Radiation Protection Today - Winter 2022 Issue 4 | Page 36


Do you know anyone who ' d like to learn a bit more about radiation ? This pull-out sheet will help .
What is the difference between Radiation , Radioactivity and Contamination ?
Very often radiation is confused with radioactivity and radioactive contamination , so to understand the difference we need to appreciate what we mean by these terms .
Radiation is a source of energy that is emitted , either in the form of particles or packets of energy . It may be created by a material which is radioactive or generated artificially by machine , such as X-rays .
External Radiation The body can be exposed to radiation and contamination in several ways . It can be by direct exposure to radiation , where the radiation is of sufficient energy to transmit through the body , such as X-rays and gamma rays . This is called ' external ' radiation ( the source of the radiation is outside the body ).
Gamma or X-ray radiation is more penetrating and requires very dense material to shield it . The ‘ half value layer ’ is the thickness of material required to reduce the intensity of incident radiation by half .
Radioactivity is the process by which an unstable atom undergoes a transition in an attempt to become stable . This process is known as radioactive decay and results in the emission of radiation in the form of particles ( alphas , betas , neutrons and protons ), gamma rays or X-rays .
Contamination is the presence of another substance on a place or item where it is not expected to be . Radioactive contamination of surfaces may be in the form of a liquid or solid .
Internal Radiation The body can be exposed to radioactive contamination via inhalation , ingestion or injection ( such as through a wound ), or it may be absorbed through the skin . This is called ' internal radiation ' ( the source of radiation is inside the body ).
Once inside the body , radioactive material will undergo decay , causing cells to be irradiated . Depending on the type of radioactive material , processes in the body may cause it to become concentrated in different organs , or it may pass through the body and be excreted .
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