Estimated human absorbed dose of a new 153Sm bone seeking agent based on biodistribution data in mice: Comparison with 153Sm-EDTMP

Abstract

PurposeThe main goal in radiotherapy is to deliver the absorbed dose within the target organs in highest possible amount, while the absorbed dose of the other organs, especially the critical organs, should be kept as low as possible. In this work, the absorbed dose to human organs for a new 153Sm bone-seeking agent was investigated. Methods153Sm-(4-{[(bis(phosphonomethyl))carbamoyl]methyl}-7,10-bis(carboxymethyl)-1,4,7,10-tetraazacyclododec-1-yl) acetic acid (153Sm-BPAMD) complex was successfully prepared. The biodistribution of the complex was investigated in male Syrian mice up to 48 h post injection. The human absorbed dose of the complex was estimated based on the biodistribution data of the mice by radiation absorbed dose assessment resource (RADAR) method. The target to non-target absorbed dose ratios for 153Sm-BPAMD were compared with these ratios for 153Sm-EDTMP. ResultsThe highest absorbed dose for 153Sm-BPAMD was observed in bone surface with 5.828 mGy/MBq. The dose ratios of the bone surface to the red marrow and to the total body for 153Sm-BPAMD were 5.3 and 20.0, respectively, while these ratios for 153Sm-EDTMP were 4.4 and 18.3, respectively. This means, for a given dose to the bone surface as the target organ, the red marrow (as the main critical organ) and the total body would receive lesser absorbed dose in the case of 153Sm-BPAMD. ConclusionsGenerally, the human absorbed dose estimation of 153Sm-BPAMD indicated that all other tissues approximately received insignificant absorbed dose in comparison with bone surface and therefore can be regarded as a new potential agent for bone pain palliation therapy.