TG and metastatic malignant neoplasm in the lymph nodes: In our hospital, DTC patients are routinely given a dose of 100 mCi and patients with suspected or confirmed microscopic residual lesions, lymph node metastasis, distant metastasis or unexplained serum Tg level increase are given a higher dose of 131I (100–200 mCi) according to the disease extent (e.g., extent of metastasis and the elevation of Tg level) (6).