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Ionizing radiations are increasingly used in a variety of applications in medicine, research and industry because of their known benefits to society. One important industrial application utilizes various sources of ionizing radiations to investigate the integrity of structures or components through radiographic images, a practice generally referred to as nondestructive radiography or industrial radiography. Industrial radiography to date is an established practice that provides benefits concurrent with radiation risks. The radiation protection objective, therefore, is to keep the risks as low as reasonably achievable (ALARA) while maximizing benefits.
Guidelines for ionizing radiation protection have been in existence for more than 60 years and have been subject to numerous revisions in that time. One authoritative international standard-setting organization is the International Commission on Radiological Protection (ICRP). In 1990, the ICRP reaffirmed its system of radiological protection aimed at reducing the radiation risks associated with ionizing radiation use, and recommended lower dose limits for radiation workers and the publicFootnote 1. The objectives of that system with respect to radiation exposure are twofold: to prevent the occurrence of deterministic effects, and to reduce the incidence of stochastic effects. Sharing these same goals, the International Atomic Energy Agency (IAEA) revised and updated its guidance documentsFootnote 2,Footnote 3 that not only reflect the 1990 recommendations of the ICRP, but also aim to lower ionizing radiation risks while not limiting the beneficial uses of ionizing radiation. The ICRP and IAEA publications are influential internationally and are used by a large number of countries to develop national regulations for radiation protection and safety.
This document is one in a series of Safety Codes published by Health Canada in accordance with Treasury Board Hazardous Substances DirectiveFootnote 4 to promote radiation protection and safety in the federal workplace. This Safety Code draws on the ICRP and IAEA objectives, concepts and recommendations, and provides advisory information and guidance on radiation protection and safety specific to industrial x-ray equipment. It supersedes Safety Code 27 and is intended for federal facilities. Thus, facilities subject to the Canada Labor Code Part II, Occupational Health and Safety LegislationFootnote 5 shall comply with the requirements of this Safety Code. This Safety Code comprises an Introduction, the Management of Radiation Protection and Safety, Requirements for Industrial X-ray Equipment, Additional Guidance, References, Glossary and Appendices. The Introduction provides a background on industrial x-ray equipment and radiation hazards, and indicates the intent and scope of the Safety Code. The Management of Radiation Protection and Safety Section specifies the responsibilities of stakeholders which are key in the management of radiation protection and safety relevant to industrial x-ray equipment. The section on Requirements for industrial X-ray Equipment specifies what is needed for regulatory compliance of equipment, for permanent and temporary work sites, and for on-site evaluations. Additional Guidance information is included for non-radiography use of industrial x-ray equipment, personnel monitoring, survey meters, emergency procedures, resale and disposal. References are provided as well as a Glossary and Appendices. The information and guidance provided in this Safety Code would be of interest to regulatory authorities, industrial x-ray equipment manufacturers, owners, operators, organizations or radiographers carrying out industrial radiography, and clients responsible for hiring such organizations.
This Safety Code may be adopted for use elsewhere. Facilities under provincial or territorial jurisdiction are advised to consult their appropriate agency for information and guidance on radiation protection and safety, since statutes and requirements could differ from one jurisdiction to the other. Relevant (provincial/territorial) contact information is available at a Health Canada websiteFootnote 6.
Given the diverse applications of industrial radiography, it is not possible to foresee all work situations; therefore, it is plausible that unexpected problems may occasionally occur and the guidance in this Safety Code may be insufficient to address them. For such situations, consultation with the appropriate regulatory authority is advised.
This Safety Code was drafted, prepared and finalized by H.P. Maharaj in accordance with Health Canada review and publishing criteria. Interpretation of requirements or guidance in this document should be directed to the attention of:
Head, Nonmedical X-Rays,
PL 6301A,
775 Brookfield Road,
Ottawa, Ontario,
K1A1C1
(Facsimile number: (613) 941-1734).
Acknowledgment is extended to the following contributors for their comments and/or suggestions towards improvement and clarity of this document:
Machines have been specifically designed to generate x rays for the purpose of investigating the integrity of structures or components through radiographic images; this application is called nondestructive radiography or industrial radiography. Three types of ionizing radiation sources are typically available for such purposes:
Industrial radiography machines which are x-ray tube based can produce dose rates in air of about 2 Gy per minute at one metreFootnote 7. They may be highly portable or mobile and convenient for use at temporary job sites. Sometimes they can be operated by a single worker in a wide range of conditions such as at aircraft hangers, pipeline construction and deployment, fabrication facilities, offshore platform operations, bridges, or construction sites. At temporary work sites, the working conditions coupled with frequent manipulation of such high-intensity radiation sources present much potential for radiation exposure to occur. Both the worker(s) and other persons proximal to the work area can be exposed to high radiation fields which, potentially, can result in radiation accidents that could lead to serious personal injuries or death. In other work situations, x-ray tube based devices may be installed in a shielded enclosure equipped with safety components which significantly reduce radiation risks. To date industrial radiography is an established practice that provides benefits concurrent with radiation risks.
