule per kilogram, but the name sievert (Sv) is used in order to avoid confusion with the unit of absorbed dose (Gy). When radionuclides are taken into the body, the resulting dose is received throughout the period of time during which they remain in the body. The committed dose is the total dose delivered during this period of time, and is calculated as a specified time integral of the rate of receipt of the dose. Any relevant dose restriction is applied to the committed dose from the intake. The total impact of the radiation exposure due to a given practice or source depends on the number of individuals exposed and on the doses they receive. The collective dose, defined as the summation of the products of the mean dose in the various groups of exposed people and the number of individuals in each group, may therefore be used to characterize the radiation impact of o practice or source. The unit of collective dose is the man--sievert (man.Sv). Dose exposure limits and maximum permissible exposure levels The following limits are given for the maximum permissible dose for occupational exposure.
Note that these are whole body exposures for those working in an area where radiation will be encountered. For those not working in these areas, there are different requirements:
This section lists useful resources for more detailed information on technical and health issues, regulations and standards.
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