Safety Code 34. Radiation Protection and Safety for Industrial X-Ray Equipment

Glossary

The following definitions apply to this Safety Code.

Accident. An event which leads to or could lead to unplanned or inadvertent irradiations of humans.

ALARA. Acronym for As Low As Reasonably Achievable. It is a concept that means the design and use of radiation sources and the practices associated therewith must be such as to ensure that exposures to radiation are kept as lowas reasonably achievable with social and economic factors taken into account.

Allied personnel. Safety personnel or other staff in the vicinity of radiography work areas of a facility.

Alpha particle. A helium nucleus made up of two neutrons and two protons. An alpha particle can be stopped in a piece of paper a few microns thick. It produces substantially more ions than an x ray or gamma ray or an electron and, therefore, the potential for cellular damage is greater.

Atom. Basic component of matter. It is the smallest part of an element that has all the chemical properties of that element. It consists of a nucleus and electrons around the nucleus.

Background radiation. Radiation arising from natural sources present in the environment, solar and cosmic radiation in outer space, and naturally occurring radioactive elements present in the atmosphere, the ground, building materials and the human body. The background radiation level varies from place to place. An individual residing in North America would incur an average radiation dose value of about 2.4 mSv (240 mrem) per year.

Binding energy. A general term that refers to the minimum energy required to remove a proton or a neutron or an electron from an atom.

Cabinet x-ray system. An x-ray system designed to contain an x-ray tube and generator, detectors and space for the examination of materials within an enclosure that is independent of existing architectural structures of a building except the floor on which it may be placed, provides radiation attenuation, and excludes personnel from its interior during generation of ionizing radiation.

Cancer. A general term used to indicate any of the various types of malignant neoplasms.

Certified industrial radiographer. An industrial radiographer qualified in accordance with the national standards of Canada or equivalent; the Canadian General Standards Board standards are national. An individual who is a certified exposure device operator in accordance with Canadian Nuclear Safety Commission regulations is also considered a certified industrial radiographer for the purposes of this Safety Code.

Collimator. A shield placed in the path of a primary beam to restrict the size of that radiation beam.

Congenital. Existing at birth or acquired during in-utero development and not through heredity.

Controlled area. Adefined area within which industrial radiography is carried out and where dose levels are likely to exceed 0.3 mSv in a week. It shall be under the supervision of a radiation safety officer (RSO).

DNA. Deoxyribonucleic acid. The genetic material of cells.

Deterministic effect. An adverse biological effect for which a threshold dose generally exists. The severity of the effect increases with dose. Below the threshold dose the effect is not detected clinically.

Dose. The quotient, expressed in gray, of the energy absorbed through exposure to ionizing radiation and the mass of the body or that part of the body that absorbed the radiation. (1 gray (Gy) = 100 rad.)

Dose equivalent. The product of dose and a radiation weighting factor. For x rays and gamma rays the radiation weighting factor is 1. Dose equivalent can be expressed in rem. 1 rem ~ 1 rad for soft tissue. In 1990, the ICRP proposed using the term 'equivalent dose' instead of dose equivalent.

Dose limit: Applies in relation to persons and refers to the limit on effective dose or equivalent dose specified in Appendix II.

Effective dose. It is the sum of the products, obtained by multiplying the equivalent dose of radiation received by each tissue or organ listed in Table 3 of Appendix II and the corresponding tissue or organ weighting factor given in column 2 of the same Table. The unit is the seivert (Sv).

Electromagnetic radiation. Radiation considered as a wave of electric and magnetic energy traveling through a medium. In space it travels at the speed of light. It includes x rays and gamma rays.

Electron beam welder. A machine that produces high-intensity focused electron beams for melting and bonding materials in vacuum conditions.

Embryo. A developing human organism from conception to the end of the sixth week of gestation.

Ensure. To make certain.

Equivalent dose. It is the product of dose and a radiation weighting factor expressed in seivert. It is the term recommended by the ICRP in 1990 to replace the dose equivalent. (One seivert (Sv) = 100 rem.)

Facility. A site where industrial radiography is carried out.

Failsafe. Having the property that any failure causes an action or actions which always result in a safe situation.

Flash x-ray source. A device capable of producing extremely high levels of x rays within very short time frames in the order of micro-seconds or less. Such sources are used for studying dynamic events associated with ballistics, explosives, implosions or detonators.

Gamma ray. High-energy, short wavelength electromagnetic radiation emitted in the radioactive decay of an unstable atom.

Gray. International Standard (SI) unit for dose. 1 gray (Gy) = 100 rad.

High radiation field. A qualitative indication of the equivalent dose rates that exist in a particular area. Areas with equivalent dose rates in excess of 1 mSvper hour should be regarded as high radiation fields.

IAEA. International Atomic Energy Agency. An agency formed in 1954 within the United Nations to create and apply international safe - guards consistent with the peaceful uses of atomic energy. It has issued internationally agreed radiation protection standards based on the recommendations of the ICRP.

ICRP. International Commission on Radiological Protection. An independent group of experts from a wide range of scientific disciplines which have published recommendations for the protection of radiation workers and the public against ionizing radiation for more than 50 years.

Ionizing radiation. Radiation that has enough energy to dislodge an electron of an atom. It includes x rays, gamma rays, alpha particles, neutrons, protons and electrons.