In another industrial application there are systems specifically designed to focus intense beams of high-energy electrons that melt and bond metals under vacuum conditions, and these electron-metal interactions can produce x rays as a byproduct of the bonding process. Such systems are called electron beam welders. By design, electrons are emitted from heated filaments and accelerated to several hundred kilovolts before impacting on metallic materials which are generally placed in a vacuum. In some designs, however, the electron beam passes through a series of orifices, each of which is individually evacuated while the target material is positioned within close range (few centimeters) of the last orifice. Beam currents and high voltages are typically in the range of 20-200 mA and 120- 450 kV, respectively. A device operating at 150 kV and 50 mA, for example, would yield an estimated electron dose rate in air of ~ 0.5 Gy per second at 50 cm, while the scattered x-ray radiation field at 1 metre would approximate 1 Gy per hour for a 1-cm primary electron beam incident on a copper targetFootnote 8. The welding process requires the use of highly focused beams, a requirement that not only reduces the number of electrons striking the metals being bonded but also lowers the contribution of byproduct x rays potentially scattered. The operation of electron beam welders presents a potential for exposure to x rays and electrons.
Collectively, in this document, x-ray tube based machines used for industrial radiography and electron beam welders are classed as "industrial x-ray equipment."
They present potential risks of exposure to x rays and electrons. The radiation protection objective, therefore, is to keep the risks ALARA while maximizing benefits.
X rays and electrons are types of ionizing radiation. In general when ionizing radiation traverses matter the interaction is probabilistic, that is, there may or may not be an interaction. In the case of a medium composed of cells of living organisms, the interaction with individual cells may be direct or indirect. At the cellular level, direct interaction with DNA or other constituents can cause damage. In the indirect mechanism, reactive ions are formed due to the breakdownof the water molecules present in the cells; such ions can interact with any cellular constituent thereby leading to potential damage. Various possibilities exist for the fate of cells exposed to ionizing radiation:
"threshold". dose for each organ and tissue above which functional impairment will manifest as a clinically observable adverse outcome. Exceeding the threshold dose increases the level of harm. Such outcomes are called deterministic effects and occur at high doses.
Germ cells are present in the ovaries and testes and are responsible for reproduction. Should they be modified by radiation, hereditary effects may occur in the progeny of the individuals exposed to radiation. Radiation-induced hereditary effects have not been observed in human populations yet they have been demonstrated in animals. Exposure of the embryo or fetus to ionizing radiation could increase the risk of leukemia in infants and, during certain periods in early pregnancy, may lead to mental retardation and congenital malformations if the amount of radiation is sufficiently high.
Exposure to ionizing radiations has the potential to cause early or late adverse health effects. This is why the radiation risks associated with industrial x-ray equipment need to be managed
The objective of this Safety Code is to present information for the radiation protection and safety of individuals operating, using and servicing industrial radiography x-ray equipment at permanent installations or at temporary job sites, and of persons proximal to such work areas. The owners of industrial x-ray equipment, the organizations or individuals carrying out industrial radiography, and clients who hire such organizations or individuals are responsible for ensuring that all safety procedures are followed and that the work is done in a manner that does not pose undue risks to any person.
This document provides basic requirements and guidance intended for the radiation protection and safety of industrial radiographers, other users, service personnel and the public. It does not discuss industrial radiography techniques or electron beam welding processes or other requirements (e.g., electrical or explosive).
This Safety Code applies specifically to industrial x-ray equipment operating at energies up to 6 MeV for use in industrial radiography and in material melting-and-bonding applications. It therefore covers x-ray tube based equipment, electron beam welders and low energy (≤ 6 MV) accelerators.
It may have limited application in x-ray photon-based scanning systems used for cargo surveillance purposes. The characteristics of such systems include:
This Safety Code excludes:
Some of the terms used in this document are defined in the glossary.
Mitigation of radiation risks associated with the use of industrial x-ray equipment requires the collective action of various stakeholders: the regulatory authority, the equipment manufacturers, equipment owners, equipment operators, equipment servicing personnel, organizations carrying out industrial radiography, clients responsible for hiring such organizations, and the public. The stakeholders' responsibilities and functions are indicated below.
The primary functions of the regulatory authority (Health Canada) are: to develop standards and provide guidance; to verify, ensure and enforce compliance with the standards and safety requirements; and to conduct evaluations of industrial x-ray equipment and of organizations carrying out radiography. In accord with its health protection mandate, the regulatory authority has the powers to enforce compliance with this Safety Code, to make or authorize measurements that would facilitate evaluation for compliance with the requirements of this Safety Code or to require an operating organization or facility to modify or correct any procedure, practice, system or component to ensure safety. It can issue directives prohibiting use of industrial x-ray equipment, depending on the hazards and risks presented by deviations of procedures or by safety violations, and can annul the confirmation of registration.
