Final answer:
The College of Medical Radiation Technologists of Ontario (CMRTO) sets the standards of practice for all Medical Radiation Technologists in Ontario.
Step-by-step explanation:
The group that established the standards of practice for MRTs (Medical Radiation Technologists) in Ontario is the College of Medical Radiation Technologists of Ontario (CMRTO). The CMRTO is a regulatory body that sets the standards of practice for the medical radiation technology profession to ensure the public receives safe and effective care. They are responsible not just for a select few, but for all registered MRTs practicing in Ontario, regardless of the area of specialization within the field, which includes radiography, radiation therapy, nuclear medicine, and magnetic resonance imaging.