Thermal Effects Associated with RF Exposures in Diagnostic MRI: Overview of Existing and Emerging Concepts of Protection

Figure 2

Typical distribution of predicted Specific Absorption (SA, in bins of 250 J/kg) observed in clinical use of 1.5T MRI examinations for all body parts at multiple hospitals. The blue curve (left axis) shows the percentage of examinations as function of exposure. Less than 10% of the examinations is performed with SA > 3 kJ/kg. Use of much higher SA values is, however, not uncommon, as shown by the orange curve (right axis, fraction of examinations in ppm): approx. 1 of patients are exposed to > 7 kJ/kg, and 0.1 to > 10 kJ/kg.