Computation of temperature elevation in fetus due to radio-frequency exposure with a new thermal modeling

The temperature elevation in the fetus is of concern for radio-frequency exposure. According to the IEC standard, the temperature elevation in the fetus should be lower than 0.5°C for exposure in magnetic resonance equipment. However, no previous study succeeded to simulate the temperature difference between the fetus and mother in the thermoneutral condition. The present study proposes a new thermal modeling for the pregnant woman model. The thermal modeling is then applied to the temperature variation for plane wave exposure at 80 MHz. From computational results, the core temperature in the fetus at the themoneutral condition was 37.5°C, which is 0.35°C larger than that of the mother and coincident with measured data. When the pregnant woman model is irradiated by the plane wave with the whole-body averaged specific absorption rate of 2 W/kg for 1 hour, the temperature elevation in the fetus is 0.50°C, which is larger than that in the mother by 0.11°C.