What Types of Radiation Are There
Content
What Types of Radiation Are There?
The radiation one typically encounters is one of four types: alpha radiation, beta radiation, gamma radiation, and x radiation. Neutron radiation is also encountered in nuclear power plants and high-altitude flight and emitted from some industrial radioactive sources. 1. Alpha Radiation Alpha radiation is a heavy, very short-range particle and is actually an ejected helium nucleus. Some characteristics of alpha radiation are:
o o o
o o o o
Most alpha radiation is not able to penetrate human skin. Alpha-emitting materials can be harmful to humans if the materials are inhaled, swallowed, or absorbed through open wounds. A variety of instruments has been designed to measure alpha radiation. Special training in the use of these instruments is essential for making accurate measurements. A thin-window Geiger-Mueller (GM) probe can detect the presence of alpha radiation. Instruments cannot detect alpha radiation through even a thin layer of water, dust, paper, or other material, because alpha radiation is not penetrating. Alpha radiation travels only a short distance (a few inches) in air, but is not an external hazard. Alpha radiation is not able to penetrate clothing.
Examples of some alpha emitters: radium, radon, uranium, thorium. 2. Beta Radiation Beta radiation is a light, short-range particle and is actually an ejected electron. Some characteristics of beta radiation are:
o o
o o
o
Beta radiation may travel several feet in air and is moderately penetrating. Beta radiation can penetrate human skin to the "germinal layer," where new skin cells are produced. If high levels of beta-emitting contaminants are allowed to remain on the skin for a prolonged period of time, they may cause skin injury. Beta-emitting contaminants may be harmful if deposited internally. Most beta emitters can be detected with a survey instrument and a thinwindow GM probe (e.g., "pancake" type). Some beta emitters, however, produce very low-energy, poorly penetrating radiation that may be difficult or impossible to detect. Examples of these difficult-to-detect beta emitters are hydrogen-3 (tritium), carbon-14, and sulfur-35. Clothing provides some protection against beta radiation.
Examples of some pure beta emitters: strontium-90, carbon-14, tritium, and sulfur-35.
3. Gamma and X Radiation Gamma radiation and x rays are highly penetrating electromagnetic radiation. Some characteristics of these radiations are: o Gamma radiation or x rays are able to travel many feet in air and many inches in human tissue. They readily penetrate most materials and are sometimes called "penetrating" radiation. o X rays are like gamma rays. X rays, too, are penetrating radiation. Sealed radioactive sources and machines that emit gamma radiation and x rays respectively constitute mainly an external hazard to humans. o Gamma radiation and x rays are electromagnetic radiation like visible light, radiowaves, and ultraviolet light. These electromagnetic radiations differ only in the amount of energy they have. Gamma rays and x rays are the most energetic of these. o Dense materials are needed for shielding from gamma radiation. Clothing provides little shielding from penetrating radiation, but will prevent contamination of the skin by gamma-emitting radioactive materials. o Gamma radiation is easily detected by survey meters with a sodium iodide detector probe. o Gamma radiation and/or characteristic x rays frequently accompany the emission of alpha and beta radiation during radioactive decay.
Examples of some gamma emitters: iodine-131, cesium-137, cobalt-60, radium-226, and technetium-99m.
USES OF RADIATIONS
In public health care, radiation can be used to examine and treat patients. Examinations are X-ray or isotope examinations. In examinations or procedures that use radiation, care is taken to ensure that radiation exposure to the patient is kept to a minimum. In treating cancer, large doses of radiation are used to destroy diseased tissue. In industry, radiation is beneficial in quality control of materials, measuring the level of containers, or monitoring the thickness or consistency of paper, for example. Devices which monitor industrial processes consist of radiation sources and detectors. When the material between the radioactive source and the detector changes thickness or density, the level of radiation detected also changes. The process can be controlled by weakening or strengthening the signal from the detector. Industrial radiography is a method of non-destructive testing, used to check for flaws in metal structures and welding seals, among others. The principle is the same as in medical imaging: radiation passes through the object to be tested and exposes the X-ray film placed behind it. Dark patches in the developed film reveal flaws. Radiography devices create radiation using either X-ray machines, or for thicker material, a gamma source or linear accelerator.
Radioactive isotopes are used as tracers in many biochemical and physiological examinations. The path of material marked with tracers is monitored with an activity determination. Radioactive isotopes of carbon and hydrogen can be used to examine the path of nutrients into plants, for example. Practical applications for non-ionising radiation are, among others, lasers, microwave ovens, solariums, mobile telephones, MRI devices in the medical field, and industrial heaters.
Uses of radiation and their comparative portions.
