Disclaimer: This resource has been prepared to help the workplace parties understand some of their obligations under the Occupational Health and Safety Act (OHSA) and regulations. It is not legal advice. It is not intended to replace the OHSA or the regulations. For further information please see full disclaimer.
Radiation protection comprises a hierarchy of control measures. Engineered design and construction, administrative policy/procedures and personal protective equipment address the three fundamental principles of dose reduction: time, distance and shielding. In open beam x-ray applications where an x-ray worker must remain in the x-ray room, personal protective equipment (PPE) is the last layer of defence in reducing exposure to ionizing radiation after optimizing all other engineering and administrative controls.
Under the Ontario Occupational Health and Safety Act (OHSA), the employer, supervisor and worker have duties with regard to protective equipment (or devices). They include:
The intent of PPE is to ensure that the dose equivalent received by a worker is as low as reasonably achievable and that the limits in the Regulation respecting X-Ray Safety (Reg. 861) are not exceeded.
The Regulation respecting X-ray Safety (Reg. 861) made under the OHSA requires protective aprons and gloves, providing shielding equivalent to at least 0.5 mm of lead to be available for persons providing restraint or support to an animal in veterinary x-ray applications.
Workplaces covered by the Health Care and Residential Facilities Regulation (O. Reg. 67/93) are required to develop, establish and put into place written measures and procedures which may deal with but are not limited to: safe work practices, the proper use, maintenance and operation of equipment; and the use and wearing and care of PPE and its limitations, in consultation with the joint health and safety committee (JHSC) or health and safety representative (HSR) (if any). Employers are required to review and revise these measures and procedures at least once a year in light of current knowledge and practice. The employer is also required, in consultation with the JHSC or HSR (if any), to develop, establish and provide worker training and educational programs on relevant OHS measures and procedures.
In settings where workers are required either by O. Reg. 67/93 or their employer to use PPE:
Section 15 of O. Reg. 67/93 requires that a worker who supports, positions or restrains a patient or resident in a health care facility during an x-ray examination be provided with, and wear, a protective apron, gloves and collar (where applicable) having a lead equivalence of at least 0.5 mm.
Workplaces covered by the Regulation for Industrial Establishments (Regulation 851) that require PPE to protect workers from exposure to x-rays must comply with section 79 of Regulation 851 which states:
The OHSA also contains a variety of general duties including the duty on employers to take every precaution reasonable in the circumstances for the protection of a worker.
As a general matter, what follows are examples of what may be considered to be reasonable precautions in the context of PPE in radiology.
A comprehensive PPE program is important. The employer, designated competent person, supervisor or radiation protection officer (as per Regulation 543) should assess each worker’s need for protection according to the work he or she is required to perform in the required environment. The PPE program should include the following elements:
The shielding achieved by the PPE at a specific x-ray energy (expressed as kVp) should be as great as, or greater than, the shielding which would be achieved by a 0.5 mm thickness of non-alloyed lead at that same specific energy. This equivalency of shielding should be over the range of energies used in a particular room or application.
The effectiveness of lead aprons and thyroid collars in reducing exposure to leakage or scatter radiation relates directly to their physical construction, fit, and how they are used.
Any toxic material used for the attenuation of x-rays in PPE should be sandwiched between inert material or encapsulated in a substance which does not allow the toxic material to come in contact with the wearer. The attenuating material should be affixed to the encapsulating material to prevent the material from sagging, delaminating, tearing or distorting over time.
The fit of the protective equipment should be such that all of the organs and parts of the body which are intended to be protected are protected in all postures and attitudes (relative orientation to the x-ray source or scattering object) assumed by the worker during an x-ray procedure. This may involve custom fitting; but at the very least, the worker should have a choice of sizes.
The fit of wrap-around aprons should be such that the overlapping material provides appropriate and adequate shielding. The area of the body covered by this material should include the entire front of the body (anterior surface) and should extend to the posterior midline of the body.
The thyroid collar and apron should fit together in a complementary fashion so that there are no gaps between them.
If a worker’s duties necessitate turning his or her back to the scattering object (patient) for a significant portion of time (based on the risk assessment), the lateral and posterior layers of the protective equipment should provide appropriate and adequate shielding. In dose-intensive applications such as angiography, heart catheterization and interventional imaging, open-backed aprons are not acceptable for use by anyone other than the fluoroscopist controlling the foot pedal or exposure switch.
Ergonomic issues should be considered when purchasing an apron. Lumbar support in the form of weight belts and padded shoulders can improve the product comfort, and reduce the risk of back injury. Separate skirts and tops can redistribute weight so as to bear on several large body joints. Manufacturer’s instructions should be followed regarding maintenance and storage. For example, aprons should be hung up when not in use. They should never be folded, wrinkled or creased.
In procedures where scatter radiation to the lens of the eye could approach the annual dose equivalent limit of 150 millisieverts, as per Regulation 861, the use of leaded glasses is recommended.
Protective gloves or gauntlets must possess at least 0.5 mm lead equivalency throughout the glove, including fingers and wrist, as per O. Reg. 67/93.
PPE should be labeled with the lead-equivalent thickness of the material permanently and legibly marked as per Health Canada Safety Code 35. The specific room the apron is used in, or application the apron is used with, should also be specified on the label.
Documentation that particular protective equipment provides appropriate and adequate shielding can be obtained from the vendor or manufacturer in the form of a certificate or by physical comparison testing. Verification testing could involve comparing the grey scale, optical density or radiation measurements between the protective equipment and a 0.5 mm thickness of non-alloyed lead over the range of energies (kVp) used in a particular room or application.
It is generally an acceptable quality assurance practice to verify the integrity of the PPE every six months. This can often be done by a documented visual and tactile inspection. In addition, a documented fluoroscopic examination or written assessment of radiographic film(s) should be conducted at least annually or more frequently if use, conditions or other circumstances require. Records of testing, and follow-up documentation should be available on demand to Ministry of Labour inspectors. This is a general duty of an employer under clauses 25 (1) (a) and (b) of the OHSA.
Any protective equipment that exhibits visual, tactile or x-ray examination defects, must be repaired or replaced. This includes tears, separation from stitching, distortion producing a non-uniform attenuation and multiple pinholes or punctures.
In summary, lead apparel which contains defects such as holes or cracks should be decommissioned if the aggregate area of the holes or cracks exceeds those in the table below:
Type of apparel | Total or aggregate area |
---|---|
Lead apron with built-in thyroid shield | 10 cm2 whole-body 0.2 cm2 or 20 mm2 reproductive region 1 cm2 neck region |
Separate thyroid shield | 0.03 cm2 or 3 mm2 |
Gauntlet | 3 cm2 |
[1]Reference: Emerenciana Duran and Brian Phillips, Rejection Criteria For Defects In Lead Apparel Used For Radiation Protection Of X-ray Workers (PDF). Radiation Protection Services, BC Centre for Disease Control, March 1, 2003
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Disclaimer: This web resource has been prepared to assist the workplace parties in understanding some of their obligations under the Occupational Health and Safety Act (OHSA) and the regulations. It is not intended to replace the OHSA or the regulations and reference should always be made to the official version of the legislation.
It is the responsibility of the workplace parties to ensure compliance with the legislation. This web resource does not constitute legal advice. If you require assistance with respect to the interpretation of the legislation and its potential application in specific circumstances, please contact your legal counsel.
While this web resource will also be available to Ministry of Labour inspectors, they will apply and enforce the OHSA and its regulations based on the facts as they may find them in the workplace. This web resource does not affect their enforcement discretion in any way.
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