| Extremely short wavelength and intensely high-energy electromagnetic radiation. Gamma rays originate from an atom's nucleus and normally accompany alpha and beta particles as part of the emissions of the radioactive decay of an atom and always accompany nuclear fission. Because gamma rays are energy and not matter, they are very penetrating and can cause
damage to animal and plant tissues. Gamma rays are absorbed by extremely dense materials like lead (Pb) and depleted uranium (U).
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| Gamma rays, x-rays, visible light, and Ultraviolet (UV) rays are all forms of electromagnetic radiation. The only difference is the frequency and hence the energy of the photons. Gamma rays are the most energetic.
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| The powerful nature of gamma rays have made them useful in the sterilizing of medical equipment by killing bacteria. They
are also used to kill bacteria and insects in foodstuffs, particularly meat and vegetables, to maintain freshness.
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| In spite of their cancer-causing properties, gamma rays are also used to treat some types of cancer. In the procedure called
gamma-knife surgery, multiple concentrated beams of gamma rays are directed on the growth in order to kill the cancerous cells.
The beams are aimed from different angles to focus the radiation on the growth while minimising damage to the surrounding tissues.
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| Gamma rays are also used for diagnostic purposes in nuclear medicine. Several gamma-emitting radioisotopes are used, one of
which is technetium-99m. When administered to a patient, a gamma camera can be used to form an image of the radioisotope's distribution by detecting
the gamma radiation emitted. Such a technique can be employed to diagnose a wide range of conditions (e.g. spread of cancer to the bones).
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