Radiation is used in about 1500 locations and 9000 individual radiation sources or devices are in use. Dental X-ray machines are not included in these figures. There are about 5000 of these used in 2000 locations. The field in which the subatomic fragments emitted in radioactive decay (alpha-, beta-, gamma-rays) or produced by high-voltage accelerators (electrons, protons, x-rays) are applied to the problems of science, engineering, industry, and medicine. The techniques are extraordinarily versatile and sensitive and are basically inexpensive. A disadvantage that limits the range and extent of these applications is the health hazard that may be involved. Tracer applications are based on two principles. First is the chemical similarity of radioactive atoms and other atoms of the same element. Periodically a few of the radioactive atoms decay, emitting some penetrating subatomic fragments that can be detected one by one, usually through their ability to cause ionization. Thus the movement of a particular element can be followed through various chemical, physical, and biological steps. The second principle involves the characteristic half-life and nature of the emitted fragments. This makes a radioactive species unique and thereby detectable above a background of radioactive emitters associated with elements. For discussions of radioisotope techniques relating to tracer methodology.
Penetration and scattering applications arise from the fact that subatomic fragments can penetrate a thick section of a material, and yet a small fraction of the incident particles can be backscattered by a relatively thin section. The oldest application of the penetrating properties of energetic ionizing photons is radiography. An extension of this technique is autoradiography. Since World War II the penetration and scattering properties of beta- and gamma-rays have been applied in industry in the form of thickness gages. See also Autoradiography; Radiography. The absorption of small amounts of energy from ionizing particles and ionizing photons has chemical effects that have been the basis of several practical applications. The oldest application of this principle is radiation therapy. For example, in cancer therapy the local affected areas are irradiated by external beams of gammas from cobalt-60 or of radiation from accelerators. Radioactive sources have also been administered internally to induce beneficial biochemical reactions in patients afflicted with various ailments. See also Isotopic irradiation; Radiology. A related area is the radiation sterilization of biomedical supplies. The advantages to this method of biochemical destruction of microscopic life are that (1) unlike steam sterilization, it can be performed at low temperatures on plastics and other thermally unstable materials, and (2) unlike germicidal gases, ionizing radiation can reach every point in the treated product. Radiation-sterilized objects are not radioactive. The radiation preservation of food is an area of considerable promise. Small doses can inhibit sprouting in potatoes, kill insects in wheat, and sterilize pork products but practical applications have been sharply limited due to a cautious role by regulatory authorities in approving such procedures. Kinetic energy of emissions in radioactive decay can be converted to useful forms of light, heat, and electricity. See also Luminous paint; Nuclear battery.
SUBMITTED BY: Mr. Rodolfo A. FRigillana
Submitted to: Mr.
The radiation one typically encounters is one of four types: alpha radiation, beta radiation, gamma radiation, and x radiation. Neutron radiation is also encountered in nuclear power plants and high-altitude flight and emitted from some industrial radioactive sources. 1. Alpha Radiation Alpha radiation is a heavy, very short-range particle and is actually an ejected helium nucleus. Some characteristics of alpha radiation are:
o o o
o o o o
Most alpha radiation is not able to penetrate human skin. Alpha-emitting materials can be harmful to humans if the materials are inhaled, swallowed, or absorbed through open wounds. A variety of instruments has been designed to measure alpha radiation. Special training in the use of these instruments is essential for making accurate measurements. A thin-window Geiger-Mueller (GM) probe can detect the presence of alpha radiation. Instruments cannot detect alpha radiation through even a thin layer of water, dust, paper, or other material, because alpha radiation is not penetrating. Alpha radiation travels only a short distance (a few inches) in air, but is not an external hazard. Alpha radiation is not able to penetrate clothing.
Examples of some alpha emitters: radium, radon, uranium, thorium. 2. Beta Radiation Beta radiation is a light, short-range particle and is actually an ejected electron. Some characteristics of beta radiation are:
o o
o o
o
Beta radiation may travel several feet in air and is moderately penetrating. Beta radiation can penetrate human skin to the "germinal layer," where new skin cells are produced. If high levels of beta-emitting contaminants are allowed to remain on the skin for a prolonged period of time, they may cause skin injury. Beta-emitting contaminants may be harmful if deposited internally. Most beta emitters can be detected with a survey instrument and a thinwindow GM probe (e.g., "pancake" type). Some beta emitters, however, produce very low-energy, poorly penetrating radiation that may be difficult or impossible to detect. Examples of these difficult-to-detect beta emitters are hydrogen-3 (tritium), carbon-14, and sulfur-35. Clothing provides some protection against beta radiation.
Examples of some pure beta emitters: strontium-90, carbon-14, tritium, and sulfur-35.