Only products that are compliant with the RED ActFootnote 9 shall be procured. The owner of industrial x-ray equipment is ultimately responsible for the radiation safety of that equipment, and for ensuring that it is used in accordance with all legislation and regulations, including conformance with other safety standards (e.g., electrical, explosive) that might be applicable for the safe use of the equipment in the intended workplace. This responsibility requires a strong commitment to safety by the owner of the industrial x-ray equipment, demonstrated by the establishment and use of a radiation safety program.
The owner shall appoint a Radiation Safety Officer (RSO) to oversee and implement the radiation safety program at each facility in which industrial radiography is carried out, and shall provide adequate financial and physical resources for the incumbent duties and actions. A facility-designated RSO, by appointment to the position, is empowered to undertake necessary supervision of radiation protection activities, stop unsafe practices, implement safety directives and enforce prohibitions issued by the regulatory authority pursuant to this Safety Code. An RSO shall be a certified industrial radiographer at the NDT Level 1, or higher, as described in Section 2.2.1.12. of this Safety Code.
The owner of industrial x-ray equipment that is to be operated in a facility under federal jurisdiction shall ensure that the equipment is duly registered as described in Section 3.2 of this Safety Code and that there is a valid confirmation of registration before the equipment is used. A federal facility that operates industrial x-ray equipment without a valid confirmation of registration is in contravention of legislationFootnote 5.
Prior to procurement of industrial x-ray equipment, the RSO must receive written confirmation from the equipment manufacturer or its authorized marketing agent that the product complies with the RED Act (refer to Section 4.1 of this Safety Code). The onus is on the equipment manufacturer to show proof of or demonstrate regulatory compliance. Only products that are compliant with the RED Act shall be procured. The RSO must ensure that (i) the industrial x-ray equipment and the facility(ies) in which it will be in use meet all applicable radiation safety and regulatory requirements in this Safety Code, including conformance with other applicable standards (e.g., electrical, explosive); and (ii) industrial radiography is performed in accordance with safety procedures consistent with those of the practice. In a case for which noncompliance is identified after the equipment has left the manufacturer's premises, guidance to ensure regulatory compliance of the equipment is given in Section 2.4 of this Safety Code.
The specific and incumbent actions required of an RSO are:
A certified industrial radiographer is an individual meeting the requirements as described in Section 2.2.1.12. of this Safety Code. The individual has a responsibility to carry out the radiography work in accordance with instructions and defined operating and safety procedures to ensure his or her protection and that of others. It is therefore imperative that there be strict adherence of the safety instructions, procedures and precautions provided in the operating manual of the specific industrial x-ray equipment to be used. The individual shall adopt an overall safety philosophy when doing industrial radiography and, in this context, exercise vigilance with respect to the interlocks, alarms, warning indicators and signs. A certified industrial radiographer shall:
Due consideration shall be given to female industrial radiographers of reproductive capacity. Female industrial radiographers, whether certified or in training, who are confirmed or declared pregnant shall discuss with the facility RSO their potential occupational doses and radiation hazards for the remainder of the pregnancy. (Should private or sensitive information about the radiographer's pregnancy be divulged in the discussion, such information shall be treated in a confidential manner.) Having been made knowledgeable of the potential occupational doses and radiation hazards associated with the work, should the pregnant industrial radiographer choose to continue radiography work, personnel monitoring shall be implemented on a monthly basis and the badge readings shall be promptly reviewed by the facility RSO to ensure that the pregnancy dose limit (in Appendix II, Table 1 of this Safety Code) is not exceeded. Records of these actions shall be properly documented and retained by the facility RSO. No pregnant industrial radiographer shall be re-assigned to other duties simply on the basis of information that the individual is pregnant.
Manufacturers of industrial x-ray equipment shall acknowledge that such equipment is federally regulated in Canada (refer to Section 3.1 of this Safety Code). It is the manufacturers' responsibility to ensure that their products comply with the RED ActFootnote 9 before they are imported, leased or sold in Canada. To facilitate demonstration of product compliance, manufacturers of industrial x-ray equipment or their marketing agents shall:
The regulatory authority may evaluate the product and provide a response to the manufacturer accordingly. (Evaluation and responses may take place 4-6 weeks following receipt of all required documentation and supportive evidence from the manufacturer.) The importation, lease or sale of industrial x-ray equipment that does not conform with the REDAct is unlawful. Any violation of the REDAct is a criminal offence.
In a case for which noncompliance is revealed after procurement or installation of the industrial x-ray equipment, the equipment manufacturer and the importer, upon written or verbal notification of the noncompliance by the regulatory authority or by the equipment owner, shall take the necessary actions to bring the equipment into compliance within 30 days from the date of noncompliance notifica tion. In such situations, the equipment owner is further advised to cease using the equipment until the noncompliance issues are resolved to the satisfaction of the regulatory authority. The manufacturer is solely responsible for providing training on the servicing, safety and radiation protection specific to the industrial x-ray equipment, and for issuing appropriately written authorizations to individuals so trained to carry out servicing.
