201Tl-labelled TlCl dosimetry revisited

A review of the literature pertaining to the human dosimetry of 201Tl-labelled thallous chloride provides a spectrum of organ absorbed doses associated with this radiopharmaceutical. A more recent article details human quantitative studies up to 216 h postadministration. This multiorgan radiopharmacological study, however, reports the kidney dosimetry to be significantly lower than previous values; 0.0647 mGy MBq1 (0.238 rad mCi-1) compared to 0.326 mGy MBq-1 (1.2 rad mCi-1). Because of the latter discrepancy the dosimetry was recalculated using the reported pharmacodynamic data. This recalculation resulted in a kidney radiation dose comparable to previously published reports of 0.514 mGy MBq-1 (1.89 rad mCi-1). Also, revised absorbed doses to the various segments of the gastrointestinal tract (GIT) were significantly higher.