Dosimetry and preliminary human studies of ¹⁸F-5-fluorouracil

The relative distribution, metabolism and kinetics of ¹⁸F containing compounds, following administration of ¹⁸F-5-fluorouracil, has been proposed as a prognostic aid in predicting response to 5-fluorouracil chemotherapy. Because ¹⁸F has a relatively short physical half-life (t _{1 2} = 110 min), and the distribution and kinetics of the radiolabeled 5-fluorouracil need to be studied over periods of time that range over several half-lives of the radionuclide, significant quantities of the labeled drug must be administered in order to obtain good counting statistics. The distribution of ¹⁸F, following injection of ¹⁸F-5-fluorouracil to rats and mice, has been well documented in our previous work. It appears that the distribution of ¹⁸F in humans, following administration of ¹⁸F-5-fluorouracil is similar to that in rats. We calculated the radiation dose according to the MIRD technique for the eleven main target organs for a reference man. The critical organs, according to these calculations, are the bladder wall, the kidney and the liver, receiving a radiation dose of 729, 184 and 114 mrad per mCi injected, respectively.