Gamma-rays, also known as gamma radiation, are one of seven forms of radiant energy in the electromagnetic spectrum. Electromagnetic energy traverses space in waves, and gamma-rays have a shorter wavelength and more energy than any other electromagnetic wave. Similar in nature to X-rays, gamma-rays occur naturally and travel great distances across the universe. Though modern science harnessed the power of gamma-rays to benefit mankind in many ways, they can be dangerous.
Radiation Therapy for Cancer
Radiation therapy, or radiation oncology, utilises gamma radiation to kill or control malignant tumours in the body. Gamma-rays damage the cancerous cells' DNA, causing them to die or reproduce more slowly. Often used in conjunction with surgery or chemotherapy, radiation therapy targets tumours with a focused beam of gamma-rays. However, gamma-rays kill both healthy cells and cancerous cells. Specialised radiation therapies such as brachytherapy and Gamma Knife surgery (which is not a surgery and does not use a knife) reduce the damage to healthy cells by minimising their exposure to gamma-rays.
Conventional X-rays of soft tissues often do not produce images that enable accurate diagnosis. Doctors may use specialised gamma-ray scanning equipment to produce a high-quality diagnostic image. Patients ingest liquids containing gamma-ray emitting substances; the scanner detects the electromagnetic rays in the body and creates three-dimensional diagnostic images of functional processes in the body. This procedure is known as Positron Emission Tomography, or a PET scan.
Cargo Container Scanning
U.S. Bureau of Customs and Border Protection statistics indicate that more than 11 million cargo containers enter U.S. seaports every year. Gamma-ray scanners inspect cargo containers to detect weapons and other contraband as part of an integrated program to increase the security of containerised cargo entering the U.S. from around the world.
Some foods, particularly poultry and produce, are exposed to radiation as a means of killing bacteria and other harmful food-borne pathogens. The process of irradiation is sometimes called cold-pasteurisation, and it reduces the incidence of food poisoning and spoilage. The food does not retain any radiation, nor does it come in direct contact with any radioactive substance.
Deep Space Exploration
NASA uses technology such as the Fermi Gamma-ray Space Telescope to map the Milky Way galaxy and "see" further into space than ever before. Gamma-ray detectors turn distant gamma-rays into signals that can then be formed into images. Data gathered from the Fermi telescope enables scientists to learn more about gamma-ray bursts, black-holes, pulsars and other deep space phenomena.
Dangers of Gamma-ray Exposure
Large doses of gamma-radiation can harm or alter healthy cells resulting in the growth of cancerous cells or tumours. Gamma radiation is the radiation primarily associated with nuclear explosions and accidents such as the Chernobyl Reactor in Ukraine and the Fukushima nuclear power plant in Japan following the 2011 earthquake. Incidents such as these produce gamma-ray emitting particles that contaminate the environment for many years.
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- National Cancer Institute: Radiation Therapy for Cancer
- Mayo Clinic: Positron Emission Tomography
- U.S. Environmental Protection Agency: Food Irradiation
- "Advanced Cargo Container Scanning Technology Development"; Victor Orphan, et al.
- NASA: Mission: Science-Gamma Rays
- University of Maryland Medical Center: Gamma Knife Surgery