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Veterinary Dental X-Ray Machine Installation

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.

Dental X-ray machines provide a valuable adjunct to modern veterinary care. In Ontario, the installation and use of these X-ray sources is regulated, in part, by Ontario Regulation 861 under the Occupational Health and Safety Act. This Regulation sets out requirements relating to health and safety of workers exposed to X-ray. For example, before the installation or use of anX-ray machine, the employer must register his/her workplace and X-ray sources with the Ministry of Labour's Radiation Protection Service, and have the appropriate forms, application for review, and plan location drawings reviewed and accepted by the Ministry.

In addition to general requirements in Regulation 861, section 16 has specific requirements relating to X-ray machines used for the diagnostic examination of animals. For example, where practicable, the dental X-ray machine should be installed or used in a room designed for the purpose of performing X-ray examinations of animals. In addition to the applicable general requirements of Regulation 861 and the specific requirements in section 16, where it is not practicable to have a dedicated X-ray room, a dental X-ray machine may be installed and used in a general animal treatment room, only if the room meets all of the following conditions:

  1. The dental X-ray machine must be permanently installed in the general treatment room with the exposure switch located in an area shielded from X-rays. The operator should stand outside the room (now used as a dental X-ray room) using the room walls as the protective shield. The labeled exposure switch can be mounted on a wall outside the dental X-ray room (similar to a light switch) or the switch can be on a cord long enough to permit the operator to remain in a shielded location (e.g., to leave the room). Hand-held, portable or stand-mounted dental units are not permitted in veterinary facilities.
  2. All workers, including the veterinarian, must leave the dental X-ray room during exposures. Animals should be chemically and/or physically restrained or supported by mechanical means during exposures. If it is absolutely necessary for someone to remain in the room to support or restrain an animal during an exposure, he or she must be provided with personal radiation protective equipment and dosimetry.
  3. All access to the dental X-ray room must be controlled during the dental X-ray exposure by either door interlocks [ 1 ] or visual control. The exception would be an operator standing at the doorway, "guarding" that access point.
  4. The dental X-ray floor plan review, including the associated Form 2, must be designed to ensure that the X-ray beam is pointed only at barriers designed and approved for primary (main) beam exposure. Unlike larger veterinary radiographic X-ray machines, a dental X-ray machine can be pointed at room barriers other than the floor. The acceptable manner of directing the X-ray beam would be documented in written procedures.
  5. Written policy and procedures must be developed, posted in the workplace, and all facility staff shall be instructed in dental X-ray safety procedures as they apply to their job function.


"Smile! You Have Decided to Install a Dental X-ray Machine" by Angela Cerovic. Focus magazine, July/August 2007, page 17. Ontario Veterinary Medical Association.

For additional information and forms, and to have your forms and plans reviewed contact:

Radiation Protection Officer
c/o Radiation Protection Service
Ontario Ministry of Labour
81A Resources Road
Toronto, Ontario
M9P 3T1
(416) 235-5922 or

[ 1 ] An interlock is an electrical switch. If a door is open or is opened during an X-ray exposure, the X-ray exposure will not start or, if started, would be terminated and will not restart if the door is closed. Typically, interlocks are connected in series with the exposure switch to interrupt the electrical power to the dental X-ray unit. A kitchen microwave oven door is an example of what is required; the oven will not start with the door open, and if the door is opened while the oven is operating, the oven will shut off.

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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.