Download Cobalt isotopes in industry 60Co is used to irradiate food sources as

Stable
isotope
59
Co
Relative
atomic mass
58.933 194
Mole
fraction
1
Cobalt isotopes in industry
60
Co is used to irradiate food sources as a method of preserving food (Figure 1). The gamma
radiation from 60Co kills bacteria and other organisms that cause disease and spoilage of food (see
Figure 1). The use of radioactive compounds for preserving food is not always viewed positively.
Some individuals are concerned that harmful compounds will be produced during the irradiation
process. However, there is no evidence to support the fact that irradiation is a dangerous method of
food preservation [66, 102, 220-222]. Many medical products today are sterilized using gamma rays
from a 60Co source. This technique of sterilization is generally much cheaper and more effective than
steam-heat sterilization because it is a cold process. For example, it can be performed on packaged
items, such as disposable syringes. This sterilization technique is applicable to a wide range of heatsensitive items, such as powders, ointments, and solutions, as well as biological preparations, such as
bone, nerve, skin, etc., used in tissue grafts [66, 102, 220-222].
60
Co is also used in industrial radiography to detect structural flaws in metal parts. The radiation
can penetrate metals and the X-ray pattern produced by the radiating material can provide
information on its strength, composition, and other properties [66, 102, 220-222]. Because of the
above property, 60Co is also used in leveling devices and thickness gauges used to test welds and
castings [66, 102, 220-222].
Fig. 1: Plants growing in the gamma greenhouse at Brookhaven National Laboratory. The plants
are arranged in concentric rings around the radioactive 60Co source, which is in the pipe
extending into the floor (circa 1959) [223]. (Photo Source: LSF Magazine).
Cobalt isotopes in medicine
60
Co is a radioactive metal isotope that is used in cancer treatments by radiotherapy. When 60Co
undergoes radioactive decay, high-energy gamma rays (energies of 1.17 MeV and 1.33 MeV)
are emitted and can be used in brachytherapy to treat various types of cancer. Brachytherapy
(brachy- is Greek meaning “short distance”) is a method of radiation treatment in which sealed
sources are used to deliver a radiation dose at a distance of up to a few centimeters by surface,
intracavitary (insertion of the radioactive isotope in a body cavity), or interstitial (between cells)
application [66, 90, 220, 221, 224]. 60Co is used as a source of high-energy ionizing gamma
radiation that can be directed to cancer cells from a device outside the body (external
radiotherapy) [66, 90, 220, 221, 224].
60
Co (and sometimes 57Co and 58Co) is the key component of the Schilling test, which is a
method for determining whether a patient’s body is making and using vitamin B12 properly. The
cobalt isotope is used to label cobalt in vitamin B12 to monitor how the body processes this
essential vitamin [66, 90, 220, 221, 224].
57
Co delivers the smallest radiation dose of all the cobalt isotopes. As a result, it has been
used in the past for imaging and estimating organ size and location and in evaluating tumors of
the head and neck [66, 90, 220, 221, 224].
Glossary
atomic number (Z) – The number of protons in the nucleus of an atom.
brachytherapy – the treatment of cancer, especially prostate cancer, by the insertion of
radioactive implants directly into the tissue near the tumor. [return]
electron – elementary particle of matter with a negative electric charge and a rest mass of about
9.109 × 10–31 kg.
element (chemical element) – a species of atoms; all atoms with the same number of protons in
the atomic nucleus. A pure chemical substance composed of atoms with the same number of
protons in the atomic nucleus [703].
gamma rays (gamma radiation) – a stream of high-energy electromagnetic radiation given off
by an atomic nucleus undergoing radioactive decay. The energies of gamma rays are higher
than those of X-rays; thus, gamma rays have greater penetrating power.[return]
half-life (radioactive) – the time interval that it takes for the total number of atoms of any
radioactive isotope to decay and leave only one-half of the original number of atoms.
ionizing – pertaining to the process by which an atom, molecule, or substance acquires a
negative or positive charge. Commonly, one or more electrons are removed to give a negative
charge. [return]
isotope – one of two or more species of atoms of a given element (having the same number of
protons in the nucleus) with different atomic masses (different number of neutrons in the
nucleus). The atom can either be a stable isotope or a radioactive isotope. [return]
neutron – an elementary particle with no net charge and a rest mass of about 1.675 × 10–27 kg,
slightly more than that of the proton. All atoms contain neutrons in their nucleus except for
protium (1H).
proton – an elementary particle having a rest mass of about 1.673 × 10–27 kg, slightly less than
that of a neutron, and a positive electric charge equal and opposite to that of the electron. The
number of protons in the nucleus of an atom is the atomic number.
radioactive decay – the process by which unstable (or radioactive) isotopes lose energy by
emitting alpha particles (helium nuclei), beta particles (positive or negative electrons), gamma
radiation, neutrons or protons to reach a final stable energy state. [return]
radioactive isotope (radioisotope) – an atom for which radioactive decay has been
experimentally measured (also see half-life). [return]
radiography – an imaging technique that uses electromagnetic radiation other than visible light,
especially X-rays and gamma rays, to view the internal structure of non-uniform objects, such
as metal parts, welded pipes, and the human body. [return]
radiotherapy (radiation therapy) – the treatment of disease by means of radiation from
radioactive substances or X-rays. [return]
stable isotope – an atom for which no radioactive decay has ever been experimentally measured.
X-rays – electromagnetic radiation with a wavelength ranging from 0.01 to 10 nanometers—
shorter than those of UV rays and typically longer than those of gamma rays. [return]
References
66.
J. Peterson, McDonell, M., Haroun, L., Monette, F., Hildebrand, R.D., and Taboas, A.
Radiological and Chemical Fact Sheets to Support Health Risk Analyses for Contaminated
Areas. Prepared by Argonne National Laboratory Environmental Science Division in
collaboration with U.S. Department of Energy, Richland Operations Office and Chicago
Operations Office. 2014 Feb. 22.
http://www.remm.nlm.gov/ANL_ContaminantFactSheets_All_070418.pdf
90.
W. N. Association. Radioisotopes in Medicine. World Nuclear Association. 2014 Feb. 23.
http://www.world-nuclear.org/info/inf55.html
102. W. N. Association. Radioisotopes in Industry: Industrial Uses of Radioisotopes. World
Nuclear Association. 2014 Feb. 24. http://www.world-nuclear.org/info/inf56.html
220. R. S. o. Chemistry. Cobalt. Royal Society of Chemistry. 2014 Feb. 26.
http://www.rsc.org/chemsoc/visualelements/pages/pdf/cobalt.PDF
221. U. E. P. Agency. Cobalt. US Environmental Protection Agency. 2014 Feb. 26.
http://www.epa.gov/rpdweb00/radionuclides/cobalt.html
222. A. Government. Radioactive Sources: Use, Safety And Security. Australian Government.
2014 Feb. 25. http://www.arpansa.gov.au/pubs/regulatory/security/ansto_safety_security.pdf
223. In LSF Magazine, pp. 14 (2012).
224. W. S. D. o. Health. Cobalt-60. Washington State Department of Health. 2014 Feb. 26.
http://www.doh.wa.gov/Portals/1/Documents/Pubs/320-078_co60_fs.pdf
703. I. U. o. P. a. A. Chemistry. Compendium of Chemical Terminology, 2nd ed. (the "Gold
Book"). Blackwell Scientific Publications, Oxford (1997).