Abstract: ²²³RaCl₂ injection for bone metastasis of prostate cancer has been approved for clinical marketing and achieved good clinical effects. However, there are some defects to be solved in the actual use process. Changing the route of drug administration is an important way to regulate the metabolic distribution of drugs in vivo. In this study, ²²³RaCl₂ injection was administered by intramuscular injection in the right thigh of rats. SPECT/CT scanning was used to dynamically record the differences in targeting efficiency and metabolic clearance between intramuscular protocol and intravenous protocol. The results showed that the drug diffusion of ²²³RaCl₂ injection at the injection site was completed within 12 hours after intramuscular injection, and the proportion of bone deposition obtained by intramuscular injection was significantly higher than that of intravenous injection group, while the systemic clearance rate was faster. After the completion of the 9 days observation period, no skin burns or blood changes directly caused by ²²³RaCl₂ injection were observed, preliminarily manifesting the safety of the protocol. Therefore, under the premise of strict control of drug volume, ²²³RaCl₂ injection can improve the drug efficiency of bone deposition and avoid some side effects by intramuscular injection.