Personnel responsible for servicing industrial x-ray equipment in a facility or other workplace shall:
Before any radiography services are undertaken at a client's facility, the client shall be briefed on the industrial radiography, the potential risks and hazards that are intrinsic to the work, the safety procedures that will be followed for the client's specific work required, applicable regulations, and proof of radiography personnel certification and training. This briefing shall be done by the certified industrial radiographer hired or authorized to perform the radiographic services at the client's premises, before any such services are carried out.
The client shall acknowledge that contractual conditions must not hinder the operating organization or individuals from performing the radiographic work safely, that is, regulatory and safety requirements take precedence in industrial radiography. The client must ensure that industrial radiography is conducted in a safe manner to minimize the risk of ionizing radiation exposure to the operators and others on site. The client shall, therefore, designate a safety officer to ensure that all safety procedures are being adhered to at the facility. Where different industrial radiography jobs on site are required, the issuance of work permits in conjunction with client supervision is necessary to reduce the likelihood of radiation accidents or abnormal exposures. Based on the foregoing, the client in conjunction with the radiography service provider shall prepare and retain a document (e.g., a checklist) which incorporates appropriate signatures and dates in order to demonstrate that the client was briefed on the safety issues relevant to the job, and is satisfied that appropriate safety actions were taken at the work site. Acopy of all documents so prepared shall be kept on file at the radiographer's facility and at the client's premises where the radiography was carried out.
Unauthorized individuals, other workers and staff in an organization or facility, and members of the general public, who might be in areas where industrial radiography is being carried out must adhere to all safety warnings, instructions and notices posted in such areas, and apply "common sense thinking and action"
for their own protection and safety. An individual who violates this 'standard of care' and incurs harm is deemed to have acted voluntarily in a negligent manner.
This part of the Safety Code outlines the regulatory requirements for industrial x-ray equipment, respecting design, compliance evaluation and enforcement; registration; and work site practice of industrial radiography.
X-ray equipment is federally regulated in Canada under the Radiation Emitting Devices (RED) ActFootnote 9 and companion regulations. The RED Act provides the authority to write regulations for specific classes of x-ray equipment. Where specific RED Act regulations are not available for a class of x-ray equipment, the general provisions of the RED Act respecting prohibition, deception and notification apply within the scope of ensuring worker and public safety. This is the case for industrial x-ray equipment. Thus, the importation, lease or sale of industrial x-ray equipment that does not conform with the RED Act is contrary to Canadian law. It is the manufacturer's and the importer's responsibility to ensure that the x-ray equipment available for commerce in Canada complies with the RED Act. Any violation of the RED Act is a criminal offence.
Re-sale industrial x-ray equipment shall also comply with the RED Act at time of sale. The seller is responsible for ensuring regulatory compliance of the equipment, for bearing the associated costs of compliance, and for notifying the buyer of his or her safety obligations upon acquisition of the equipment. Additional information is provided in Section 4.7 of this Safety Code.
Industrial x-ray equipment that is designed and constructed to conform with the following minimum requirements would meet the general provisions of the RED Act:
"ON/OFF"control from a location external to a controlled area that is established for temporary sites in accordance with Section 3.3.2. of this Safety Code;
All texts respecting radiation warning signs and labels required in this part shall be in black on a yellow background and be written in both English and French.
Any activity that might involve an assembled or ready-to-use industrial x-ray equipment carries an element of radiation risk. To ensure that the associated risks remain low, a system of control necessitating industrial x-ray equipment evaluation and operational review must be in place. This requirement exists in the Canada Labour Code Part II, Occupational Safety and Health Regulations, Part X, Section 10.26Footnote 5: essentially, all federal departments and agencies under federal jurisdiction must register their x-ray equipment with the regulatory authority, Health Canada. The registration process involves:
Where a confirmation of registration has been granted to a federal facility in accordance with Section 3.2.(iii) of this Safety Code and the facility subsequently makes a material change to the industrial radiography operation, safety procedures, permanent installation or to the industrial x-ray equipment, a supplementary report that clearly describes the change shall be submitted to the regulatory authority, Health Canada, for review within 14 calendar days of the said change. In this context, industrial x-ray equipment that has been re-sold, removed from service or transferred to other users or to another facility shall be reported. Failure to file such a supplementary report would automatically invalidate the confirmation of registration.
Re-registration shall occur every three years, unless specified otherwise. Afacility that operates industrial x-ray equipment without a valid confirmation of registration would be in contravention of the federal Occupational Safety and Health RegulationsFootnote 5.
Radiography may be carried out in a permanent installation site and/or at a temporary job site. These sites are characterized by differences in work conditions and therefore hazard reduction strategies must integrate both the industrial x-ray equipment and human factors.
