The robotic thyroidectomy (RT) has excellent cosmetic and several functional results. But there were no definite evidence of oncological safety of robotic thyroidectomy yet. To assure the surgical completeness of robotic thyroidectomy, the investigators compared robotic thyroidectomy and conventional open thyroidectomy (OT) by means of the postoperative radioactive iodine (RAI) uptake of possible remnant thyroid tissue and stimulated TG level.

Inclusion Criteria:

• age ≥ 20years
• papillary thyroid carcinoma patients who underwent conventional open or robotic bilateral total thyroidectomy at YUHS(Yonsei University Health System)
• patient who underwent postoperative low doe (30mCI) RAI ablation therapy at YUHS

Exclusion Criteria:

• pregnant, lactating women
• patient who underwent postoperative low dose RAI at another hospital
• patient with distant metastasis
• patient who underwent combined operation with bilateral total thyroidectomy (ex) Modified radical neck dissection, selective neck node excision d/t lateral neck node metastasis
• patient who underwent High dose (more than 30 mCI) RAI therapy

papillary thyroid carcinoma patient who underwent conventional open or robotic bilateral total thyroidectomy procedure and postoperative low dose RAI therapy