In France, 3,700 new cases of thyroid cancer are diagnosed each year. Differentiated thyroid carcinoma represents more than 90% of all thyroid cancers; and has a 10-year survival of 90-95% of patients. This favorable prognosis is the result of an effective primary therapy, which consists of a total thyroidectomy that is followed by radio-iodine ablation with 3,7GBq (100mCi) in case of significant risk of persistent disease. Few centers investigated the possibility to administer lower doses of 131I (1GBq, 30 mCi), in order to limit the potential long-term adverse complications for patients and to respond to radioprotection rules for family members and medical staff.