In the majority of cases industrial radiography is carried out in a shielded enclosure. When a shielded enclosure is properly designed and constructed using sound engineering principles and operated within the design limitations, no 'Controlled Area' external to it is created. However, if conditions do not merit a controlled area, the occupational exposure conditions need to be kept under review by the RSO. This scenario would constitute a 'Supervised Area' for which the following actions are required:
The planning of a permanent installation should follow life-cycle management concepts. Though not exhaustive, a number of factors need to be considered: siting, location, construction, commissioning, operation, maintenance and decommissioning based on present and foreseeable future needs. Drawings of the enclosure and its surroundings should be prepared; entrances should be identified; and dimensions and personnel occupancy areas need to be specified as well. Heating, lighting, ventilation and utility requirements also merit attention. Shielding, interlocks, warning indicators, emergency activators, and radiation control systems and stations require in-depth consideration because of their importance to radiation safety. Generally, limitation of external radiation exposure to personnel, due to the use of ionizing radiation sources present inside the installation, requires shielding. Estimates of shielding thickness may be determined using established methodsFootnote 15; users of this reference should ensure appropriate dose limits are used when determining shielding estimates. Often, depending on the nature of the work or location of the installation, penetration of the shielding will be necessary for various reasons, such as, to place or remove heavy test objects in the primary beam using overhead cranes, robots or conveyor; to provide in the enclosure access for personnel entry and exit; to facilitate passage of utility pipes and x-ray control or imaging cables; to affix lights; and to provide essential heating and ventilation duct systems. Inadequate shielding at such discontinuities might lead to unacceptable levels of stray radiation, which potentially could expose personnel or the public, thereby increasing radiation risks. Guidance for effective shielding at such discontinuities is availableFootnote 15. Though infrequent, operational demands may involve the replacement of an existing radiation source with one of a higher beam penetration capability (that is, higher energy x rays), and this may require changes to the installation shielding or re-consideration of primary and secondary barriers or to occupancy of surrounding areas. Based on the foregoing, it is essential that a radiation protection adviser be consulted (or hired) to advise on matters relevant to radiation safety. The expert may be a consultant who is competent in the field of ionizing radiation protection and safety and has several years experience in the design of ionizing radiation shielded facilities. However, responsibility for compliance with the relevant regulations and standards remains with the organization or agency having ownership of the permanent installation. The minimum requirements for a permanent installation are:
| State or condition | Colour |
|---|---|
| Radiation ON | Red |
| Emergency | Red |
| Warning (stand-by) | Amber or yellow |
| Radiation OFF (safe) | Green |
| Information | Blue |
All texts respecting radiation warning signs and labels required in this part shall be in black on a yellow background and be written in both English and French. Before a newly constructed or modified permanent installation is commissioned for use, an on-site evaluation must be conducted.
The use of engineering controls at temporary job sites is limited. Consequently, strict adherence to administrative measures is necessary to reduce the likelihood of radiation accidents and unintentional exposures. Individuals must therefore receive training and instructions commensurate with the work procedures, and they must be committed to safety. To the extent practical, radiography should be performed at times when personnel occupancy of the ambient area is lowor zero. Use should be made of collimators and secondary shielding (walls, shielded enclosures, vehicles unoccupied by humans, mobile lead screens), where practical, to reduce dose levels.
The minimum requirements for radiography at a temporary job site are:
| State or condition | Colour |
|---|---|
| Radiation ON | Red |
| Emergency | Red |
| Warning (stand-by) | Amber or yellow |
| Radiation OFF (safe) | Green |
| Information | Blue |
All texts respecting radiation warning signs and labels required in this part shall be in black on a yellow background and be written in both English and French.
On-site evaluation is intended to ensure compliance with the requirements of this Safety Code. It must be conducted by the regulatory authority; equivalents may be permitted provided that prior consent has been obtained from the regulatory authority. Such an evaluation should confirm that
On-site evaluations may be conducted periodically or at any time.
This section provides information for guidance purposes.
Accelerators used for industrial radiography produce photons in the MeV range at high dose rates. For example, a 3 MV-Linatron accelerator can produce a dose rate of 3 Gy per minute at 1 metre and a similar device operating at 9 MV can yield a dose rate of 30 Gy per minute at the same distanceFootnote 16.
High-energy (MeV) photons can interact with atomic nuclei, causing nuclei transformation and release of energy in the form of photons or energetic particles or a combination of both. One such particle can be a neutron. The interaction process is called photodisintegration. This reaction is energetically feasible whenever the photon energy exceeds the binding energy of a proton or neutron in the atom nucleus. For materials heavier than hydrogen, except beryllium, the photon threshold energy for such reactions is generally >5 MeVFootnote 17. For accelerators operating at <6 MV, the neutron yield from photodisintegration reactions would be extremely low and therefore would not be a concern as a radiation hazardFootnote 18.
This procedure normally employs radioactive-based sources. The procedure, practice or radiation source is beyond the scope of this Safety Code.
