Radiation dose to the fetus from [ ¹⁸F]-FDG administration during the second trimester of pregnancy

The authors estimated the fetal radiation dose from [ ¹⁸F]-FDG in a rare case of a woman who underwent a PET/CT scan during the second trimester of pregnancy. The patient, a 27-y-old female with a paraganglioma, received 181.3 MBq [ ¹⁸F]-FDG. From the concentrations of radioactivity measured on the images, the time-integrated activity coefficients of the fetus and the placenta were derived. The time-integrated activity coefficients of the mother's organs were taken from the standard values of ICRP publication 106. The final fetal dose was calculated using the 6-mo pregnant model of the OLINDA/EXM software. The fetus showed an overall low and homogeneous [ ¹⁸F]-FDG uptake, with an average concentration of 2.41 kBq cm ^-3. The uptake in the placenta was generally higher (average concentration = 3.69 kBq cm ^-3). The estimated time-integrated activity coefficients were 0.0130 and 0.0058 Bq h Bq ^-1 for the fetus and the placenta, respectively. The final average dose to the fetus was 1.97 × 10 ^-2 mGy MBq ^-1 (3.6 mGy in this patient who received 181.3 MBq). Therefore, the dose to the fetus from [ ¹⁸F]-FDG administration during the second trimester of pregnancy is low. When medically indicated, pregnancy should not be a categorical basis for withholding [ ¹⁸F]-FDG PET scans.