3. Gamma and X Radiation Gamma radiation and x rays are highly penetrating electromagnetic radiation. Some characteristics of these radiations are: o Gamma radiation or x rays are able to travel many feet in air and many inches in human tissue. They readily penetrate most materials and are sometimes called "penetrating" radiation. o X rays are like gamma rays. X rays, too, are penetrating radiation. Sealed radioactive sources and machines that emit gamma radiation and x rays respectively constitute mainly an external hazard to humans. o Gamma radiation and x rays are electromagnetic radiation like visible light, radiowaves, and ultraviolet light. These electromagnetic radiations differ only in the amount of energy they have. Gamma rays and x rays are the most energetic of these. o Dense materials are needed for shielding from gamma radiation. Clothing provides little shielding from penetrating radiation, but will prevent contamination of the skin by gamma-emitting radioactive materials. o Gamma radiation is easily detected by survey meters with a sodium iodide detector probe. o Gamma radiation and/or characteristic x rays frequently accompany the emission of alpha and beta radiation during radioactive decay.
Examples of some gamma emitters: iodine-131, cesium-137, cobalt-60, radium-226, and technetium-99m.
USES OF RADIATIONS
In public health care, radiation can be used to examine and treat patients. Examinations are X-ray or isotope examinations. In examinations or procedures that use radiation, care is taken to ensure that radiation exposure to the patient is kept to a minimum. In treating cancer, large doses of radiation are used to destroy diseased tissue. In industry, radiation is beneficial in quality control of materials, measuring the level of containers, or monitoring the thickness or consistency of paper, for example. Devices which monitor industrial processes consist of radiation sources and detectors. When the material between the radioactive source and the detector changes thickness or density, the level of radiation detected also changes. The process can be controlled by weakening or strengthening the signal from the detector. Industrial radiography is a method of non-destructive testing, used to check for flaws in metal structures and welding seals, among others. The principle is the same as in medical imaging: radiation passes through the object to be tested and exposes the X-ray film placed behind it. Dark patches in the developed film reveal flaws. Radiography devices create radiation using either X-ray machines, or for thicker material, a gamma source or linear accelerator.
Radioactive isotopes are used as tracers in many biochemical and physiological examinations. The path of material marked with tracers is monitored with an activity determination. Radioactive isotopes of carbon and hydrogen can be used to examine the path of nutrients into plants, for example. Practical applications for non-ionising radiation are, among others, lasers, microwave ovens, solariums, mobile telephones, MRI devices in the medical field, and industrial heaters.
Uses of radiation and their comparative portions.
Radiation is used in about 1500 locations and 9000 individual radiation sources or devices are in use. Dental X-ray machines are not included in these figures. There are about 5000 of these used in 2000 locations. The field in which the subatomic fragments emitted in radioactive decay (alpha-, beta-, gamma-rays) or produced by high-voltage accelerators (electrons, protons, x-rays) are applied to the problems of science, engineering, industry, and medicine. The techniques are extraordinarily versatile and sensitive and are basically inexpensive. A disadvantage that limits the range and extent of these applications is the health hazard that may be involved. Tracer applications are based on two principles. First is the chemical similarity of radioactive atoms and other atoms of the same element. Periodically a few of the radioactive atoms decay, emitting some penetrating subatomic fragments that can be detected one by one, usually through their ability to cause ionization. Thus the movement of a particular element can be followed through various chemical, physical, and biological steps. The second principle involves the characteristic half-life and nature of the emitted fragments. This makes a radioactive species unique and thereby detectable above a background of radioactive emitters associated with elements. For discussions of radioisotope techniques relating to tracer methodology.
Penetration and scattering applications arise from the fact that subatomic fragments can penetrate a thick section of a material, and yet a small fraction of the incident particles can be backscattered by a relatively thin section. The oldest application of the penetrating properties of energetic ionizing photons is radiography. An extension of this technique is autoradiography. Since World War II the penetration and scattering properties of beta- and gamma-rays have been applied in industry in the form of thickness gages. See also Autoradiography; Radiography. The absorption of small amounts of energy from ionizing particles and ionizing photons has chemical effects that have been the basis of several practical applications. The oldest application of this principle is radiation therapy. For example, in cancer therapy the local affected areas are irradiated by external beams of gammas from cobalt-60 or of radiation from accelerators. Radioactive sources have also been administered internally to induce beneficial biochemical reactions in patients afflicted with various ailments. See also Isotopic irradiation; Radiology. A related area is the radiation sterilization of biomedical supplies. The advantages to this method of biochemical destruction of microscopic life are that (1) unlike steam sterilization, it can be performed at low temperatures on plastics and other thermally unstable materials, and (2) unlike germicidal gases, ionizing radiation can reach every point in the treated product. Radiation-sterilized objects are not radioactive. The radiation preservation of food is an area of considerable promise. Small doses can inhibit sprouting in potatoes, kill insects in wheat, and sterilize pork products but practical applications have been sharply limited due to a cautious role by regulatory authorities in approving such procedures. Kinetic energy of emissions in radioactive decay can be converted to useful forms of light, heat, and electricity. See also Luminous paint; Nuclear battery.
SUBMITTED BY: Mr. Rodolfo A. FRigillana
Submitted to: Mr.
