What is the limit of SAR for whole body exposure?

• A. 3.2 w/kg
• B. 4 w/kg
• C. 8 w/kg
• D. 2 w/kg

Answer: (B)

The specific absorption rate (SAR) is a measure of the rate at which energy is absorbed by the body when exposed to a radiofrequency electromagnetic field, such as that produced during magnetic resonance imaging (MRI) procedures. For whole-body exposure, the limit set by regulatory agencies and safety guidelines is crucial to ensure patient safety during MRI scans.

The accepted limit for SAR for whole-body exposure is 4 watts per kilogram (w/kg). This limit is based on extensive research and is meant to prevent any potential health risks associated with high levels of radiofrequency energy exposure. This threshold is established to keep the thermal effects of RF energy within safe limits, thereby minimizing any risk of overheating tissues and other physiological effects.

Understanding SAR limits is essential for MRI technologists to ensure that the imaging procedures comply with safety standards, providing effective diagnostic imaging while safeguarding patient health.