Salivary glands can accumulate 131 I and may demage its function during 131 I treated thyroid cancer. The purpose of this study is to understand the extent of the injury and its relation with dosage after high-dose radioiodine therapy. Radionuclide dynamic imaging is used to quantitatively calculate the absorption rate and excretion rate of salivary glands. There was no significant difference between patients group and normal controls in absorption rate ( P >0.05)

but there exieted difference in excretion rate ( P <0.05). Absorption rate and excretion rate decreased as the therapy dosage increased and significant difference existed in the >37MBq group with dosage but among the groups with dosage <37MBq. Only the excretion rate had significant difference ( P <0.05). Submandibular glands were less injuried comparing with parotid glands. Salivary glands function showed nearly normal or slightly injurled among young patients and those who received lower therapy dosage. It was concluded that quantitative radionuclide image can measure the absorption and excretion rate of salivary fland to reflect the function and injury extent. Therefore provided an evidence for clinical diagnosis. the injury extent was positively comelated to the dosage of 131 I treatment.