131I clearance is indicated for DTC metastases (including local lymph node metastases and distant metastases) that cannot be surgically removed but have iodine uptake. The aim of treatment is to remove the lesion or partially relieve the disease. The efficacy of focal clearance therapy is directly related to the extent of 131I uptake by the metastases and the retention time of 131I in the lesions, and is also influenced by the patient’s age, the size and location of the metastases, and the radiosensitivity of the lesions to 131I. Younger patients have a higher likelihood of obtaining a cure, and small metastases in soft tissues and lungs are easily cleared; metastases that have formed substantial masses or bone metastases with combined bone destruction are often poorly treated with focal clearance, even if the lesions clearly take up 131I. Advanced age, concomitant other serious diseases or those who cannot tolerate pre-treatment hypothyroidism should not be treated with 131I clearance. Metastases located at critical sites (e.g. intracranial or paraspinal, intra-airway, paragonadal metastases, etc.) are not suitable for 131I focal clearance therapy if they are inoperable, even if the lesions take up 131I significantly, and should be treated by other methods.