Fetus doses from radionuclide diagnostic of pregnant patients

The aim of the work was to estimate the radiation doses to the fetus during radionuclide diagnostic procedures in pregnant patients. Materials and Methods: The absorbed doses to the fetus due to the radiopharmaceutical administered to the mother during radionuclide diagnostic procedures were estimated for the most common procedures performed in the Russian Federation using the conversion factors from the administered activity of radionuclides in the radiopharmaceutical to the absorbed dose. Typical values of the administered activities of radionuclides for each radiopharmaceutical and the conversion factors taking into account the stage of pregnancy of the patient at which the study was conducted were used. For comparison, the absorbed doses to the mother's uterus, as the closest organ, were determined. For hybrid studies, the absorbed doses to the fetus from maternal CT scans at different stages of pregnancy were calculated in the FetalDose program for typical scanning protocols for adult patients. Results and Discussion: The absorbed doses to the fetus from the administered radiopharmaceutical for most studies do not exceed 20 mGy. In hybrid studies where the CT scan area includes the abdominal region, the CT dose is the largest contributor to the total dose, justifying a scan area limitation or low-dose protocols for whole-body scanning. An exception is the 67Ga-citrate study, where the absorbed dose to the fetus may exceed 50 mGy, with the largest contribution to the dose coming from the maternally administered radiopharmaceutical. Conclusion: The results obtained indicate that for most nuclear medicine procedures, the risks of deterministic effects in the fetus or stochastic effects in the child from the maternal diagnostic examination are minimal. It is advisable to assess doses and risks for each individual patient, taking into account the clinical situation and radiographic history.