Industrial x-ray equipment may occasionally be used for purposes other than industrial radiography. In a facility in which this is the case, it is the responsibility of the industrial x-ray machine owner in that facility to (a) ensure that individuals using the x-ray equipment for non-radiography purposes have the appropriate education, training and competence; and (b) determine the individuals' suitability for the particular job intended.
Radiation safety education should be consistent with that of a Radiation Safety Course, such as the one administered by the NDE Institute of CanadaFootnote 19 or equivalent. The training and education should include:
The RSO shall identify the subset of industrial x-ray equipment users who are engaged in non-radiography work, and ensure that they have the necessary education and training and have demonstrated competence before undertaking the job in question. Except for the certification criterion, the requirements of Section 2.3 of this Safety Code shall apply to that subset of industrial x-ray machine users.
Personnel monitoring devices are needed to record and control whole-body exposures to ensure occupational limits are not exceeded in accordance with the ICRP recommendations (Appendix II of this Safety Code). For external dose monitoring purposes, devices should be worn on the clothing closest to the body either at the waist or chest level. Patented and state-of-the-art personnel monitoring systems, capable of registering and reporting dose levels as low as 0.01 mSv, are readily availableFootnote 12 ; older technology also existsFootnote 13. As a general guide to users of ionizing radiation sources, it is extremely important to notify your dosimetry service provider of the radiation sources you are using or likely to use, seek the appropriate passive dosimeters, and ensure that your occupational doses reported, correctly reflect the contribution from the various radiation sources you are using.
Industrial radiographers and other users must wear photon-sensitive passive dosimeters as well as instantaneous reading electronic alarm dosimeters. Each passive personal dosimeter must be worn by only one individual. It is advised that passive detectors be stored in a secure, properly shielded location between periods of use to avoid registering exposures from extraneous sources. Personnel monitoring data need to be retained as a permanent record and be made readily available for review by industrial radiography personnel, other users of the equipment and the regulatory authority.
Computation of occupational doses for purposes of assessment against worker dose limits recommended by the ICRP (refer to Appendix II in this Safety Code) must be based on the summation of all exposures incurred by the individual from the ionizing radiation sources used in industrial radiography. Photon-sensitive passive detectors collectively record x-ray and gamma-ray components. Natural background radiation or medical radiation contributions are not computed as occupational exposures.
An electronic personnel dosimeter not only provides direct dose reading capability, but also is designed to emit an audible signal intended to provide instantaneous feedback to its wearer about the radiation conditions prevailing in an area. The alarm set point may be for a dose rate or an integrated dose. Electronic alarm dosimeters shall (i) be checked to ensure proper functioning before use; (ii) be set to give an alarm at a preset dose equivalent rate of 5 mSv/h or an integrated dose of 2 mSvFootnote 14, with an accuracy of ± 20 %of the true radiation dose; (iii) be calibrated at periods not exceeding 12 months; and (iv) require special means to change the preset alarm function. Following activation of the alarm, the dosimeter wearer is obligated to exercise appropriate radiation control measures to reduce his or her occupational dose. Such dosimeters work reasonably well for conventional x-ray (and gamma-ray) sources. However, there are radiation sources that produce very high x-ray levels in a time frame in the order of microseconds (e.g., flash x-ray sourcesFootnote 20) and the electronic personnel dosimeter may not have sufficient time to respond within that time frame; this sub-optimal dosimeter response could be falsely interpreted to mean the absence of x rays. Thus, an alternative dosimeter that provides direct dose reading display capability should be used, provided that it has been tested to provide reliable results and the wearer must be aware of any inherent limitations thereof. Direct dose-reading dosimeter results shall be recorded for individual wearers.
To avoid underestimation of the exposure rate from industrial x-ray equipment, the cross-sectional area of the radiation beam must be larger than the sensitive area of the survey meter detector. For routine survey work the meter should yield readings that are accurate to ± 20%.The energy response should be flat to within ± 20% over the desired photon energy range to be encountered. Survey meters that utilize an ionization chamber must be calibrated over the energy range for which they are to be used; calibration factors shall be used to convert the meter readings to appropriate dose values. A meter having several measurement ranges provides greater flexibility. A meter that provides maximum scale readings in the range of 10 µSv/h to 10 mSv/h (or the equivalent in exposure or dose units) is suggested. The detector response time must be short enough for an accurate radiation measurement. The meter must not exhibit "fold-back"
under any circumstances. Fold-back is said to occur when an instrument is exposed to an exposure (or dose) rate or cumulative exposure (or absorbed dose) in excess of its display range and shows a lower or zero reading. Ideally, a meter that is designed against fold-back should show an off-scale deflection or, in the case of a digital display, show an overload condition when it is exposed to ionizing radiation fields that exceed the measurement range. In work areas where radio frequency (RF) fields might be present ensure that the survey meter is not sensitive to the ambient RF fields (by wrapping the meter in metallic gauze).
Several web sites may be consulted regarding radiation protection instrumentationFootnote 21.