Industrial radiographer. A person having the academic and professional training to use radiation equipment for industrial radiography. A certified industrial radiographer is within the scope of this definition.

Industrial radiography. Examination of the structure of materials by nondestructive methods in which ionizing radiation is used to make radiographic images.

Industrial x-ray equipment. X-ray machines used for industrial radiography and electron beam welders used for melting and bonding materials.

Industrial x-ray equipment owner. A person, organization or institution having title to or administrative control of one or more permanent installations or radiation sources used f or industrial radi ography.

Isotope. Atoms of the same element but different mass numbers. The mass number refers to the sum of the number of protons and neutrons in the nucleus of the atom.

Interlock. A device that precludes radiation exposure to an individual by preventing entry to a hazardous area or by automatically removing the hazard.

Ion. An atom or group of atoms that carries a positive or negative charge as a result of having lost or gained one or more electrons.

Irradiation. Exposure of a living being or matter to x-radiation or electrons.

Leakage radiation. All radiation, except the primary radiation, coming from an ionizing radiation source.

Leukemia. A disease in humans characterized by an abnormal increase in the number of white blood cells in tissue or blood.

Malignant. Resistant to treatment and occurring in severe form and frequently fatal.

MeV. Million electron volts. The kinetic energy acquired by an electron in traveling through a potential difference of 1 million volts.

Muon. A particle that has a mass about one-tenth that of a proton or about 200 times heavier than an electron.

MV. The potential to which accelerating particles is subjected.

Neutron. One of the three basic particles of all atoms heavier than hydrogen. Neutrons have no electrical charge, are located in the nucleus of the atom and each has a mass approximately equal to a proton.

Nuclide. A general term used to describe a family of isotopes.

Occupational. The exposure of an individual to ionizing radiation incurred in the course of employment by virtue of the normal duties of the individual in the workplace.

Other user. An individual age 18 or older who uses industrial x-ray equipment for a purpose other than industrial radiography or material fusion (melting and bonding).

Permanent installation. A shielded enclosure in a fixed location.

Photon. A quantum of electromagnetic radiation equal to a constant (Planck's constant which is: 6.61 x 10 ^-34 J s ) times the frequency of radiation (unit is the hertz), applicable to x rays and gamma rays.

Primary radiation. Radiation that emanates from a radiation source or target and passes through the radiation source assembly via a collimator or other beam shaping device. A synonym for primary beam.

Proton. One of the three basic particles of an atom. Protons have a positive electrical charge, are located in the nucleus of the atom and each has a mass approximately equal to a neutron.

Rad. Unit of absorbed dose. One rad = 100 erg of energy absorbed per gram of material. 1 rad equals 1 centigray.

Radiation equipment owner. A person, organization, or institution having title to or administrative control over one or more facilities having source(s) of ionizing radiation.

Radiation protection adviser. A person having the specialized knowledge, training and experience necessary to perform the task of giving advice and guidance in ionizing radiation safety in a competent and professional manner.

RSO. Radiation Safety Officer. An individual having the responsibility for the overall radiation safety program on behalf of the owner of the industrial x-ray equipment and meeting the requirements of Section 2.2 of this Safety Code. ( An individual recognized as an RSO in accordance with CNSCrequirements would suffice for purposes of this Safety Code.)

Radiation source. A sealed gamma ray source or other source emitting ionizing radiation.

Radioactive. Release of energy in the form of particles or gamma rays emitted by the disintegration of the nuclei of atoms.

Radioactive isotope. Element that emits ionizing radiation when it decays.

Radiography. Use of ionizing radiation to produce radiographic images on film, fluorescent material or an image display device.

Radionuclide. Any species of an atom that is radioactive.

Regulatory authority. An authority designated or otherwise recognized by a government for regulatory purposes in connection with protection and safety.

Roentgen. Unit of exposure to x rays or gamma rays having energies < 3 MeV. One roentgen = 2.58 x 10 ^-4 coulomb per kilogram of air.

Secondary radiation. Ionizing radiation emitted by matter as a result of the interaction of primary radiation with that matter.

Sell. An offer for sale, or advertising a product for the purpose of sale, or delivering or distributing a product for sale or lease.

Service personnel. Specifically trained persons, authorized by the industrial x-ray equipment manufacturer or its agent(s), to undertake service functions.

Shielded enclosure. An enclosed space that contains a radiation source and is engineered with safety components to provide adequate shielding and protection from ionizing radiations.

Shielding. Material used to protect people or living things or items from ionizing radiation.

Sievert. Unit of equivalent dose. One sievert (Sv) = 100 rem.

Stochastic effects. An adverse biological effect for which the probability of occurrence increases with dose but the severity does not depend on the magnitude of the absorbed dose. There is no dose threshold for such effects to occur.

Stray radiation. The sum of secondary and leakage radiations.

Supervised area. Any area not designated a controlled area but which requires the occupational exposure conditions to be kept under review.

Survey meter. Aportable instrument that measures exposure or dose or equivalent dose rate.

Target. Part of an x-ray tube or material surface onto which is directed a beam of accelerated particles to produce x rays.

X rays. Electromagnetic radiation that is more energetic than visible light.

X-radiation. A beam of x rays.