Dosimetry in leakage of 188Re-DTPA during intracoronary balloon brachytherapy

Rhenium-188 is reported to be one of the best radionuclides for intracoronary balloon brachytherapy. Among several preparations of 188Re available for brachytherapy, 188Re-diethylene triamine penta-acetic acid (DTPA) and 188Re-mercaptoacetyltriglycine (MAG3) are recommended owing to their rapid excretion via the renal system and the absence of accumulation in the thyroid. The aim of this study was to calculate the dose of radiation exposure in a real human accident. During a 4-year clinical trial of 188Re-DTPA balloon brachytherapy in 242 patients, there was one accident involving balloon leakage. Dosimetry was performed by both image-based and biological analysis. The radiation exposure to the whole body was calculated as 113 mGy by image-based analysis and 83 or 88 mGy by biological analysis, which was approximately half the reported dose in the case of 188Re-perrhenate. The radiation exposures to other vital organs were also within the tolerated ranges. We conclude that 188Re-DTPA has better clinical feasibility and safety for intracoronary balloon brachytherapy than 188Re-perrhenate. (orig.)