en Radiation Biology Radiation Biology تحقيق بديع Original Research <div style="text-align: justify;">Background: Clinical application of PET imaging for diagnosis, staging,&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; re-staging treatment planning and treatment response assessment have become a major focus of studies in the past decades. Fetus is more sensitive to ionizing radiation, consequently, radiation absorption risks need to be assessed carefully. The objective of this article is to accurately estimate the absorbed dose during pregnancy in PET examinations. The method adopted in this article is simulative-analytic. Materials and Methods: The absorbed dose from administrating 18F-FDG during pregnancy is estimated through the BodyBuilder anthropomorphic mathematical phantom (inexpensive) together with Monte Carlo simulations in order to obtain a reliable and feasible methodology. In this simulation, the Specific Absorbed Fractions (SAF) is estimated for organs of 3, 6 and 9-months fetal. Results: The obtained results indicate that the absorbed dose of 18F-FDG PET imaging the fetal is 2.50&times;10-2 mGy/MBq early; 2.04&times;10-2 mGy/MBq first three months of pregnancy, 1.80 &times;10-2 mGy/MBq second three months, and 1.50 &times;10-2 mGy/MBq in the third three months of pregnancy. Maternal absorbed dose estimation here is (R2=0.965) which perfectly corresponds to ICRP publication. Conclusion: The results from Monte Carlo code with BodyBuilder anthropomorphic phantoms and ICRP recommendation are of acceptable correlation. Applying the pure BodyBuilder anthropomorphic phantoms in this simulation, which yields agreeable results in addition to its low time consumption, corresponds to the available finding by other researchers while reducing calculation times. Moreover, the fetal & maternal absorbed doses remain however well below the threshold for any deterministic effects.</div> Fetal dose, maternal dose, GATE/GEANT4, PET/CT, 18F-FDG. 651 657 http://ijrr.com/browse.php?a_code=A-10-1-828&slc_lang=en&sid=1 N. Ahmadi 7900319475328460014035 7900319475328460014035 No Department of Nuclear Engineering, Faculty of Advanced Sciences & Technologies, University of Isfahan, Isfahan, Iran A. Karimian 7900319475328460014036 7900319475328460014036 No Department of Biomedical Engineering, University of Isfahan, Isfahan, Iran M.N. Nasrabadi mnnasrabadi@ast.ui.ac.ir 7900319475328460014037 7900319475328460014037 Yes Department of Nuclear Engineering, Faculty of Advanced Sciences & Technologies, University of Isfahan, Isfahan, Iran A. Rahmim 7900319475328460014038 7900319475328460014038 No Department of Radiology, Johns Hopkins University, Baltimore MD, USA