Regulations
Ontario Regulations

The Healing Arts Radiation Protection (HARP) Act governs medical use of x-rays.
The HARP Act contains some segments that govern worker x-ray safety, but Regulation 861 under the Occupational Health and Safety Act has primary governance over this. This regulation also governs the use of non-medical x-rays.
Canadian Regulations and Safety Codes

The Radiation Emitting Device (RED) Act sets standards for all new x-ray devices.
Health Canada provides a number of Safety Codes to govern use of various types of radiation. Safety Code 35 in a safety code for large healthcare facilities using x-ray. The Safety Codes are not binding in provinces with their own x-ray safety regulations, BUT Safety Code 35 gives radiation protection recommendations based on international standards so it should be considered words for the wise.