[F-18]fluoroestradiol radiation dosimetry in human PET studies

[F-18]16 alpha -fluoroestradiol (FES) is a PET imaging agent useful for the study of estrogen receptors in breast cancer. We estimated the radiation d osimetry for this tracer using data obtained in patient studies. Methods: T ime-dependent tissue concentrations of radioactivity were determined from b lood samples and PET images in 49 patients (52 studies) after intravenous i njection of FES. Radiation absorbed doses were calculated using the procedu res of the MIRD committee, taking into account the variation in dose based on the distribution of activities observed in the individual patients. Effe ctive dose equivalent was calculated using International Commission on Radi ological Protection Publication 60 weights for the standard woman. Results: The effective dose equivalent was 0.022 mSv/MBq (80 mrem/ mCi). The organ that received the highest dose was the liver (0.13 mGy/MBq [470 mrad/mCi]), followed by the gallbladder (0.10 mGy/MBq [380 mrad/mCi]) and the urinary bladder (0.05 mGy/MBq [190 mrad/mCi]). Conclusion: The organ doses are comp arable to those associated with other commonly performed nuclear medicine t ests. FES is a useful estrogen receptor-imaging agent, and the potential ra diation risks associated with this study are well within accepted limits.