Temperature increase estimates for transabdominal obstetrical exposures

The purpose of the contribution is to estimate the temperature increase for transabdominal obstetrical exposures. The monopole-source solution was used to calculate the 3D complex acoustic pressure field for focused circular apertures from which the 3D temperature distribution was calculated using the bio-heat transfer equation in a layered, perfused media. For the 114 cases, the acoustic field was normalized to the transmit acoustic power required for the derated spatial peak, temporal average intensity I_SPTA.3 equal to 720 mW/cm² for the applicable homogeneous tissue model, the maximum value allowed by the FDA 510(k) diagnostic ultrasound equipment approval process. For the I_SPTA.3=720 mW/cm² condition, the axial temperature increase profiles and maximum temperature increases were determined within the anterior abdominal wall and conceptus. Also, from the normalized acoustic field, the soft-tissue thermal index TIS was determined according to the procedures of the output display standard. The results suggest that the TIS is an adequate indicator for monitoring the myometrium´s, and possibly the fetus´, maximum temperature increase