Applications of radioactivity

The principles of radioactivity and radioactive decay have wide-ranging applications in medicine, industry, the home, the arts and sciences, and electric power generation.

Medicine

Nuclear medicine

Nuclear medicine is a branch of medicine and medical imaging that uses the nuclear properties of matter in diagnosis and therapy. Many procedures in nuclear medicine use pharmaceuticals that have been labeled with radionuclides (radiopharmaceuticals). In diagnosis, radioactive substances are administered to patients and the radiation emitted is measured. The majority of these diagnostic tests involve the formation of an image using a gamma camera. Imaging may also be referred to as radionuclide imaging or nuclear scintigraphy. Other diagnostic tests use probes to acquire measurements from parts of the body, or counters for the measurement of samples taken from the patient. In therapy, radionuclides are administered to treat disease or provide palliative pain relief. For example, administration of Iodine-131 is often used for the treatment of thyrotoxicosis and thyroid cancer.

Radiotherapy

Radiation therapy (or radiotherapy) is the medical use of ionizing radiation as part of cancer treatment to control malignant cells. The radiation may be given in the form of external beam radiotherapy of high-energy electrons or X-rays, or it may come from radioactive sources placed inside the patient.

Radioactive tracers

Radioactive tracers are radioactive substances added in minute amounts to the reacting elements or compounds in a chemical process and traced through the process by appropriate detection methods, e.g., Geiger counter. Compounds containing tracers are often said to be tagged or labeled.

In medical applications, a radioactive atom can be attached to a molecule or more complex substance, which can then be used to examine a chemical reaction in a test tube, or it can be administered to a patient by ingestion or injection and subsequently be incorporated into a biochemical process. The radioactive emissions from the radioactive atom can be used to track (trace) the behavior of the labeled molecule or substance in biological processes by means of medical imaging

Industry and the Home

Radiation processing is the use of ionizing radiation to produce beneficial physical, chemical or biological effects on an industrial scale. Examples include:

  • The isotope 252Cf (a neutron emitter) is used in neutron activation analysis to inspect airline luggage for hidden explosives, to gauge the moisture content of soil and other materials, in bore hole logging in geology, and in human cervix-cancer therapy.
  • In paper mills, the thickness of the paper can be controlled by measuring how much beta radiation passes through the paper to a Geiger counter. The counter controls the pressure of the rollers to give the correct thickness.
  • Checking Welds. If a gamma source is placed on one side of the welded metal, and a photographic film on the other side, weak points or air bubbles will show up on the film.
  • Foodstuffs can be irradiated to extend shelf life or reduce the numbers of harmful bacteria.
  • Improve material properties, particularly in polymers, curing adhesives and resins, improvement of gemstones, wire and cable jacket curing, tire manufacture.
  • Smoke alarms contain a weak source made of Americium-241. Alpha particles are emitted that ionize the air, so that the air conducts electricity and a small current flows. If smoke enters the alarm, this absorbs the a particles, the current reduces, and the alarm sounds.

Radiation has many uses in agriculture. In plant research, radiation is used to develop new plant types to speed up the process of developing superior agricultural products. Insect control is another important application; pest populations are drastically reduced and, in some cases, eliminated by exposing male insects to sterilizing doses of radiation. Fertilizer consumption has been reduced through research with radioactive tracers. Radiation pellets are used in grain elevators to kill insects and rodents. Irradiation prolongs the shelf-life of foods by destroying bacteria, viruses, and molds.

Radioactive Dating

Radioactive dating, or radiometric dating is a technique used to date materials based on a knowledge of the decay rates of naturally occurring isotopes, and their current abundances. Many isotopes have been studied, probing a wide range of time scales. Radioactive dating is the principal source of information about the age of the Earth and rates of evolutionary change, and is used to estimate the age of once–living materials.

Power Generation

Nuclear power is a type of nuclear technology involving the controlled use of nuclear fission to release energy for work including propulsion, heat, and the generation of electricity. Nuclear energy is produced by a controlled nuclear chain reaction and creates heat—which is used to boil water, produce steam, and drive a steam turbine. The turbine can be used for mechanical work and also to generate electricity. As of 2007, nuclear power provided about 6% of the world's energy and 16% of the world's electricity, with the U.S., France, and Japan together accounting for 57% of all nuclear generated electricity.

Art Restoration

Nuclear science plays an important role in the art world. A technique known as X-ray fluorescence spectroscopy (or XRF), works by irradiating samples of materials using X-rays without destroying the analyzed material. At the same time, it can identify a vast number of elements simultaneously, making it an excellent way to "fingerprint" all kinds of materials. For example, XRF has been used to examine the tip of David’s nose, analyzing dust and dirt before Michelango’s masterpiece could be safely restored.

Restoration work on Cellini’s bronze statue of Perseus at the Uffizi Museum in Florence also benefited from insights gained using XRF. Examinations of Perseus’ right knee showed that the bronze alloy was composed of varying percentages of copper, tin, lead, antimony, iron and silver.

Clues from XRF results also can aid forensic scientists in solving crimes; for example, by determining if a paint pigment matches the artist’s original palette. Discovering the presence of a modern replacement for an old traditional pigment known to be used by a particular artist can provide evidence that a painting is a forgery.

Common radioisotopes and their uses

Americium-241: Used in many smoke detectors for homes and businesses to measure levels of toxic lead in dried paint samples, to ensure uniform thickness in rolling processes like steel and paper production, and to help determine where oil wells should be drilled
Cadmium-109: Used to analyze metal alloys for checking stock and sorting scrap
Calcium-47: Aid to biomedical researchers studying the cell function and bone formation of mammals.
Californium-252: Used to measure the mineral content of coal ash and to measure the moisture of materials stored in silos
Carbon-14: Used in research to ensure that potential new drugs are metabolized without forming harmful by-products.
Cesium-137: Used to treat cancers; to calibrate the equipment used to measure correct patient dosages of radioactive pharmaceuticals; to measure and control the liquid flow in oil pipelines; to tell researchers whether oil wells are plugged by sand; and to ensure the right fill level for packages of food, drugs and other products. (The products in these packages do not become radioactive.)
Chromium-51: Used in research in red blood cell survival studies.
Cobalt-57: Used in nuclear medicine to help physicians interpret diagnostic scans of patients' organs, and to diagnose pernicious anemia.
Cobalt-60: Used to sterilize surgical instruments; to improve the safety and reliability of industrial fuel oil burners; and to preserve poultry, fruits and spices.
Copper-67: When injected with monoclonal antibodies into a cancer patient, helps the antibodies bind to and destroy the tumor
Curium-244: Used in mining to analyze material excavated from pits and slurries from drilling operations.
Iodine-123: Widely used to diagnose thyroid disorders.
Iodine-129: Used to check some radioactivity counters in vitro diagnostic testing laboratories.
Iodine-131: Used to diagnose and treat thyroid disorders
Iridium-192: Used to test the integrity of pipeline welds, boilers and aircraft parts.
Iron-55: Used to analyze electroplating solutions.
Krypton-85: Used in indicator lights in appliances like clothes washers and dryers, stereos and coffeemakers; to gauge the thickness of thin plastics, sheet metal, rubber, textiles and paper; and to measure dust and pollutant levels.
Nickel-63: Used to detect explosives and as voltage regulators and current surge protectors in electronic devices
Phosphorus-32: Used in molecular biology and genetics research.

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