Preclinical and human dosimetric aspects of [113mIn]In-BPAMD: A new agent for SPECT imaging of bone metastases.

Considering the favorable decay characteristics of 113mIn, this study aimed to prepare, perform quality control, and evaluate the human dosimetry of [113mIn] In-BPAMD. [113mIn] InCl3 was obtained from an in-house developed 113Sn/113mIn generator, and the optimal conditions for the complex preparation were determined. The radiolabeled compound was produced with a radiochemical purity (RCP) of over 99% and a specific activity of 7.9 TBq/mmol. The complex demonstrated high stability in vitro and in human serum for up to 180 min and exhibited strong in vitro binding affinity to hydroxyapatite. Biodistribution studies in male Syrian rats confirmed predominant accumulation in the bone. Based on the biodistribution data and Medical Internal Radiation Dose (MIRD) calculations, the highest absorbed dose was observed in the bone surface (0.002 mGy/MBq), while other organs received negligible doses. These findings suggest that [113mIn] In-BPAMD can be considered a safe and promising agent for SPECT imaging of bone disorders.