Unintentional exposure to radiation may be caused by equipment failure or human error or a combination of both. Radiation accident victims must receive prompt medical attention by a physician. In addition, the root cause of the incident must be investigated and remedial measures taken to prevent recurrence at the facility. To address such situations, the facility is responsible for developing an emergency response plan and having the capabilities to implement the plan. Personnel must be trained to handle emergency equipment and to follow written procedures. The plan shall be tested and validated, and deficiencies shall be identified and corrected. The facility needs to liaise with the various personnel identified in the emergency procedures.
As a guide, the generic emergency response plan should include:
The facility shall prepare a written report that contains: a description of the accident; methods used to protect other workers and the public; assessments of exposures to the accident victims, workers, emergency services personnel and members of the public; cause of the accident and corrective actions. That report shall be submitted (by the RSO) to the regulatory authority for review and follow up within 5 calendar days after the incident (see Section 2.2.1.23. of this Safety Code).
X-ray equipment intended for resale shall also comply with the RED Act and regulations at time of sale. The seller is responsible for
If the purchaser's facility is under federal jurisdiction, the Nonmedical X-Ray Unit, Consumer and Clinical Radiation Protection Bureau, Health Canada shall be contacted and the facility shall adopt this Safety Code. Otherwise, the appropriate provincial or territorial radiation protection authority shall be contacted to determine the applicable operational requirements for the x-ray machine.
For the disposal of an x-ray machine, the RSO shall observe the instructions provided by the manufacturer in the product manual or contact the manufacturer for information and guidance. In a case where a manufacturer is no longer in the business of manufacturing, selling or servicing industrial x-ray equipment, the following procedures shall be followed:
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http://www.tbs-sct.gc.ca/pubs_pol/hrpubs/TBM_119/haz_e.asp
Accessed 19 April 2002.
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http://laws.justice.gc.ca/en/L-2/sor-86-304/text.html
Accessed 26 February 2002.
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http://www.hc-sc.gc.ca/hecs-sesc/rpb/fptrpc_members.htm
Accessed 23 April 2002.
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http://www.hps.org/p ublicinformation/ate/q143.html
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http://www.canlii.org/ca/regu/cr c1370 Accessed 10 March 2003.
Canada General Standards Board. Non-Destructive Testing - Qualification and Certification of Personnel (ISO 9712: 1999,MOD). Ottawa: Canada General Standards Board; National Standards of Canada, CAN/CGSB - 48.9712-2000; 2000.
Canada General Standards Board. Certificate of Nondestructive Testing Personnel (Police and Security Radiography Method). Ottawa: Canada General Standards Board; National Standards of Canada, CAN/CGSB - 48.20-94; 1994.
Website on radiation dosimetry services.
http://www.landauerinc.com
Accessed 15 April 2002.
Websites that provide information on radiation dosimetry services.
http://www.dosimetry.com; http://www.hc-sc.gc.ca
Accessed 15 April 2002.
Canadian Nuclear Safety Commission.
Nuclear Substances and Radiation Devices Regulations. Ottawa; Nuclear Safety and Control Act. SOR/2000-207. 2000. Available at:
http://la ws.justice.gc.ca/en/N-28.3/SOR-2000-207/index.html
Accessed 02 July 2001.
National Council on Radiation Protection and Measurements. Structural Shielding Design and Evaluation for Medical Use of X rays and Gamma rays of Energies Up to 10 MeV. Bethesda. MD; NCRP, Report 49, 1976.
Varian Medical Systems.
Industrial Products: Field Portable X-ray Systems. 2001. Available at :
http://www.varian.com/ind/lnm000a.html
Accessed 26 July 2001.
Choppin, G.R., Rydberg, J. Nuclear Chemistry. Pergamon Press:
Toronto;1980.
National Council on Radiation Protection and Measurements. Neutron Contamination from Medical Accelerators. Bethesda. MD; NCRP, Report 79, 1984.
Web site that provides information on radiation safety course.
Available at:
http://www.ndeinst.org/co urses/rad_safety.shtml
Accessed 17 December 2002.
Physics International Company. Selection Guide for Flash X-ray
Systems. San Leandro, California. Technical Bulletin 5952-6701, 1995. Available from: Olin Corporation Aerospace Division, 2700 Merced St., San Leandro, Ca 94577-0599, USA.
Websites that provide information on Radiation Protection Instrumentation.
http://www.inovision.com
http://www.eberline.com
http://www.ludlums.com
http://www.thermo.com/rpm
http://www.cardinal.com Accessed 27 February 2002.
The following definitions apply to this Safety Code.
