Bone metastases from malignant tumors can lead to bone pain and fractures, which can seriously affect the quality of life. Strontium (Sr-89) treatment can be considered for those who meet the following conditions: 1. Bone imaging reveals multiple foci of radioactive concentration (images with many black dots); 2. Normal blood chemistry (or white blood cells > 3.0×109/L and platelets > 80×109/L) and normal liver and kidney function; 3. No chemotherapy or extensive radiotherapy within the last month; 4. The patient is in good general condition and the survival period is greater than Treatment principle: Strontium (Sr-89), after entering the body through intravenous injection, can gather at the site of bone metastases and emit β-rays to achieve the treatment purpose.