Assessment of fetal and maternal radiation absorbed dose in 18F-FDG PET imaging

Clinical application of PET imaging for diagnosis, staging,                    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.

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.

The obtained results indicate that the absorbed dose of 18F-FDG PET imaging the fetal is 2.50×10-2 mGy/MBq early; 2.04×10-2 mGy/MBq first three months of pregnancy, 1.80 ×10-2 mGy/MBq second three months, and 1.50 ×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.

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.