The X-ray warning sign referred to in this Safety Code is a sign that:
"CAUTION, X-RAYS : NO UNAUTHORIZED USE"and
"ATTENTION, RAYONS X: UTILISATION NON AUTORISEE"; and

c. bears the words "CAUTION, X-RAYS: NO UNAUTHORIZED USE"
and « ATTENTION, RAYONS X : AUCUNE UTILISATION NON AUTORISÉE »
; and
In its 1990 Publication 60Footnote 1, the International Commission on Radiological Protection (ICRP) recommended dose limits for ionizing radiation. The dose limits do not include medical and natural background ionizing radiation exposures and are indicated below.
| Person | Period | Effective Dose (mSv) |
|---|---|---|
| Radiation worker | (a) One year | (a) 20 (average) 50 (special circumstances) |
| (b) 5- year period | (b) 100 | |
| Pregnant radiation worker |
Remainder of pregnancy | 2 |
| Public | One year | 1 |
|
||
| Tissue or Organ | Person | Period | Equivalent dose (mSv) |
|---|---|---|---|
| Skin | (a) Radiation worker | One year | 500 |
| (b) Public | One year | 50 | |
| Lens of the eye |
(a) Radiation worker | One year | 150 |
| (b) Public | One year | 15 | |
| Hands and feet | (a) Radiation worker | One year | 500 |
| (b) Public | One year | 50 |
| Organ or Tissue | Weighting Factor, wT |
|---|---|
| Gonads (testes or ovaries) | 0.2 |
| Red bone marrow | 0.12 |
| Colon | 0.12 |
| Lung | 0.12 |
| Stomach | 0.12 |
| Bladder | 0.05 |
| Breast | 0.05 |
| Liver | 0.05 |
| Oesophagus | 0.05 |
| Thyroid | 0.05 |
| Skin | 0.01 |
| Bone surface | 0.01 |
| Remainder organs mean all organs and tissues, excluding the twelve
listed above, and include: adrenals, brain, upper large intestine, small
intestine, kidney, muscle, pancreas, spleen, thymus and uterus |
0.05 |
| Whole body | 1 |
|
|
| Radiation type and energy | Radiation weighting factor, wR |
|---|---|
| Photons, all energies | 1 |
| Electrons and muons, all energies |
1 |
| Neutrons of energy < 10 keV | 5 |
| Neutrons of energy 10 keV to 100 keV | 10 |
| Neutrons of energy >100 keV to 2 MeV | 20 |
| Neutrons of energy > 2 MeV to 20 MeV | 10 |
| Neutrons of energy > 20 MeV | 5 |
| Protons, other than recoil protons, of energy > 2 MeV | 5 |
| Alpha particles, fission fragments, heavy nuclei | 20 |
|
|
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Device registration applies to facilities under federal jurisdiction, pursuant to Canada Labour Code Part II, Occupational Health and Safety Regulations, Part X, Section 10.26. There are forms and attachments that need to be submitted to facilitate device registration.The completed registration form and all supporting materials shall be sent to:
Health Canada,
Consumer and Clinical Radiation Protection Bureau,
NonMedical X-rays,
A.L. 6301A,
775 Brookfield Road,
Ottawa, Ontario K1A 1C1.
Industrial X-Ray Machine Registration
This attachment contains 2 pages. The owner is required to submit specific information in order to register the industrial x-ray device.
Emergency Procedures For Unintentional Exposure to X-Rays
The emergency procedures required are specific to the case where a worker is unintentionally exposed to radiation generated by the x-ray machine. The facility shall have in place a policy to follow such written procedures that: reflect prompt medical treatment for the exposed or allegedly exposed victims; specify the designated medical institution; include directives for the disclosure of radiation exposure information to the attendant medical staff at the medical institution and for the requisition of consultation by a radiation oncologist. Contact information on personnel provided in the emergency procedures shall remain current.
Accident Investigation Report
This form shall be used to promptly notify Health Canada and other relevant parties about any radiation accident. Following the complete investigation all sections are to be completed in full. A completed report shall be submitted to Health Canada at the address provided above within 5 calendar days of the accident.
Attachment A - Industrial X-Ray Machine Registration
(Pursuant to Canada Labour Code Part II "Occupational Safety and Health Regulations"Footnote a)
Any changes to items (B), (C), (D), or (E) will require a re-registration within 10 calendar days.
http://www.hc-sc.gc.ca/hecs-sesc/ccrpb/publication/safety_code34/index.html
OFFICE USE ONLY
Nonmedical Industrial x-ray equipment, Health Canada Registration Form Dec. 2003
Attachment B - Emergency Procedures For Unintentional Exposure to X-Rays
Accidental exposure: Accidental exposure is considered to be unintentional x-ray exposure to any part of the human body. This c an o ccur if safety and operational procedures are not followed or if the equipment is not properly installed or serviced.
Measures to be taken in the event of accidental or suspected exposure to x-rays:
Note:
The user should complete the blanks in the preceding emergency procedures specific to the facility, hospital / health care facility, and contracted maintenance provider. It is the responsibility of the equipment owner to ensure that all operators and operators' Supervisor adhere to these emergency procedures, and that the contact information on personnel presented in the emergency procedures remains current.
Attachment C - Accident Investigation Report