What is the specific absorption rate (SAR) limit for the whole body in first-level controlled operation mode?

The specific absorption rate (SAR) limit for the whole body in first-level controlled operation mode is set at 4 W/kg. This value is established to ensure safety during MRI procedures, reflecting the maximum level of radiofrequency energy that can be absorbed by body tissues without causing adverse health effects.

In the context of MRI safety, first-level controlled mode indicates that individuals may have a higher understanding of the risks associated with electromagnetic fields. The 4 W/kg limit is a guideline provided by safety standards to protect patients and personnel while still allowing for the effective use of MRI technology. Adhering to this limit helps minimize the risk of thermal injury or other potential effects from excess RF energy exposure.

The other values mentioned in the options either exceed the established safety limit or do not align with current regulatory standards for MR imaging. Therefore, 4 W/kg is recognized as the appropriate threshold for ensuring safe practice in first-level controlled environments.